Identification of genetic markers for fat deposition and meat tenderness on bovine chromosome 5: development of a low-density single nucleotide polymorphism map

As genetic markers, SNP are well suited for the development of genetic tests for production traits in livestock. They are stable through many generations and can provide direct assessment of individual animal's genetic merit if they are in linkage disequilibrium and phase with functional genetic variation. Bovine chromosome 5 has been shown to harbor genetic variation affecting production traits in multiple cattle populations; thus, this chromosome was targeted for SNP-based marker development and subsequent association analysis with carcass and growth phenotypes. Discovery of SNP was performed in a panel of 16 sires representing two sires from each of seven beef breeds and two Holstein sires by PCR amplification and sequencing using primers designed from genomic sequence obtained by low-coverage sequencing of bacterial artificial chromosome (BAC) clones. From 550 SNP, 296 (54%) were tentatively identified as having a minor allele frequency >10%. Forty-five SNP derived from 15 BAC were chosen based on minor allele frequency and were genotyped in 564 steers and their sires. Production and carcass data were collected on the steers as a part of the Germplasm Evaluation (GPE), Cycle VII Project at the U.S. Meat Animal Research Center (Clay Center, NE), which involves of the evaluation of sires from seven of the most popular U.S. breeds. Haplotypes based on seven SNP derived from a BAC containing the bovine genes HEM1 and PDE1B were associated with traits related to carcass fat. Steers homozygous for the major haplotype had 0.15 +/- 0.04 cm less subcutaneous fat, 0.57 +/- 0.18 kg less rib fat, 0.18 +/- 0.07 lower yield grade, 1.11 +/- 0.35% less predicted fat yield, and 0.79 +/- 0.3% greater predicted retail product yield than heterozygotes. The frequency of the major haplotype was 0.70 in the steers, and it ranged from 0.44 (Limousin) to 0.98 (Simmental and Gelbvieh) in a panel consisting of an average of 20 purebred sires from each of the seven breeds. A second set of haplotypes based on four SNP derived from a BAC containing the genes NOL1 and CHD4 was associated with Warner-Bratzler shear force. Steers homozygous for the major haplotype had 0.27 +/- 0.11 kg greater shear force than those heterozygous for the major haplotype and one of two minor haplotypes. The frequency of the major haplotype was 0.59 in the steers and ranged from 0.27 (Hereford) to approximately 0.95 (Angus and Red Angus) in the panel of purebred sires. These results demonstrate the feasibility of targeting QTL regions for SNP-based marker development and that a low level of coverage can identify markers associated with phenotypic traits.

A new single nucleotide polymorphism in CAPN1 extends the current tenderness marker test to include cattle of Bos indicus, Bos taurus, and crossbred descent

The three objectives of this study were to 1) test for the existence of beef tenderness markers in the CAPN1 gene segregating in Brahman cattle; 2) test existing CAPN1 tenderness markers in indicus-influenced crossbred cattle; and 3) produce a revised marker system for use in cattle of all subspecies backgrounds. Previously, two SNP in the CAPN1 gene have been described that could be used to guide selection in Bos taurus cattle (designated Markers 316 and 530), but neither marker segregates at high frequency in Brahman cattle. In this study, we examined three additional SNP in CAPN1 to determine whether variation in this gene could be associated with tenderness in a large, multisire American Brahman population. One marker (termed 4751) was associated with shear force on postmortem d 7 (P < 0.01), 14 (P = 0.015), and 21 (P < 0.001) in this population, demonstrating that genetic variation important for tenderness segregates in Bos indicus cattle at or near CAPN1. Marker 4751 also was associated with shear force (P < 0.01) in the same large, multisire population of cattle of strictly Bos taurus descent that was used to develop the previously reported SNP (referred to as the Germplasm Evaluation [GPE] Cycle 7 population), indicating the possibility that one marker could have wide applicability in cattle of all subspecies backgrounds. To test this hypothesis, Marker 4751 was tested in a third large, multisire cattle population of crossbred subspecies descent (including sire breeds of Brangus, Beefmaster, Bonsmara, Romosinuano, Hereford, and Angus referred to as the GPE Cycle 8 population). The highly significant association of Marker 4751 with shear force in this population (P < 0.001) confirms the usefulness of Marker 4751 in cattle of all subspecies backgrounds, including Bos taurus, Bos indicus, and crossbred descent. This wide applicability adds substantial value over previously released Markers 316 and 530. However, Marker 316, which had previously been shown to be associated with tenderness in the GPE Cycle 7 population, also was highly associated with shear force in the GPE Cycle 8 animals (P < 0.001). Thus, Marker 316 may continue to be useful in a variety of populations with a high percentage of Bos taurus backgrounds. An optimal marker strategy for CAPN1 in many cases will be to use both Markers 316 and 4751.

Growth and pubertal development of F1 bulls from Hereford, Angus, Norwegian Red, Swedish Red and White, Friesian, and Wagyu sires1,2

The objective of the study was to characterize body growth, testicular development, and puberty from 8 to 14 mo of age in bulls (n = 120) produced by mating sires from Hereford, Angus, Norwegian Red, Swedish Red and White, Friesian, and Wagyu breeds to MARC III ((1/4) Hereford, (1/4) Angus, (1/4) Red Poll, and (1/4) Pinzgauer) cows. Traits evaluated were birth weight, weaning weight (at 215 d), yearling weight, ADG from 8 to 14 mo of age, paired testicular volume growth from 8 to 14 mo of age, age at puberty (determined by production of 50 x 10(6) sperm with 10% motility), age at freezable semen (determined by production of 500 x 10(6) sperm with 50% motility), and, at 15 mo of age, paired testicular weight and daily sperm production per testis pair. There was an effect of sire breed (P = 0.03) for age at puberty; animals with Wagyu and Swedish Red and White inheritance reached puberty at a later date (302 and 302 d of age, respectively) compared with Angus-sired bulls (268 d). Age at puberty for Hereford-, Norwegian Red-, and Friesian-sired bulls was 270, 271, and 278 d, respectively. Differences in BW were observed (P = 0.03) at birth; bulls with Hereford and Friesian were heavier at birth (43 and 41 kg, respectively) compared with those with Norwegian Red, Swedish Red and White, and Wagyu inheritance (39, 38, and 38 kg, respectively). Differences in BW were also observed at 1 yr of age (P = 0.001), where the heaviest animals were those sired by Angus (450 kg), whereas the lightest animals were those sired by Wagyu (403 kg). Bulls with Wagyu inheritance had the lowest (P = 0.04) ADG (1.12 kg/d) compared with bulls with inheritance from Hereford (1.22 kg/d), Angus (1.28 kg/d), Norwegian Red (1.24 kg/d), Swedish Red and White (1.25 kg/d), and Friesian (1.27 kg/d). Differences in scrotal growth rate were not significant (P = 0.99). They ranged from 1.95 in Angus-sired to 1.66 cm3/d in Wagyu-sired bulls. There were no differences (P = 0.80) for age at freezable semen (335 +/- 10 d). At slaughter (15 mo of age), there were no differences (P = 0.62) for paired testicular weight (603 +/- 28 g) and daily sperm production (10.6 x 10(9) +/- 0.9 x 10(9) per testis pair). Growth of bulls with Wagyu inheritance was slower, and bulls with Wagyu or Scandinavian inheritance reach puberty at an older age than bulls with Angus inheritance.

Assessing the association of single nucleotide polymorphisms at the thyroglobulin gene with carcass traits in beef cattle

The objective of this study was to assess the association of SNP in the thyroglobulin gene, including a previously reported marker in current industry use, with marbling score in beef cattle. Three populations, designated GPE6, GPE7, and GPE8, were studied. The GPE6 population sampled breeds that could be used as alternative germplasm sources in beef cattle production, including Wagyu, Swedish Red and White, Friesian, and Norwegian Red. The GPE7 population sampled 7 popular beef cattle breeds used in temperate climates of the United States: Angus, Charolais, Gelbvieh, Hereford, Limousin, Red Angus, and Simmental. The GPE8 population sampled Bos indicus-influenced breeds used in subtropical regions of the country and subtropical and tropical regions of the world, including Beefmaster, Bonsmara, Brangus, and Romosinuano. Evaluation of 6 SNP in the thyroglobulin gene, including 5 newly described variations, showed no association (P > 0.10) with marbling score in these populations, except a tendency (P < 0.10) for an association with the previously described marker in GPE6. Closer examination of the GPE6 data revealed that the source of the tendency was an association (P < 0.02) with marbling in animals of Wagyu inheritance. Animals having Wagyu background and inheriting the TT genotype had a greater marbling score (599 +/- 20) than those inheriting the CC (540 +/- 10) or the CT (541 +/- 11) genotype. No association was detected with any other carcass trait for this marker in the 3 populations. Furthermore, none of the 5 newly described markers in the gene displayed an association with marbling score. The data indicate that markers at the thyroglobulin gene may be a useful predictor of marbling performance for producers raising Wagyu-based cattle. Although associations with marbling score in the remaining populations were not large or significant, the TT genotype had the numerically greatest marbling score in each population.

