A partial african ancestry for the creole cattle populations of the Caribbean

Seventy-eight cattle samples from three Creole Caribbean islands and one Brazilian breed were analyzed for sequence variation in the hypervariable segment of the mitochondrial DNA control region. Seventy-three samples displayed Bos taurus haplotypes, and five samples exhibited haplotypes that were of Bos indicus ancestry. Phylogenetic analysis revealed that all sampled B. taurus sequences fell into two distinct clusters with separate African and European origins. European sequences were encountered in each population; however, the distribution of African haplotypes was uneven, with the highest proportion of African influence found in the Guadeloupe Creole. The reduced levels of African haplotypic variation within the Caribbean and Brazilian are consistent with prior founder effects. Additionally, genetic variation at three microsatellite loci illustrated African influence uniquely in the Guadeloupe Creole. Collectively, the data suggest that this African influence is, at least in part, attributable to the historical importation of African cattle to the Americas. Furthermore, alleles of B. indicus ancestry were detected at appreciable frequencies in all Caribbean Creole populations and may reflect zebu introgressions from either West Africa or the Indian subcontinent.

Alteration of C-MYB DNA binding to cognate responsive elements in HL-60 variant cells

AIMS

To establish whether the MYB protein expressed in HL-60 variant cells, which are cells resistant to 12-O-tetradecanoylphorbol-13-acetate (TPA) induced differentiation, is able to bind MYB recognition elements (MREs) involved in the transcriptional regulation of myb target genes. In addition, to determine whether alterations in the binding of the MYB protein to MREs affects HL-60 cell proliferation and differentiation.

METHODS

Nuclear extracts of HL-60 variant cells exhibiting different degrees of resistance to TPA induced monocytic differentiation were used in electrophoretic mobility shift experiments (EMSAs), bandshift experiments performed with labelled oliogonucleotides containing the MYB consensus binding sequences.

RESULTS

The MYB protein contained in nuclear extracts from HL-60 variant cells did not bind efficiently to the MYB recognition elements identified in the mim-1 and PR264 promoters. Molecular cloning of the myb gene and analysis of the MYB protein expressed in the HL-60 variant cells established that the lack of binding did not result from a structural alteration of MYB in these cells. The lack of MRE binding did not abrogate the ability of variant HL-60s to proliferate and to undergo differentiation. Furthermore, the expression of the PR264/SC35 splicing factor was not affected as a result of the altered MYB DNA binding activity.

CONCLUSIONS

Because the MYB protein expressed in HL-60 variant cells did not appear to be structurally different from the MYB protein expressed in parental HL-60 cells, it is possible that the HL-60 variant cells contain a MYB binding inhibitory factor (MBIF) that interferes with MYB binding on MREs. The increased proliferation rate of HL-60 variant cells and their reduced serum requirement argues against the need for direct MYB binding in the regulation of cell growth.

Further contributions to the genetic aspect of congenital sensorineural deafness in Dalmatians

Sensorineural deafness is a common congenital disorder in Dalmatians and is genetically transmitted. Different modes of inheritance have been proposed and the objective of this study was to study these by segregation analyses using maximum likelihood procedures. Data from 33 complete Dalmatian families were collected and data from 56 single Dalmatians added. This resulted in a total of 575 dogs with 357 known phenotypes. All dogs were clinically evaluated and electrophysiologically tested with brainstem auditory evoked responses. The prevalence of deafness was 16.5% (9.4% unilaterally deaf, 7.1% bilaterally deaf). Females were 4.4% more affected than males but this difference was not significant. Within the same litter, different phenotypic expressions of deafness occurred, which suggested different expressions of the disease. In addition, two data sets were analysed: the first included normal, uni- and bilaterally deaf dogs, the second had normal and deaf Dalmatians. We found that a recessive allele at a single biallelic major locus fitted our data best, although an incomplete penetrance of the recessive homozygotes was observed.

An essential residue in the flexible peptide linking the two idiosynchratic domains of bacterial tyrosyl-tRNA synthetases

Tyrosyl-tRNA synthetase (TyrRS) from Bacillus stearothermophilus comprises three sequential domains: an N-terminal catalytic domain, an alpha-helical domain with unknown function, and a C-terminal tRNA binding domain (residues 320-419). The properties of the polypeptide segment that links the alpha-helical and C-terminal domains, were analyzed by measuring the effects of sequence changes on the aminoacylation of tRNA(Tyr) with tyrosine. Mutations F323A (Phe323 into Ala), S324A, and G325A showed that the side chain of Phe323 was essential but not those of Ser324 and Gly325. Insertions of Gly residues between Leu322 and Phe323 and the point mutation L322P showed that the position and precise orientation of Phe323 relative to the alpha-helical domain were important. Insertions of Gly residues between Gly325 and Asp326 and deletion of residues 330-339 showed that the length and flexibility of the sequence downstream from Gly325 were unimportant but that this sequence could not be deleted. Mutations F323A, -L, -Y, and -W showed that the essential property of Phe323 was its aromaticity. The Phe323 side chain contributed to the stability of the initial complex between TyrRS and tRNA(Tyr) for 2.0 +/- 0.2 kcal x mol(-1) and to the stability of their transition state complex for 4.2 +/- 0.1 kcal x mol(-1), even though it is located far from the catalytic site. The results indicate that the disorder of the C-terminal domain in the crystals of TyrRS is due to the flexibility of the peptide that links it to the helical domain. They identified Phe323 as an essential residue for the recognition of tRNA(Tyr).

Estimation of genetic population variables for six radiographic criteria of hip dysplasia in a colony of Labrador Retrievers

OBJECTIVE

To estimate genetic population variables for 6 radiographic criteria of canine hip dysplasia (CHD).

ANIMALS

664 full- and half-siblings from a colony of Labrador Retrievers.

PROCEDURE

Heritability estimates and genetic correlations were calculated for 6 radiographic criteria of CHD. Two evaluation protocols were compared: the grade of the most severely affected hip joint and the sum of the scores for both hip joints. The predictive performance of estimated breeding values was also evaluated.

RESULTS

The overall prevalence of CHD (Federation Cynologique Internationale grades C, D, and E) was 29.6%. Median age at radiographic examination was 377 days. Heritability for the total CHD grade, Norberg angle (NA), coverage of the femoral head (COV), craniodorsal acetabular rim (ACR), subchondral bone sclerosis (SUBCH), shape of the femoral head and neck (FHN), and osteoarthritic changes at the insertion site of the joint capsule (JC) was estimated as follows: 0.44, 0.43, 0.46, 0.37, 0.32, 0.21, and 0.05, respectively. Heritability estimates were slightly higher for the sum of the scores for both hip joints. If NA and COV were included as fixed effects in the model for the dependent variables ACR, SUBCH, FHN, and JC , then heritability of these traits significantly decreased (0.08 to 0.15). High scores of NA and COV lead to a significant increase of the scores of the remaining criteria.

CONCLUSIONS AND CLINICAL RELEVANCE

Canine hip dysplasia is heritable to a moderate degree. Signs of subluxation revealed the highest heritability estimates. The criteria ACR, SUBCH, FHN, and JC were strongly influenced by NA and COV.

Identification of epistatic interactions involved in non-insulin-dependent diabetes mellitus in the Otsuka Long-Evans Tokushima Fatty rat

The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an animal model for obese-type non-insulin-dependent diabetes mellitus (NIDDM) in humans. Our present investigation was designed to identify epistatic interactions influencing NIDDM by performing least squares analysis of variance of all pairs of informative markers in 160 F2 progenies bred from an intercross of OLETF and Fischer-344 rats. We identified four interactions between Nidd15/of (chromosome 7) and Nidd16/of (chromosome 14), Nidd15/of and Nidd17/of (chromosome 15), Nidd16/of and Nidd18/of (chromosome 15), and Nidd16/of and Nidd19/of (chromosome 17), which account for a total of approximately 40% of the genetic variation of entire glucose levels after glucose challenge in the F2. The Nidd16/of locus, which is involved in three of four digenic interactions, and the Nidd19/of are likely to correspond to Nidd2/of and Nidd14/of, NIDDM loci previously identified in the F2 by single-QTL model and multiple-QTL model, respectively, while Nidd15/of, Nidd17/of and Nidd18/of loci reflect novel NIDDM loci. An aberrant increase of the entire glucose level due to synergism occurs in the double OLETF homozygote genotype of Nidd15/of and Nidd16/of, and of Nidd16/of and Nidd19/of, as well as in the OLETF homozygote genotypes of Nidd15/of and Nidd16/of, respectively, combined with the heterozygote genotypes of Nidd17/of and Nidd18/of. These findings demonstrate that inter-allelic interactions are likely to be an important component of NIDDM susceptibility.