Predicting gene promoter methylation in non-small-cell lung cancer by evaluating sputum and serum

The use of 5-methylcytosine demethylating agents in conjunction with inhibitors of histone deacetylation may offer a new therapeutic strategy for lung cancer. Monitoring the efficacy of gene demethylating treatment directly within the tumour may be difficult due to tumour location. This study determined the positive and negative predictive values of sputum and serum for detecting gene methylation in primary lung cancer. A panel of eight genes was evaluated by comparing methylation detected in the primary tumour biopsy to serum and sputum obtained from 72 patients with Stage III lung cancer. The prevalence for methylation of the eight genes in sputum (21–43%) approximated to that seen in tumours, but was 0.7–4.3-fold greater than detected in serum. Sputum was superior to serum in classifying the methylation status of genes in the tumour biopsy. The positive predictive value of the top four genes (p16, DAPK, PAX5 β, and GATA5) was 44–72% with a negative predictive value for these genes ⩾70%. The highest specificity was seen for the p16 gene, and this was associated with a odds ratio of six for methylation in the tumour when this gene was methylated in sputum. In contrast, for serum, the individual sensitivity for all genes was 6–27%. Evaluating the combined effect of methylation of at least one of the four most significant genes in sputum increased the positive predictive value to 86%. These studies demonstrate that sputum can be used effectively as a surrogate for tumour tissue to predict the methylation status of advanced lung cancer where biopsy is not feasible.

Evaluation in beef cattle of six deoxyribonucleic acid markers developed for dairy traits reveals an osteopontin polymorphism associated with postweaning growth

The objectives of this study were to 1) estimate the allelic frequencies in US beef cattle of 6 DNA markers reported to be associated with variation in dairy production traits; and 2) evaluate the association of these markers with beef production traits. Several genetic markers have been associated with milk yield or composition, including polymorphisms in secreted phosphoprotein 1 (SPP1; also called osteopontin), growth hormone receptor (GHR), casein S1 (CSN1S1), diacylglycerol O-acyltransferase 1 (DGAT1), peroxisome proliferator-activated receptor gamma co-activator-1alpha (PPARGC1A), and ATP-binding cassette subfamily G (white) member 2 (ABCG2). Allelic frequencies for these 6 markers, and their association with 21 phenotypes, were evaluated in 2 crossbred beef cattle populations that sample influential industry sires. Five of 6 markers were segregating in beef cattle populations; the exception was ABCG2. The SPP1 marker was associated with yearling weight (P = 0.025), live weight at slaughter (P = 0.016), postweaning ADG (P = 0.007), and HCW (P = 0.007) in a large, multisire population representing the 7 most populous beef breeds in the United States. Postweaning growth trait associations were confirmed in an independent population of similar construction, including sires from tropically adapted breeds. The SPP1 marker was associated with yearling weight (P = 0.034), live weight at slaughter (P = 0.011), and postweaning ADG (P = 0.015) and showed a trend toward association with HCW (P = 0.083) in this population. Whereas DGAT1, GHR, and CSN1S1 polymorphisms showed association with some traits in individual populations, the lack of consistent predictive merit between populations indicates they may not be suited for beef cattle selection. No significant associations were observed for the PPARGC1A marker and any of 21 recorded traits, indicating this marker had no apparent value in selection for the beef cattle traits tested in these populations. The SPP1 marker had consistent associations and effect sizes (10.5 to 11.5 kg of live weight at slaughter) in both populations, providing strong evidence for utility of the SPP1 marker for postweaning growth in beef cattle.

Putative quantitative trait loci associated with the probability of contracting infectious bovine keratoconjunctivitis1,2

Infectious bovine keratoconjunctivitis, also known as pinkeye, is an economically important disease in cattle. The objective of this study was to detect QTL associated with infectious bovine keratoconjunctivitis in offspring from a Brahman x Hereford sire. The sire was mated to Hereford, Angus, and F1 cows to produce 288 offspring in 1994 and mated to MARC III ((1/4) Hereford, (1/4) Angus, (1/4) Red Poll, and (1/4) Pinzgauer) cows in 1996 to produce 259 offspring (547 animals total). Infectious bovine keratoconjunctivitis was diagnosed by physical examination in 36 animals of the family. Records included unilateral and bilateral frequency, but not severity. Records were binary: 0 for unaffected and 1 for affected cattle. A putative QTL for infectious bovine keratoconjunctivitis was identified on chromosome 1, with a maximum F-statistic (F = 10.15; P = 0.0015) at centimorgan 79 of the linkage group. The support interval spanned centimorgans 66 to 110. There was also evidence suggesting the presence of a QTL for infectious bovine keratoconjunctivitis on chromosome 20, with a maximum F-statistic (F = 10.35; P = 0.0014) at centimorgan 16 of the linkage group. The support interval ranged from centimorgan 2 to 35. This report provides the initial evidence of QTL for infectious bovine keratoconjunctivitis. Although a candidate gene was identified for one of the regions of interest, further studies are needed to identify the genetic basis of resistance to the disease.

Association of markers in the bovine CAPN1 gene with meat tenderness in large crossbred populations that sample influential industry sires

Two previously identified single-nucleotide polymorphism markers located within the micromolar calcium-activated neutral protease gene (CAPN1) were evaluated for their association with variation in meat tenderness using one commercial sample of Simmental x Angus crossbred calves and one multibreed, crossbred research herd. The commercial sample included 362 animals sired by 23 registered Simmental bulls bred to unregistered Angus cows and represented current industry animals in which to test the predictive merit of the markers. The second sample was a research herd including 564 steers from the Germplasm Evaluation Cycle VII population at the U.S. Meat Animal Research Center, produced with semen from popular sires of the seven Bos taurus beef breeds with the most registrations in the United States (Angus, Charolais, Gelbvieh, Hereford, Limousin, Red Angus, and Simmental) on Angus, Hereford, and MARC III cows. These animals form a relatively outbred population that constituted a stringent test of the predictive merit of the genetic markers, although small groups were half-sibs. Warner-Bratzler shear force measurements were used to determine tenderness phenotypes for all animals. The populations were genotyped for two markers that predict variation at amino acid positions 316 and 530 of the mu-calpain polypeptide, produced by the CAPN1 gene. Minor allele frequencies for markers 316 and 530 in the commercial sample were 0.17 and 0.37, respectively, and in the Cycle VII animals, were 0.20 and 0.28, respectively. Both markers showed association with shear force in the commercial sample (P = 0.04) and the Cycle VII population (P = 0.02), supporting the hypothesis that they represent potential markers to aid selection for improved meat tenderness in commercial populations of beef cattle in the United States.

Association of a single nucleotide polymorphism in SPP1 with growth traits and twinning in a cattle population selected for twinning rate

Continued validation of genetic markers for economically important traits is crucial to establishing marker-assisted selection as a tool in the cattle industry. The objective of the current study was to evaluate the association of a SNP (T(9)/T(10)) in the osteopontin gene (SPP1) with growth rate in a large cattle population spanning multiple generations and representing alleles from 12 founding breeds. This population has been maintained at the US Meat Animal Research Center since 1981 and subjected to selection for twinning rate. Phenotypic records for this population included twinning rate and ovulation rate, providing an opportunity to examine the potential effects of SPP1 genotype on reproductive traits. A set of 2,701 animals was geno-typed for the T(9)/T(10) polymorphism at SPP1. The geno-typic data, including previously genotyped markers on chromosome 6 (BTA6), were used in conjunction with pedigree information to estimate genotypic probabilities for all 14,714 animals with phenotypic records. The genotypic probabilities for females were used to calculate independent variables for regressions of additive, dominance, and imprinting effects. Genotypic regressions were fit as fixed effects in a mixed model analysis, in which each trait was analyzed in a 2-trait model where single births were treated as a separate trait from twin births. The association of the SPP1 marker with birth weight (P < 0.006), weaning weight (P < 0.007), and yearling weight (P < 0.003) was consistent with the previously reported effects of SPP1 genotype on yearling weight. Our data supports the conclusion that the SNP successfully tracks functional alleles affecting growth in cattle. The previously undetected effect of the SNP on birth and weaning weight suggests this particular SPP1 marker may explain a portion of the phenotypic variance explained by QTL for birth and HCW on BTA6.