Variant esp gene as a marker of a distinct genetic lineage of vancomycin-resistant Enterococcus faecium spreading in hospitals

In the USA, vancomycin-resistant Enterococcus faecium (VREF) is endemic in hospitals, despite lack of carriage among healthy individuals. In Europe, however, hospital outbreaks are rare, but VREF carriage among healthy individuals and livestock is common. We used amplified fragment-length polymorphism analysis to genotype 120 VREF isolates associated with hospital outbreaks and 45 non-epidemic isolates from the USA, Europe, and Australia. We also looked for the esp virulence gene in these isolates and in 98 VREF from animals. A specific E. faecium subpopulation genetically distinct from non-epidemic VREF isolates was found to be the cause of the hospital epidemics in all three continents. This subpopulation contained a variant of the esp gene that was absent in all non-epidemic and animal isolates. Identification of the variant esp gene will be important in guiding infection-control strategies, and the Esp protein could be a new target for antibacterial therapy.

Molecular determinants by which a long chain toxin from snake venom interacts with the neuronal alpha 7-nicotinic acetylcholine receptor

Long chain curarimimetic toxins from snake venom bind with high affinities to both muscular type nicotinic acetylcholine receptors (AChRs) (K(d) in the pm range) and neuronal alpha 7-AChRs (K(d) in the nm range). To understand the molecular basis of this dual function, we submitted alpha-cobratoxin (alpha-Cbtx), a typical long chain curarimimetic toxin, to an extensive mutational analysis. By exploring 36 toxin mutants, we found that Trp-25, Asp-27, Phe-29, Arg-33, Arg-36, and Phe-65 are involved in binding to both neuronal and Torpedo (Antil, S., Servent, D., and Ménez, A. (1999) J. Biol. Chem. 274, 34851-34858) AChRs and that some of them (Trp-25, Asp-27, and Arg-33) have similar binding energy contributions for the two receptors. In contrast, Ala-28, Lys-35, and Cys-26-Cys-30 selectively bind to the alpha 7-AChR, whereas Lys-23 and Lys-49 bind solely to the Torpedo AChR. Therefore, alpha-Cbtx binds to two AChR subtypes using both common and specific residues. Double mutant cycle analyses suggested that Arg-33 in alpha-Cbtx is close to Tyr-187 and Pro-193 in the alpha 7 receptor. Since Arg-33 of another curarimimetic toxin is close to the homologous alpha Tyr-190 of the muscular receptor (Ackermann, E. J., Ang, E. T. H., Kanter, J. R., Tsigelny, I., and Taylor, P. (1998) J. Biol. Chem. 273, 10958-10964), toxin binding probably occurs in homologous regions of neuronal and muscular AChRs. However, no coupling was seen between alpha-Cbtx Arg-33 and alpha 7 receptor Trp-54, Leu-118, and Asp-163, in contrast to what was observed in a homologous situation involving another toxin and a muscular receptor (Osaka, H., Malany, S., Molles, B. E., Sine, S. M., and Taylor, P. (2000) J. Biol. Chem. 275, 5478-5484). Therefore, although occurring in homologous regions, the detailed modes of toxin binding to alpha 7 and muscular receptors are likely to be different. These data offer a molecular basis for the design of toxins with predetermined specificities for various members of the AChR family.

Phylogenetic analysis of the tribe Bovini using microsatellites

The objective of the present study was to determine if the generally accepted phylogenetic relationships in the tribe Bovini correspond to a phylogenetic scheme derived from polymorphisms at 20 bovine microsatellite loci. This study comprises 17 representative populations: eight Bos taurus, two Bos indicus, one Poëphagus, one Bibos, one Bison, three Bubalus and one Syncerus. Phylogenetic analyses using (delta mu)2 and chord (DC) distances revealed substantial divergence among species. Neighbor-joining trees with both distance measures showed only minor differences. Bos taurus and Bos indicus grouped first, followed by Bos frontalis (Mithan) and Bos grunniens (Yak), Bison bison branched off next and Bubalus bubalis and Syncerus caffer emerged as the two most divergent species from the Bos clade. These findings would suggest that Bos, Poëphagus, and Bibos should be integrated into the Bos genus with each group classified as a subgenus. On the other hand, Bison, Bubalus and Syncerus should each be considered a separate genus. Direct estimates of the divergence times were calculated using the (delta mu)2 genetic distance. Bos taurus and Bos indicus were estimated to have diverged 0.31-0.82 MYA, Bos and Poëphagus: 0.57-1.53 MYA, Bos and Bibos: 0.57-1.52 MYA, Bos and Bison: 0.46-1.23 MYA, Bos and Bubalus: 1.85-4.93 MYA and Bos and Syncerus: 0.98-2.61 MYA.