Effects of calpastatin and μ-calpain markers in beef cattle on tenderness traits1,2

The objective of this study was to assess the association of single nucleotide polymorphisms (SNP) developed at the calpastatin (CAST) and mu-calpain (CAPN1) genes with meat tenderness and palatability traits in populations with diverse genetic backgrounds. Three populations were used in the study. One population consisted of Bos taurus that included crossbred animals derived from Hereford, Angus, Red Angus, Limousin, Charolais, Gelbvieh, and Simmental (GPE7; n = 539). Another population consisted of Bos taurus with Bos indicus influence, including crossbred animals from Hereford, Angus, Brangus, Beefmaster, Bonsmara, and Romosinuano (GPE8; n = 580). The third population was Bos indicus and consisted of purebred Brahman (STARS; n = 444). Traits evaluated were meat tenderness measured as Warner-Bratzler shear force (WBSF; kg) at 14 d postmortem, and traits evaluated by trained sensory panels that included tenderness score, juiciness, and flavor intensity. A SNP at the CAST gene had a significant (P < 0.003) effect on WBSF and tenderness score in the GPE7 and GPE8 populations. Animals inheriting the TT genotype at CAST had meat that was more tender than those inheriting the CC genotype. The marker at the CAPN1 gene was significant (P < 0.03) for tenderness score in GPE7 and GPE8. Animals inheriting the CC genotype at CAPN1 had meat that was more tender than those inheriting the TT genotype. Markers at the CAST and CAPN1 genes were associated with flavor intensity in the GPE8 population. Animals inheriting the CC genotype at CAST and the TT genotype at CAPN1 produced steaks with an intense flavor when compared with the other genotypes. An interaction between CAST and CAPN1 was detected (P < 0.05) for WBSF on GPE8. The statistical significance of the interaction is questionable because of the limited number of observations in some cells. Markers developed at the CAST and CAPN1 genes are suitable for use in identifying animals with the genetic potential to produce meat that is more tender.

Postweaning growth and carcass traits in crossbred cattle from Hereford, Angus, Norwegian Red, Swedish Red and White, Friesian, and Wagyu maternal grandsires1,2

The objective of this study was to characterize breeds representing diverse biological types for postweaning growth and carcass composition traits in terminal crossbred cattle. Postweaning growth and carcass traits were analyzed on 434 steers and 373 heifers obtained by mating F1 cows to Charolais sires. Maternal grandsires represented Hereford, Angus, and MARC III (1/4 Hereford, 1/4 Angus, 1/4 Pinzgauer, and 1/4 Red Poll) dams to Hereford or Angus (British Breeds), Norwegian Red, Swedish Red and White, Wagyu, or Friesian breeds. Breed groups were slaughtered serially in each of 2 yr (2002 and 2003). Postweaning ADG, slaughter weight, hot carcass weight, dressing percentage, percentage Choice, LM area, marbling score, USDA yield grade, fat thickness, retail product yield (percentage), retail product weight, fat yield (percentage), fat weight, bone yield (percentage), and bone weight were analyzed. Maternal grandsire breed was significant (P < 0.05) for all traits except dressing percentage, percentage Choice, and LM area. Marbling score for animals with Norwegian Red, Wagyu, Swedish Red and White, British Breeds, and Friesian inheritance was 550, 544, 532, 530, and 515, respectively (SEM = 8). Retail product weight for these animals was 224, 211, 227, 223, and 223 kg, respectively (SEM = 2 kg). Maternal granddam breed was not significant for any of the traits analyzed. Grandsire breed effects can be optimized by selection and use of appropriate crossbreeding systems.

Evaluation of Dorset, Finnsheep, Romanov, Texel, and Montadale breeds of sheep: V. Reproduction of F1 ewes in spring mating seasons1,2

Objectives were to estimate effects of sire breed (Dorset, Finnsheep, Romanov, Texel, and Montadale), dam breed [Composite III (CIII) and northwestern whiteface (WF)], mating season (March and May), and their interactions on reproductive traits of mature F1 ewes in spring mating seasons. A total of 1,099 F1 ewes produced 1,754 litters of 2,995 lambs from exposures to Suffolk rams during March and May mating seasons in 1995 through 1999. Fertility rate and ewe longevity were measured. Number born and litter birth weight were recorded, and number and weight at weaning and 20 wk of age were analyzed separately for dam- and nursery-reared litter mates. Total productivity from 4 to 6 yr of age for each ewe entering the breeding flock was calculated as the sum of 20-wk weights for dam-reared lambs and separately for nursery-reared lambs. Interactions of sire breed x mating season, ewe age x mating season, and ewe age x dam breed were often significant. Interactive effects of sire breed and mating season on fertility rate (P < 0.001) were primarily due to differences in magnitude. Fertility rates of sire breeds for March and May matings, respectively, were 92 and 89% for Romanov, 91 and 72% for Finnsheep, 90 and 52% for Texel, 88 and 52% for Montadale, and 83 and 62% for Dorset. Sire breed x mating season also affected number born (P < 0.03); March and May values were 2.12 and 2.05 for Romanov, 2.00 and 1.94 for Finnsheep, 1.39 and 1.41 for Texel, 1.37 and 1.51 for Montadale, and 1.37 and 1.55 for Dorset, respectively. Interaction of sire breed x dam breed on fertility rate (P < 0.01) was due to change in rank as well as magnitude. Romanov- and Dorset-sired ewes out of CIII dams had greater fertility rates than Romanov- and Dorset-sired ewes out of WF dams. The opposite situation existed for ewes by Finnsheep, Texel, and Montadale sires. Differences between dam breeds (CIII and WF) in total productivity of dam-reared lambs were not detected, whereas ewes exposed in March (78 kg) were more productive (P < 0.01) than those exposed in May (68 kg). Means of sire breeds for total productivity of dam-reared lambs were 47, 65, 70, 70, and 111 kg for Texel, Montadale, Dorset, Finnsheep, and Romanov, respectively (P < 0.001). Superior reproduction of Romanov sired ewes was primarily due to greater fertility rate and prolificacy at each mating season and ewe age. Use of Romanov-crossbred ewes would increase fertility during spring mating, an important constraint of the sheep industry.

Inhibition of sperm-zona pellucida binding by a 55 kDa pig sperm protein in vitro

This study was conducted to evaluate the role of a 55 kDa pig sperm protein on the oocytesperm binding process, and its location in situ. For this purpose, in vitro matured oocytes were incubated with isolated and purified protein, and incubated with capacitated spermatozoa. In addition, capacitated sperm were incubated with anti-55 kDa antiserum and later with mature oocytes. Immunolocalization assays were performed using non-capacitated, capacitated and acrosome reacted sperm, which were incubated independently with anti-55 kDa protein antibodies and analyzed under fluorescence light microscopy. The 55 kDa protein concentrations correlated negatively with the amounts of sperm bound to the zona pellucida (ZP); the presence of the anti-55 kDa protein totally inhibited this binding. The immunolocalization assays revealed that fluorescence was located preferentially at the apical edge of the head in capacitated sperm, but not in acrosome reacted sperm. It would appear that the 55 kDa protein binds specifically to the oocyte ZP, and that it may be responsible for primary gamete binding during fertilization.

Evaluation of Dorset, Finnsheep, Romanov, Texel, and Montadale breeds of sheep: II. Reproduction of F1 ewes in fall mating seasons

Objectives were to estimate effects of sire breed (Dorset, Finnsheep, Romanov, Texel, and Montadale), dam breed (Composite III and northwestern whiteface), mating season (August, October, and December), ewe age (1, 2, and 3 yr), and their interactions on reproductive traits of F1 ewes. A total of 1,799 F1 ewes produced 3,849 litters from 4,804 exposures to Suffolk rams during 35-d mating seasons over 3 yr. Ewes were weighed at breeding. Conception rate and ewe longevity (present or absent at 42 mo of age) were determined. Number born and litter birth weight were recorded, and number and weight at weaning and 20 wk of age were analyzed separately for dam- and nursery-reared litter mates. Total productivity through 3 yr of age for each ewe entering the breeding flock was calculated as the sum of 20-wk weights for dam- or nursery-reared lambs. Interactions of sire breed x mating season, sire breed x ewe age, and mating season x ewe age were generally significant, whereas interactions of sire breed, mating season, and ewe age x dam breed were seldom detected. Interactions of sire breed x mating season were often due to changes in rank as well as magnitude, indicating the importance of matching sire breed to a specific mating season. The number born to Dorset-, Texel-, and Montadale-sired ewes was not affected by dam breed; however, Finnsheep-sired ewes out of northwestern whiteface dams were more prolific than Finnsheep-sired ewes out of Composite III dams, and the opposite situation existed for Romanov-sired ewes. Least squares means of sire breeds (P < 0.001) for total productivity of dam-reared lambs were 98.5, 103.5, 106.9, 124.6, and 154.9 kg/ewe entering the breeding flock for Texel, Dorset, Montadale, Finnsheep, and Romanov, respectively. Superior reproduction of Romanov-sired ewes was due to greater conception rate and prolificacy for each mating season and ewe age, as well as greater ewe longevity. Total productivity of F1 ewes by Composite III dams (125.6 kg) was greater (P < 0.001) than for ewes born to northwestern whiteface dams (109.7 kg), and the effect of mating season increased (P < 0.001) from August to October to December. Litter weight at 20 wk of age of 2- and 3-yr-old ewes was similar but greater (P < 0.001) than for 1-yr-old ewes. Experimental results provide comprehensive information about the appropriate use of these breeds in crossbreeding systems to meet specific production-marketing objectives.

Quantitative trait loci for male reproductive traits in beef cattle

The objective of the present study was to detect quantitative trait loci (QTL) for male reproductive traits in a half-sib family from a Bos indicus (Brahman) x Bos taurus (Hereford) sire. The sire was mated with MARC III (1/4 Hereford, 1/4 Angus, 1/4 Red Poll and 1/4 Pinzgauer) cows. Testicular traits were measured from 126 male offspring born in 1996 and castrated at 8.5 months. Traits analysed were concentration of follicle stimulating hormone in peripheral blood at castration (FSH), paired testicular weight (PTW) and paired testicular volume (PTV) adjusted for age of dam, calculated age at puberty (AGE), and body weight at castration (BYW). A putative QTL was observed for FSH on chromosome 5. The maximum F-statistic was detected at 70 cM from the beginning of the linkage group. Animals inheriting the Hereford allele had a 2.47-ng/ml higher concentration of FSH than those inheriting the Brahman allele. Evidence also suggests the existence of a putative QTL on chromosome 29 for PTW, PTV, AGE and BYW. The maximum F-statistic was detected at cM 44 from the beginning of the linkage group for PTW, PTV and AGE, and at cM 52 for BYW. Animals that inherited the Brahman allele at this chromosomal region had a 45-g heavier PTW, a 42-cm(3) greater PTV, a 39-day younger AGE and a 22.8-kg heavier BYW, compared with those inheriting the Hereford allele. This is the first report of QTL for male reproductive traits in cattle.

Association of myostatin on early calf mortality, growth, and carcass composition traits in crossbred cattle1,2

The objective of this study was to investigate a potential association of an inactive myostatin allele with early calf mortality, and evaluate its effect on growth and carcass traits in a crossbred population. Animals were obtained by mating F1 cows to F1 (Belgian Blue x British Breed) or Charolais sires. Cows were obtained from mating Hereford, Angus, and MARC III (1/4 Hereford, 1/4 Angus, 1/4 Pinzgauer, and 1/4 Red Poll) dams to Hereford, Angus, Tuli, Boran, Brahman, or Belgian Blue sires. Belgian Blue was the source of the inactive myostatin allele. Myostatin genotypes were determined for all animals including those that died before weaning. Early calf mortality was examined in the F2 subpopulation (n = 154), derived from the F1 sires mated to F1 cows from Belgian Blue sires, to evaluate animals with zero, one, or two copies of inactive myostatin allele. An overall 1:2:1 ratio (homozygous active myostatin allele:heterozygous:homozygous inactive myostatin allele) was observed in the population; however, a comparison between calves dying before weaning and those alive at slaughter showed an unequal distribution across genotypes (P < 0.01). Calves with two copies of the inactive allele were more likely (P < 0.01) to die before weaning. Postweaning growth traits were evaluated in the surviving animals (n = 1,370), including birth, weaning, and live weight at slaughter, and postweaning ADG. Carcass composition traits analyzed were hot carcass weight, fat thickness, LM area, marbling score, USDA yield grade, estimated kidney, pelvic, and heart fat, retail product yield and weight, fat yield and weight, bone yield and weight, and percentage of carcasses classified as Choice. Charolais lack the inactive myostatin allele segregating in Belgian Blue; thus, in the population sired by Charolais (n = 645), only animals with zero or one copy of the inactive myostatin allele were evaluated. Animals carrying one copy were heavier at birth and at weaning, and their carcasses were leaner and more muscled. In the population sired by Belgian Blue x British Breed (n = 725), animals with two copies of inactive myostatin allele were heavier at birth, leaner, and had a higher proportion of muscle mass than animals with zero or one copies. Heterozygous animals were heaviest at weaning and had the highest live weight, whereas animals with zero copies had the highest fat content. The use of the inactive myostatin allele is an option to increase retail product yield, but considerations of conditions at calving are important to prevent mortality.

Pentadiene production from potassium sorbate by osmotolerant yeasts

Some yeast strains belonging to the species Zygosaccharomyces rouxii and Debaryomyces hansenii are capable of spoiling sorbate containing high-sugar foods by producing pentadiene, a volatile compound reported to have 'petroleum-like' odour. Quantification of the diminution of sorbate and the subsequent increase of pentadiene was performed by growing the yeasts in experimental media containing 600 g/l sucrose and different sorbate concentrations. Final sorbate concentrations were notably lower than their corresponding initial ones, and it was found that the higher the initial concentration of sorbate in the media, the higher the amount of pentadiene produced. In all cases, Z. rouxii was able to produce more pentadiene than D. hansenii when expressing pentadiene concentration as a function of cell biomass. These results suggest that pentadiene is a metabolite of sorbate.

Detection of quantitative trait loci for growth and carcass composition in cattle

The objective of the present study was to detect quantitative trait loci for economically important traits in a family from a Bos indicus x Bos taurus sire. A Brahman x Hereford sire was used to develop a half-sib family (n = 547). The sire was mated to Bos taurus cows. Traits analyzed were birth (kg) and weaning weights (kg); hot carcass weight (kg); marbling score; longissimus area (cm2); USDA yield grade; estimated kidney, pelvic, and heart fat (%); fat thickness (cm); fat yield (%); and retail product yield (%). Meat tenderness was measured as Warner-Bratzler shear force (kg) at 3 and 14 d postmortem. Two hundred and thirty-eight markers were genotyped in 185 offspring. One hundred and thirty markers were used to genotype the remaining 362 offspring. A total of 312 markers were used in the final analysis. Seventy-four markers were common to both groups. Significant QTL (expected number of false-positives < 0.05) were observed for birth weight and longissimus area on chromosome 5, for longissimus area on chromosome 6, for retail product yield on chromosome 9, for birth weight on chromosome 21, and for marbling score on chromosome 23. Evidence suggesting (expected number of false-positives < 1) the presence of QTL was detected for several traits. Putative QTL for birth weight were detected on chromosomes 1, 2, and 3, and for weaning weight on chromosome 29. For hot carcass weight, QTL were detected on chromosomes 10, 18, and 29. Four QTL for yield grade were identified on chromosomes 2, 11, 14, and 19. Three QTL for fat thickness were detected on chromosomes 2, 3, 7, and 14. For marbling score, QTL were identified on chromosomes 3, 10, 14, and 27. Four QTL were identified for retail product yield on chromosomes 12, 18, 19, and 29. A QTL for estimated kidney, pelvic, and heart fat was detected on chromosome 15, and a QTL for meat tenderness measured as Warner-Bratzler shear force at 3 d postmortem was identified on chromosome 20. Two QTL were detected for meat tenderness measured as Warner-Bratzler shear force at 14 d postmortem on chromosomes 20 and 29. These results present a complete scan in all available progeny in this family. Regions underlying QTL need to be assessed in other populations.