Y-specific microsatellite polymorphisms in a range of bovid species

At least five dinucleotide (CA)n microsatellite repeat arrays have been assigned to the bovine Y-chromosome, with one marker (INRA124) shown to be polymorphic. We describe here the assessment of a panel of four Y-specific microsatellite markers for polymorphism in a range of cattle and related species. It was possible to amplify all the markers in the animals sampled and all showed variation. Three of the microsatellite loci (INRA124, INRA189 and BM861) displayed putative taurine- and zebu-specific alleles which can be useful indicators of male-mediated gene flow in hybrid populations. In the future these microsatellites, in combination with other Y-specific markers should provide a high-resolution Y haplotype system for evolutionary studies in both domesticated cattle and other related species.

Molecular characterization of the specificity of interactions of various neurotoxins on two distinct nicotinic acetylcholine receptors

Snake curaremimetic toxins are currently classified as short-chain and long-chain toxins according to their size and their number of disulfide bonds. All these toxins bind with high affinity to muscular-type nicotinic acetylcholine receptor, whereas only long toxins recognize the alpha7 receptor with high affinity. On the basis of binding experiments with Torpedo or neuronal alpha7 receptors using wild-type and mutated neurotoxins, we characterized the molecular determinants involved in these different recognition processes. The functional sites by which long and short toxins interact with the muscular-type receptor include a common core of highly conserved residues and residues that are specific to each of toxin families. Furthermore, the functional sites through which alpha-cobratoxin, a long-chain toxin, interacts with muscular and alpha7 receptors share similarities but also marked differences. Our results reveal that the three-finger fold toxins have evolved toward various specificities by displaying distinct functional sites.

Association of double-stranded DNA fragments into multistranded DNA structures

We have previously observed that double-stranded DNA fragments containing a tract of the tandemly repeated sequence poly(CA). poly(TG) can associate in vitro to form stable complexes of low electrophoretic mobility, which are recognized with high specificity by proteins HMG1 and HMG2. The formation of such complexes has since been observed to depend on interactions of DNA with polypropylene surfaces, with the suggestion that the formation of low mobility complexes might be the result of strand dissociation followed by misaligned reassociation of the repetitive sequences. The data presented here show that at high ionic strength the interactions of DNA with polypropylene are sufficiently strong for DNA to remain bound to the polypropylene surface, which suggests that DNA might also be involved in interactions with hydrophobic molecules in vivo. Under such conditions, low-mobility complexes are found only in the material adsorbed to the polypropylene surface, and all DNA fragments are able to form low-mobility structures, whether or not they contain repetitive sequences. Preventing the separation of strands by ligating hairpin loop oligonucleotides at both ends of the fragments does not prevent the formation of low-mobility complexes. Our results suggest two different pathways for the formation of complexes. In the first, dissociation is followed by misaligned reassociation of repetitive sequences, yielding duplexes with single-stranded end regions that associate to form multimeric complexes. In the second, repetitive as well as nonrepetitive DNA molecules bound to polypropylene adopt a conformation with locally unwound regions, which allows interactions between neighboring duplexes adsorbed on the surface, resulting in the formation of low-mobility complexes.

Prevalence and infection risks of zoonotic enteropathogenic bacteria in Swiss cow-calf farms

A longitudinal study was performed in 67 larger Swiss cow-calf farms from September 1996 through November 1997. The objectives of the study were to estimate prevalence and risk factors for colonization with potentially zoonotic enteropathogenic bacteria in younger calves and in calves at weaning age. The study included data from 395 calves with three to four fecal samples each. Fecal samples were analyzed for Campylobacter spp., verotoxin producing E. coli (VTEC), Yersinia spp. and Salmonella sp. Possible environmental and individual factors associated with colonization of these agents were examined. The calves were housed indoor during the first 3 months of life (winter 1996/1997). The prevalences within this time period were: C. coli 3.4%, C. fetus 15.5%, C. hyointestinalis 9.6%, C. jejuni 38.5%, VTEC 44.3% and Yersinia spp. 2%. At the end of the grazing season the prevalences at weaning (8-10 months of age) were: C. coli 1.7%, C. fetus 4.0%, C. hyointestinalis 25.9%, C. jejuni 13.3%, VTEC 38.2% and Yersinia spp. 0%. No salmonellae were present at any time of the study. The prevalences of C. jejuni and VTEC increased significantly within the first 3 months of life, whereas C. hyointestinalis decreased. None of the environmental factors such as housing or feeding had any consistent influences on colonization by the bacteria studied. VTEC, Campylobacter spp. and Yersinia spp. should probably be considered as normal inhabitants of the bovine intestinal tract. However, as they represent a source of gastrointestinal infections in humans, management factors limiting intestinal colonization of these bacteria should be considered in cow-calf operations.