Identification of quantitative trait loci for growth and carcass composition in cattle

A genomic screening to detect quantitative trait loci (QTL) affecting growth, carcass composition and meat quality traits was pursued. Two hundred nineteen microsatellite markers were genotyped on 176 of 620 (28%) progeny from a Brahman x Angus sire mated to mostly MARC III dams. Selective genotyping, based on retail product yield (%) and fat yield (%), was used to select individuals to be genotyped. Traits included in the study were birth weight (kg), hot carcass weight (kg), retail product yield, fat yield, marbling score (400 = slight00 and 500 = small00), USDA yield grade, and estimated kidney, heart and pelvic fat (%). The QTL were classified as significant when the expected number of false positives (ENFP) was less than 0.05 (F-statistic greater than 17.3), and suggestive when the ENFP was <1 (F-statistic between 10.2 and 17.3). A significant QTL (F = 19; ENFP = 0.02) was detected for marbling score at centimorgan (cM) 54 on chromosome 2. Suggestive QTL were detected for fat yield at 50 cM, for retail product yield at 53 cM, and for USDA yield grade at 63 cM on chromosome 1, for marbling score at 56 cM, for retail product yield at 70 cM, and for estimated kidney, heart and pelvic fat at 79 cM on chromosome 3, for marbling score at 44 cM, for hot carcass weight at 49 cM, and for estimated kidney, heart and pelvic fat at 62 cM on chromosome 16, and for fat yield at 35 cM on chromosome 17. Two suggestive QTL for birth weight were identified, one at 12 cM on chromosome 20 and the other at 56 cM on chromosome 21. An additional suggestive QTL was detected for retail product yield, for fat yield, and for USDA yield grade at 26 cM on chromosome 26. Results presented here represent the initial search for quantitative trait loci in this family. Validation of detected QTL in other populations will be necessary.

Maternal grandsire, granddam, and sire breed effects on growth and carcass traits of crossbred cattle

Postweaning growth, feed efficiency, and carcass traits were analyzed on 1,422 animals obtained by mating F1 cows to F1 (Belgian Blue x British breeds) or Charolais sires. Cows were obtained from mating Hereford, Angus, and MARC IIIHereford, 1/4 Angus, 1/4 Pinzgauer, and 1/4 Red Poll) dams to Hereford or Angus (British breeds), Tuli, Boran, Brahman, or Belgian Blue sires. Breed groups were fed in replicated pens and slaughtered serially in each of 2 yr. Postweaning average daily gain; live weight; hot carcass weight; fat depth; longissimus area; estimated kidney, pelvic, and heart fat (percentage); percentage Choice; marbling score; USDA yield grade; retail product yield (percentage); retail product weight; fat yield (percentage); fat weight; bone yield (percentage); and bone weight were analyzed in this population. Quadratic regressions of pen mean weight on days fed and of cumulative ME consumption on days fed were used to estimate gain, ME consumption and efficiency (Mcal of ME/kg of gain) over time (0 to 200 d on feed), and weight (300 to 550 kg) intervals. Maternal grandsire breed was significant (P < 0.01) for all traits. Maternal granddam breed (Hereford, Angus, or MARC III)was significant (P < 0.05) only for fat depth, USDA yield grade, retail product yield, fat yield, fat weight, and bone yield. Sire breed was significant (P < 0.05) for live weight, hot carcass weight, longissimus area, and bone weight. Sex class was a significant (P < 0.001) source of variation for all traits except for percentage Choice, marbling score, retail product yield, and fat yield. Interactions between maternal grandsire and sire breed were nonexistent. Sire and grandsire breed effects can be optimized by selection and use of appropriate crossbreeding systems.

Evaluation of single-nucleotide polymorphisms in CAPN1 for association with meat tenderness in cattle

Micromolar calcium activated neutral protease (CAPN1) was evaluated as a candidate gene for a quantitative trait locus (QTL) on BTA29 affecting meat tenderness by characterization of nucleotide sequence variation in the gene. Single-nucleotide polymorphisms (SNP) were identified by sequencing all 22 exons and 19 of the 21 introns in two sires (Piedmontese x Angus located at the U.S. Meat Animal Research Center in Clay Center, NE; Jersey x Limousin located at AgResearch in New Zealand) of independent resource populations previously shown to be segregating meat tenderness QTL on BTA29. The majority of the 38 SNP were found in introns or were synonymous substitutions in the coding regions, with two exceptions. Exons 14 and 9 contained SNP that were predicted to alter the protein sequence by the substitution of isoleucine for valine in Domain III of the protein, and alanine for glycine in Domain II of the protein. The resource populations were genotyped for these two SNP in addition to six intronic polymorphisms and two silent substitutions. Analysis of genotypes and shear force values in both populations revealed a difference between paternal CAPN1 alleles in which the allele encoding isoleucine at position 530 and glycine at position 316 associated with decreased meat tenderness (increased shear force values) relative to the allele encoding valine at position 530 and alanine at position 316 (P < 0.05). The association of maternal alleles with meat tenderness phenotypes is consistent with the hypothesis of CAPN1 as the gene underlying the QTL effect in two independent resource populations and presents the possibility of using these markers for selective breeding to reduce the numbers of animals with unfavorable meat tenderness traits.

The effects of Piedmontese inheritance and myostatin genotype on the palatability of longissimus thoracis, gluteus medius, semimembranosus, and biceps femoris

The objective of this study was to determine the relative contributions of Piedmontese inheritance (0, 25, 50, or 75%) and myostatin genotype (+/+, mh/+, and mh/mh) to tenderness of four major muscles. Matings were made to produce animals with 0 (+/+), 1 (mh/+), or 2 (mh/mh) inactive myostatin alleles that were known to result in normal muscling, heavy muscling, and extremely heavy muscling, respectively. Over a 4-yr period, 395 steers and heifers (14 to 17 mo of age) were humanely slaughtered and the carcasses were chilled 48 h at 0 degrees C. An eight-member trained descriptive attribute panel evaluated tenderness, ease of fragmentation, connective tissue amount, juiciness, and beef flavor intensity of longissimus thoracis (LD), gluteus medius (GM), semimembranosus (SM), and biceps femoris (BF) steaks at 14 d postmortem. Data were analyzed for the main effects of group (eight combinations of myostatin genotype and percentage Piedmontese; [+/+]/0%, [+/+]/25%, [+/+]/50%, [mh/+]/25%, [mh/+]/50%, [mh/+]/75%, [mh/mh]/50%, [mh/mh]/75%) and muscle. Muscle x group interactions were not significant (P > 0.05). Within myostatin genotypes, contrasts to test the effect of percentage Piedmontese were not significant (P > 0.05). Data were reanalyzed for the main effects of myostatin genotype and muscle. Tenderness, ease of fragmentation, and amount of connective tissue ratings were higher (P < 0.05) for the mh/+ and mh/mh genotypes relative to +/+ in all muscles. In biceps femoris, mh/mh had higher (P < 0.05) tenderness, ease of fragmentation, and amount of connective tissue ratings than the mh/+ genotype. Juiciness ratings were lower (P < 0.05) for mh/mh than for mh/+ in all muscles and were lower for mh/mh than for +/+ in all muscles except gluteus medius. Beef flavor intensity ratings were lower (P < 0.05) for mh/mh than for +/+ in all muscles. Muscle ranks for tenderness within myostatin genotype were LD > GM > SM > BF, LD > GM > SM > BF, LD > GM > BF > SM, for +/+, mh/+, and mh/mh genotypes, respectively. The effects of Piedmontese inheritance on meat tenderness were all due to myostatin genotype. Piedmontese mh/mh bulls could be used as terminal sires to produce mh/+ progeny with improved carcass value due to improved tenderness in the four muscles studied.

A comprehensive search for quantitative trait loci affecting growth and carcass composition of cattle segregating alternative forms of the myostatin gene

The objective of this study was to identify quantitative trait loci for economically important traits in two families segregating an inactive copy of the myostatin gene. Two half-sib families were developed from a Belgian Blue x MARC III (n = 246) and a Piedmontese x Angus (n = 209) sire. Traits analyzed were birth, weaning, and yearling weight (kg); preweaning average daily gain (kg/d); postweaning average daily gain (kg/d); hot carcass weight (kg); fat depth (cm); marbling score; longissimus muscle area (cm2); estimated kidney, pelvic, and heart fat (%); USDA yield grade; retail product yield (%); fat yield (%); and wholesale rib-fat yield (%). Meat tenderness was measured as Warner-Bratzler shear force at 3 and 14 d postmortem. The effect of the myostatin gene was removed using phase information from six microsatellite markers flanking the locus. Interactions of the myostatin gene with other loci throughout the genome were also evaluated: The objective was to use markers in each family, scanning the genome approximately every 25 to 30 centimorgans (cM) on 18 autosomal chromosomes, excluding 11 autosomal chromosomes previously analyzed. A total of 89 markers, informative in both families, were used to identify genomic regions potentially associated with each trait. In the family of Belgian Blue inheritance, a significant QTL (expected number of false-positives = 0.025) was identified for marbling score on chromosome 3. Suggestive QTL for the same family (expected number of false-positives = 0.5) were identified for retail product yield on chromosome 3, for hot carcass weight and postweaning average daily gain on chromosome 4, for fat depth and marbling score on chromosome 8, for 14-d Warner-Bratzler shear force on chromosome 9, and for marbling score on chromosome 10. Evidence suggesting the presence of an interaction for 3-d Warner-Bratzler shear force between the myostatin gene and a QTL on chromosome 4 was detected. In the family of Piedmontese and Angus inheritance, evidence indicates the presence of an interaction for fat depth between the myostatin gene and chromosome 8, in a similar position where the evidence suggests the presence of a QTL for fat depth in the family with Belgian Blue inheritance. Regions identified underlying QTL need to be assessed in other populations. Although the myostatin gene has a considerable effect, other loci with more subtle effects are involved in the expression of the phenotype.

Comprehensive linkage map of bovine chromosome 27

The results of genotypic data contributed to the International Society for Animal Genetics (ISAG) Bovine Chromosome 27 Workshop are presented. Eight laboratories contributed 23 261 informative meioses from 44 loci. Eighteen loci were typed by at least two laboratories and were used to construct a consensus linkage map. Twenty-one loci were subsequently incorporated into a comprehensive map. The sex-averaged consensus map covered 66.9 cM. The sex-averaged comprehensive map was 75.5 cM, while the female and male maps were 73.1 and 63.7 cM, respectively. Five loci were excluded from the analysis because of ambiguous position in the linkage group and a low LOD score (less than 2.0). Average distance between loci in the comprehensive map was 1.98 cM.

Sequence evaluation of four pooled-tissue normalized bovine cDNA libraries and construction of a gene index for cattle

An essential component of functional genomics studies is the sequence of DNA expressed in tissues of interest. To provide a resource of bovine-specific expressed sequence data and facilitate this powerful approach in cattle research, four normalized cDNA libraries were produced and arrayed for high-throughput sequencing. The libraries were made with RNA pooled from multiple tissues to increase efficiency of normalization and maximize the number of independent genes for which sequence data were obtained. Target tissues included those with highest likelihood to have impact on production parameters of animal health, growth, reproductive efficiency, and carcass merit. Success of normalization and inter- and intralibrary redundancy were assessed by collecting 6000-23,000 sequences from each of the libraries (68,520 total sequences deposited in GenBank). Sequence comparison and assembly of these sequences was performed in combination with 56,500 other bovine EST sequences present in the GenBank dbEST database to construct a cattle Gene Index (available from The Institute for Genomic Research at http://www.tigr.org/tdb/tgi.shtml). The 124,381 bovine ESTs present in GenBank at the time of the analysis form 16,740 assemblies that are listed and annotated on the Web site. Analysis of individual library sequence data indicates that the pooled-tissue approach was highly effective in preparing libraries for efficient deep sequencing.

Comprehensive linkage map of bovine chromosome 11

The results of genotypic data contributed to the International Society of Animal Genetics (ISAG) Bovine Chromosome 11 (BTA11) Workshop are presented. Six laboratories contributed a total of 26 199 informative meioses from 80 loci. Thirty-six loci were typed by at least two independent laboratories and were used to construct a consensus linkage map of the chromosome. The remaining loci were subsequently incorporated into a comprehensive map. The sex-averaged consensus map covered 128.9 cM. The female consensus map was 101.2 cM, while the male consensus map was 129.8 cM. The comprehensive sex-averaged map was 134.2 cM and the average genetic distance between loci was 1.72 cM.

Incidence of pericardial effusion in pulmonary tuberculosis

Tuberculosis (TB) is one cause of pericardial disease. In order to know the incidence of tuberculous pericardial effusion (TPE) in patients with pulmonary tuberculosis (PT), the factors associated with their presence and whether human immunodeficiency virus (HIV) patients have a higher risk, we analyzed different parameters and performed an echocardiography to evaluate the presence of TPE. The incidence of TPE was 14.1%, and the presence of pleural effusion was associated with TPE (OR 24.39). HIV patients do not have a higher risk of TPE, independently of immunosuppression. It is necessary to eliminate the presence of TPE in patients with PT, mainly in those with pleural effusion.

Bovine CAPN1 maps to a region of BTA29 containing a quantitative trait locus for meat tenderness

Micromolar calcium activated neural protease (CAPN1) was investigated as a potential candidate gene for a quantitative trait locus (QTL) on BTA29 affecting meat tenderness. A 2,948-bp bovine cDNA containing the entire coding region of the gene was obtained, showing 91% identity to human CAPN1. The 716 AA protein predicted from this sequence shows 97% similarity (95% identity) to the 714 AA human protein. Analysis of the gene structure revealed that CAPN1 mRNA is encoded by at least 19 exons, and 11,055 bp of the gene were sequenced, including 17 introns. Two single nucleotide polymorphisms (SNP) were detected in intron 12 and were used to map bovine CAPN1 to the telomeric end of the BTA29 linkage group. This approximately coincides with the position of the QTL, demonstrating that CAPN1 protease is a positional candidate gene potentially affecting variation in meat tenderness in a bovine resource mapping population.

Prevention of nevirapine-associated exanthema using slow dose escalation and/or corticosteroids

OBJECTIVE

The appearance of rash is one of the most frequent and limiting side-effects during the first 4 weeks of treatment with nevirapine (NVP). We explored the efficacy and safety of four different strategies for reducing the incidence of this complication.

PATIENTS AND METHODS

Four-hundred and sixty-nine patients were assigned randomly to accomplish the induction phase of NVP following either the standard recommendation of 200 mg daily during the first 2 weeks (n = 166), or any of three new strategies: adding prednisone 50 mg each other day during the first 2 weeks (n = 93); using a slowly escalating dose, beginning with 100 mg daily the first week, and increasing the dose by 100 mg/week up to the full daily dose of 400 mg (n = 107); and combining both the addition of prednisone with the slowly escalating dose (n = 103). A pharmacokinetic substudy was performed in seven patients receiving 100 mg of NVP during the first week.

RESULTS

The incidence of rash diminished from 18.7% using the standard recommendation to 9.2% using the alternative approaches (P = 0.003). Rash appeared in 11.2%, 8.6%, and 7.7% of subjects assigned to receive the slowly escalating dose, prednisone, or both, respectively, without significant differences among them. The rate of drug discontinuation was also diminished by one-half using the new approaches (8.5% versus 4.3%; P = 0.06). NVP plasma concentrations within the first week of treatment using 100 mg daily were above the 90% inhibitory concentration for wild-type HIV-1 in all instances.

CONCLUSION

The incidence of rash complicating the first few weeks of treatment with NVP can be diminished by adding corticosteroids for 2 weeks to the standard recommendation, or by using a slowly escalating dose. This second approach is proven to be pharmacokinetically safe.

Quantitative trait loci affecting growth and carcass composition of cattle segregating alternate forms of myostatin

The effects of the bovine myostatin gene on chromosome 2 on birth and carcass traits have been previously assessed. The objective of this study was to identify additional quantitative trait loci (QTL) for economically important traits in two families segregating an inactive copy of myostatin. Two half-sib families were developed from Belgian Blue x MARC III (n = 246) and Piedmontese x Angus (n = 209) sires. Traits analyzed were birth (kg) and yearling weight (kg); hot carcass weight (kg); fat depth (cm); marbling score; longissimus muscle area (cm2); estimated kidney, pelvic, and heart fat (%); USDA yield grade; retail product yield (%); fat yield (%); and wholesale rib-fat yield (%). Meat tenderness was measured as Warner-Bratzler shear force at 3 and 14 d postmortem. The effect of myostatin on these traits was removed by using phase information obtained from the previous study with six microsatellite markers flanking the locus. Selective genotyping was done on 92 animals from both families to identify genomic regions potentially associated with retail product yield and fat depth, using a total of 150 informative markers in each family. Regions in which selective genotyping indicated the presence of QTL were evaluated further by genotyping the entire population and additional markers. For the family with Belgian Blue inheritance (n = 246), a significant QTL for birth and yearling weight was identified on chromosome 6. Suggestive QTL were identified for longissimus muscle area and hot carcass weight on chromosome 6 and for marbling on chromosomes 17 and 27. For the family with Piedmontese inheritance (n = 209), suggestive QTL on chromosome 5 were identified for fat depth, retail product yield, and USDA yield grade and on chromosome 29 for Warner-Bratzler shear force at 3 and 14 d postmortem. Interactions suggesting the presence of QTL were observed between myostatin and chromosome 5 for Warner-Bratzler shear force at 14 d postmortem and between myostatin and chromosome 14 for fat depth. Thus, in families segregating an inactive copy of myostatin in cattle, other loci influencing quantitative traits can be detected. These results are the initial effort to identify and characterize QTL affecting carcass and growth traits in families segregating myostatin.

Different outcomes in patients achieving complete or partial viral load suppression on antiretroviral therapy

BACKGROUND

Potent combination antiretroviral therapy can reduce HIV plasma viral load (VL) to levels below the detection limit for as long as 2 years or more. A VL <500 HIV RNA copies/mL was until recently considered a reasonable therapeutic goal. However, lower levels seem necessary if VL rebounds and development of drug resistance are to be avoided.

PATIENTS AND METHODS

The clinical and virologic outcome at 1 year were prospectively examined in a group of 100 patients who began a triple combination antiretroviral therapy regimen consisting of stavudine (d4T), lamivudine (3TC), and indinavir (IDV). A modified ultrasensitive VL test with a detection limit of 40 copies/mL and a point mutation nested polymerase chain reaction (PCR) assay for detecting the codon 184 mutation conferring 3TC resistance were used for testing samples collected longitudinally from these individuals.

RESULTS

Overall, VL values <40 copies/mL were reached in 45% and 32% of patients at nadir and at 12 months, respectively. More than half (24 of 45 persons) who achieved a level <40 copies/mL at nadir remained with undetectable VL at 1 year, whereas this occurred in only one fourth (7 of 28 persons) of those having levels of 40 to 500 copies/mL (P < .05). However, rebounds in VL to >500 copies/mL at 1 year were seen at similar rates (26.6% and 25%, respectively) in persons achieving either complete (<40 copies/mL) or partial (40-500 copies/mL) VL suppression at nadir. In contrast, the codon 184 mutation emerged more frequently at 1 year in patients whose VL remained between 40 and 500 copies/mL at nadir than in those who reached a level <40 copies/mL (30.7% versus 0%; P < .05).

CONCLUSION

Plasma VL at nadir after beginning highly active antiretroviral therapy (HAART) predicts the 1-year outcome. The achievement of levels of viremia <40 copies/mL are desirable during antiretroviral therapy if prolonged benefit is to be obtained. Because more than two thirds of persons with residual viremia do not show drug resistance, intensification strategies should be investigated for those patients with a good virologic response but without complete suppression during the first 6 months on HAART.

Bovine chromosome 4 workshop: consensus and comprehensive linkage maps

The report of the bovine chromosome 4 (BTA4) workshop is presented. Six laboratories contributed a total of 30,168 informative meioses from 62 loci. Twenty-two loci were typed by at least two independent laboratories and were used to construct a consensus linkage map of BTA4. The remaining 40 loci were subsequently incorporated into a comprehensive map. The sex-averaged consensus map covered 131.4 cM. The female map was 124.3 cM in length, while the male map was 134.3 cM. The comprehensive sex-averaged map spanned 141.6 cM. The length of the female and male comprehensive maps were 123.1 cM and 156.4 cM, respectively. Average genetic distance between loci was 6 and 2.3 cM for the consensus and comprehensive linkage maps, respectively.

[Leishmaniasis: knowledge and practice in populations of the Pacific coast of Colombia]

In 1997 a descriptive study with a qualitative emphasis was carried out in order to document, by gender, the knowledge and practices related to cutaneous leishmaniasis among inhabitants 14 years and older in seven communities of Colombia's Pacific coastal department of Chocó. Since the control activities carried out by the Chocó Sectional Health Services had not had the desired results, the residents of the region were at high risk of contracting leishmaniasis, which they called bejuco (liana) and yateví. Qualitative data were collected by directly involving each community in discussion workshops and by interviewing knowledgeable informants. Using these materials as a foundation, the researchers prepared a survey with 10 closed-ended questions, which they administered to all persons over 14 years of age in each randomly chosen home visited. The results indicate that 94% of the population knew that leishmaniasis appeared as a skin disease; those not knowing that were more often women than men. With respect to the mode of transmission, 35% of the respondents connected the disease to the bite of an insect, but they did not what the etiologic agent was and thought that the bite was inflicted by a worm that lives in the mountains. In the communities studied, the residents used a great variety of treatments to cure the disease. The treatments were based on plants, chemical substances, burning the lesions with a piece of heated metal, and, to a lesser degree, drugs. Despite being responsible for taking care of sick persons in the household, women were not acquainted with the traditional treatments used in the community. This gender difference in treatment knowledge was statistically significant, the only such statistically significant gender difference found in the research. Of the people surveyed, 45% did not know how to prevent the disease. This was more often true for women; 102 of the 155 respondents saying they did not know how to prevent the disease were women. This research emphasizes the importance of studying the knowledge and practices of local inhabitants before designing and organizing educational programs to control leishmaniasis.

Technical note: direct genotyping of the double-muscling locus (mh) in Piedmontese and Belgian Blue cattle by fluorescent PCR

A simple PCR-based allele detection system has been developed to assist in the management of the two most prevalent double-muscled (mh) breeds in the U.S. Application of this assay will permit the implementation of structured mating systems dependent on precise genotypes at the mh locus. The genetic assay uses standard fluorescent genotyping technology and relies on the unique nucleotide composition of wild-type and mutant alleles of myostatin, the gene underlying the double-muscled phenotype. We present data demonstrating the efficacy of this fluorescent primer-based PCR assay in genotyping animal populations carrying normal and(or) mutant alleles of the myostatin gene.

Quantitative analysis of birth, weaning, and yearling weights and calving difficulty in Piedmontese crossbreds segregating an inactive myostatin allele

The Piedmontese breed has a high frequency of double-muscling. Animals tested in this breed are homozygous for a guanine to adenine transition in exon 3 (C313Y) of the myostatin (MSTN) gene. This transition seems to be responsible for the double-muscling phenotype. The objective of this study was to compare effects of alternative MSTN genotypes on proportion of assisted calving and weights at birth, weaning, and 1 yr of age. Reciprocal backcross and F2 calves out of Piedmontese-Angus (PA) and Piedmontese-Hereford (PH) dams born in 1995 (n = 82), 1996 (n = 75), and 1997 (n = 144) were evaluated for birth (BWT, kg), adjusted weaning (W200, kg), and yearling (W365, kg) weights and calving difficulty expressed as a proportion of assisted calving (CD). The number of copies of C313Y was assessed in each calf. Data were analyzed with a model that included effects of year, sex, subclasses of proportion Piedmontese (.25, .5, .75) by number of C313Y copies (0 = +/+, 1 = mh/+, 2 = mh/mh), and age of dam as covariate. For BWT, heterozygous mh/+ animals were 3.2 +/- .8 kg heavier than +/+ animals. Homozygous mh/mh animals increased .19 +/- .06 in proportion of CD compared with mh/+ animals. Differences between homozygous animals (mh/mh - +/+) were 5.2 +/- 1 kg for BWT and .21 +/- .06 for CD. Heterozygous mh/+ animals were 9.1 +/- 4 kg heavier at W200 than homozygous +/+ animals. Homozygous +/+ and heterozygous animals were 20 +/- 8 and 24.5 +/- 8 kg, respectively, heavier at W365 than mh/mh animals. Differences between mh/+ and the mean of mh/mh and +/+ genotypes for W200 and W365 were 8.8 +/- 3 and 18 +/- 5 kg, respectively, suggesting dominance effects on postnatal growth. Production of heterozygous animals, to take advantage of the positive impact of one copy of C313Y on carcass traits, may be a viable option when the value of increased retail product yield is greater than the increased cost associated with calving difficulty.

Changes in cyclin B localisation during pig oocyte in vitro maturation

The localisation of cyclin B throughout in vitro maturation of pig oocytes was determined by indirect immunofluorescence using a monoclonal antibody specific for an epitope of the human cyclin B. Maturation of pig oocytes was induced by addition of Pergonal (2 UI/ml of FSH/LH) and beta-oestradiol to the medium where isolated ovarian follicles were cultured for up to 72 h. Immature gametes with an intact germinal vesicle were observed during the first 30 h of culture. Only 10% were competent to reinitiate meiosis and showed germinal vesicle breakdown (GVBD) after 36 h. However, after 48-72 h, 60% of the oocytes accomplished their maturation and showed metaphase chromosomes. Immature oocytes showed cyclin B immunofluorescent staining in the cytoplasm, whereas mature oocytes showed the immunofluorescent label concentrated in the nucleus. Metaphase chromosomes showed an intense immunofluorescence. The migration of cyclin B to the nucleus and its association with metaphase chromosomes in pig oocytes able to progress through meiosis resembled the subcellular localisation of cyclin B and the distribution of maturation promoting factor (MPF) in mitotic dividing cells.

Sperm plasma membrane receptors for the porcine oocyte plasma membrane

In vitro fertilisation (IVF) was used to assess the ability of solubilised sperm plasma membrane (PM) proteins to inhibit the interaction of intact gametes. This is a first step before evaluating the ability of individual isolated proteins to competitively inhibit sperm-oocyte interaction as part of the process of studying the molecular events of fertilisation. Porcine oocytes were aspirated from ovaries, matured for 48 h in Medium 199, and the zona pellucida (ZP) was removed by exposure to acid Tyrode's solution. ZP-free matured oocytes were exposed to 200-800 micrograms/ml sperm PM protein for 1 h prior to insemination and during gamete co-incubation. Twenty-four hours after insemination with 5 x 10(5) capacitated sperm/ml, the oocytes were fixed, stained and examined. Sperm PM protein clearly inhibited IVF in a concentration-dependent manner (r = -0.87). The inhibition index (I50%), representing the sperm PM protein concentration necessary to inhibit IVF to 50% of the control value, was 310 micrograms/ml. These results demonstrate that solubilised sperm PM protein inhibits the interaction of intact gametes as one might expect for receptor-ligand interactions. Furthermore, the complement of sperm PM proteins appeared maximally effective at a calculated concentration of 690 microns/ml, providing a foundation for further studies with individual proteins.

[Combined antiretroviral therapy for prevention of vertical HIV-1 transmission]

A 25-year old woman with rapid HIV disease progression had been receiving zidovudine (ZDV) for two years, when she became pregnant. She had a high viral load and carried out zidovudine-resistant viral strains. For these reasons, and with the main objective to maximally reduce viremia, the association of DDI to ZDV was introduced a few weeks before delivery. The virological follow-up for one year has confirmed the lack of HIV infection in the child. Combined antiretroviral therapy during the last weeks of pregnancy might be considered for the prevention of vertical transmission of HIV in cases of high risk of newborn infection, without adding relevant toxicity.

Association of the muscle hypertrophy locus with carcass traits in beef cattle

A locus near the centromere of bovine chromosome 2 is responsible for muscle hypertrophy (mh) in cattle. The objectives of this study were to refine the genomic region in which the locus resides and to assess the effects of a single copy of the mh allele on carcass and birth traits. Two half-sib families were developed using a Belgian Blue x MARC III (n = 246) or a Piedmontese x Angus (n = 209) sire. Traits analyzed were calving ease (CE), birth weight (BWT, kg), longissimus rib eye area (REA), retail product yield (RPYD), USDA yield grade (YG), marbling (MAR), fat thickness (FAT), estimated kidney, pelvic, and heart fat (KPH), and longissimus tenderness measured as Warner-Bratzler shear force at 3 (S3) and 14 (S14) d postmortem. Six microsatellites were used to determine the presence or absence of the mh allele and to confirm the location of the locus affecting the traits, which was assessed to be 4 cM from the beginning of the linkage group, with the 95% confidence interval between 2 and 6 cM. Cattle with an mh allele had increased (P < .01) REA, RPYD, and BWT and decreased MAR, YG, FAT, and KPH, compared with those without the allele. The effects of the mh allele (mh/+ vs +/+) were 1.35, 1.6, .41, -1.01, -1.42, -.84, and -.86 residual standard deviations, respectively. There were no effects (P > .10) for CE, S3, and S14. Allelic differences due to the mh locus were similar for both sources (Belgian Blue or Piedmontese). Individuals inheriting a single mh allele had a leaner, more heavily muscled carcass compared with those inheriting the alternative allele. Thus, mating schemes that maximize production of mh/+ genotypes provide a viable approach for improving carcass composition.

In vitro fertilizing capacity of frozen-thawed boar semen

We describe a porcine semen cryopreservation technique and assess the in vitro fertilizing capacity of the frozen-thawed spermatozoa. The thawed spermatozoa did not lose the physiological properties of motility, viability, and acrosome reaction or capacity to fertilize in vitro. Immediately after thawing, the spermatozoa showed 51% mean motility, 60% viability, and 5% induced acrosome reaction. After 2.5 h of incubation in TALP medium, the spermatozoa exhibited 61% motility, 63% viability and 40% induced acrosome reaction. The average in vitro fertilization capacity of thawed spermatozoa was 68% compared with that of spermatozoa from fresh semen (85%). The percentage of polyspermy was highly variable, with frozen-thawed samples ranging from 0 to 28% and fresh samples from 0 to 30%. The results obtained with frozen semen from 5 boars of different breeds did not show considerable variation. This suggests that the freezing-thawing technique is reproducible and adequate for in vitro fertilization.

Intrafamily transmission of hepatitis C virus: sexual and non-sexual contacts

BACKGROUND/METHODS

As a high number of patients with antibodies to hepatitis C (anti-HCV) do not have a known history of parenteral acquisition, other non-parenteral means of hepatitis C virus transmission must be studied. We investigated 1451 household contacts of 535 anti-HCV positive, human immunodeficiency virus-negative index patients.

RESULTS

Overall, the prevalence of anti-HCV in household contacts was 4.5%. Thirty (7.6%) out of the 394 heterosexual stable partners were anti-HCV positive as compared to 35 (3.3%) out of 1057 non-sexual contacts (p < 0.01). The prevalence of anti-HCV was lowest in children of the index cases (1.8%). In this group, the prevalence of anti-HCV was 3% (10/330) when the mother was the index case, as opposed to 0.6% (2/328) when the father was the index case (p < 0.05). The prevalence of anti-HCV increased with age, being highest (18.6%) in family contacts older than 60 years.

CONCLUSIONS

Transmission of hepatitis C virus may occur among household contacts of anti-HCV positive patients. Sexual contact or the use of non-disposable medical material in the past might explain the higher prevalence of anti-HCV found in sexual partners and in family contacts older than 60 years of age. Anti-HCV screening should be performed in family contacts of anti-HCV positive patients, particularly in those contacts older than 20.

Evaluation of different amplification protocols for use in primer-extension preamplification

Different amplification protocols were evaluated for use with primer-extension preamplification (PEP). We hypothesized that a protocol known to improve amplification of long DNA fragments would improve efficacy of PEP. Eight DNA samples were preamplified by PCR using different protocols. Treatments consisted of the use of Taq DNA polymerase (T), Taq plus a second polymerase obtained from Pyrococcus furiosus (E) or Stoffel fragment (S) in PEP. After preamplification, six genetic markers were genotyped, and the number of scorable genotypes was recorded. A control reaction (C) consisted of amplification using genomic DNA as template. A second experiment was performed to evaluate preamplification efficiency using Taq DNA polymerase (5 units) and exponential dilutions of Pfu DNA polymerase. After preamplification, the same procedure was used to obtain a number of scorable genotypes. In the first experiment, treatment E was the most reliable approach for amplifying genomic DNA in PEP. Treatments T and S produced fewer scorable genotypes than treatments E or C. In the second experiment, low concentrations of Pfu DNA polymerase produced a similar percentage of scorable genotypes as higher concentrations. Low concentrations of Pfu DNA polymerase combined with Taq DNA polymerase is the most cost-effective procedure to maximize amplification of limited DNA samples in PEP.

Inhibition of pig oocyte in vitro fertilization by the action of components of the zona pellucida

The aim of the present study was to determine whether the previous addition of porcine zona pellucida (ZP) components to spermatozoa of the same species has an inhibitory effect on in vitro fertilization (IVF). Boar spermatozoa were exposed to whole porcine solubilized zona pellucida (SZP), ZP glycoproteins (55 kDa and 90 kDa) and peptides (37 kDa, 40 kDa and 68kDa). Doses tested were 40, 70 and 100 mug/ml. In vitro fertilization was clearly inhibited by each component when the oocytes were compared with those fertilized with untreated spermatozoa. All the components had an effect in a dose dependent manner.