Identification of a pollen-specific sucrose transporter-like protein NtSUT3 from tobacco

Pollen cells are symplasmically isolated during maturation and germination. Pollen therefore needs to take up nutrients via membrane carriers. Physiological measurements on pollen indicate sucrose transport in the pollen tube. A cDNA encoding a pollen-specific sucrose transporter-like protein NtSUT3 was isolated from a tobacco pollen cDNA library. NtSUT3 expression is detected only in pollen and is restricted to late pollen development, pollen germination and pollen tube growth. Altogether these data indicate that pollen is supplied not only with glucose, but also with sucrose through a specific sucrose transporter. The respective contribution of each transport pathway may change during pollen tube growth.

[General review of the value of hepatic MRI in the diagnosis and preoperative staging of liver metastasis from colon and rectum cancer]

Hepatic resection of secondary liver neoplasms is currently the only potentially curative therapy for patients with primary colorectal carcinoma. Long-term survival is closely related to stage, regardless of the number, size and distribution of liver lesions. Preoperative detection of liver metastases is crucial in patient staging and imaging techniques must be as accurate as possible to evaluate whether hepatic resection can be performed. Among the various strategies applied to the preoperative detection of liver metastases, CT with intra-arterial portography (CTAP) has been found to be the most sensitive technique. It is an invasive evaluation with a reported sensitivity ranging from 81 to 94% but with 6 to 15% of false-positive results. Recent studies demonstrate that MRI with superparamagnetic iron oxide has an equivalent sensitivity and specificity to CTAP. This paper reviews the technique of MRI, evaluates its sensitivity and specificity, and presents the advantages and draw backs of the technique.

Clinical and genetic investigations of idiopathic epilepsy in the Bernese mountain dog

A study was conducted to investigate the clinical aspects and to define the mode of inheritance of idiopathic epilepsy in the Bernese mountain dog. Pedigree analyses were carried out on an open, non-preselected population of 4005 dogs. Five different subpopulations with 50 epileptic dogs from 13 generations were included. Almost all epileptic patients showed generalised seizures of the grand-mal type with a well-defined prodromal and postictal phase. The majority (62 per cent) of the epileptic dogs had had their first seizures at between one and three years of age and it was found that the age at first seizure was significantly (P < 0.05) lower in dogs from affected parental animals than in dogs from healthy parental animals. A clear predisposition for males was also noted. Additionally, there was no correlation between inbreeding coefficient and age at first seizure or incidence rate of seizures. The increased occurrence of the disease in different subpopulations and different families of the same sires or dams showed that there was a genetic basis for the condition in the Bernese mountain dog. Furthermore, the results of the pedigree analyses and binomial test support the hypothesis that idiopathic epilepsy has a polygenic, recessive mode of inheritance in the breed. Additional objective test-mating programmes would however be necessary to define the exact mode of inheritance.

[Prevalence and importance of endoparasites in calves raised in Swiss cow-calf farms]

A longitudinal study was performed to establish estimates of prevalence of selected endoparasites in Swiss cow-calf operations and to investigate the importance of an infection with endoparasites on diarrhea and weight gain until weaning. Three hundred and eighty-six calves raised in 67 larger cow-calf herds were included in the study. Faecal samples were collected during the first three months of life and at weaning. Parasitological analyses were performed according to standard procedures including specifically the detection of Eimeria spp., Cryptosporidium parvum, Strongyloides papillosus and Trichostrongylida. The effects of an infection with endoparasites on weight gain were analyzed with a linear model accounting for effects of farm, breed, sex, calving month and weight at birth. The average prevalences of endoparasites within the first three months of life were: E. bovis 36%, E. zuernii, 19%, C. parvum 16.8%, S. papillosus 22.3% and Trichostrogylida 1.5%. The prevalence of diarrhea within the same time period was 13%. Prevalences at weaning (at the end of the grazing period) were: E. bovis 56.5%, E. zuernii 4.6%, C. parvum 3.7%, S. papillosus 14.4% and Trichostrogylida 84.5%. With the exception of E. zuernii, endoparasites were more frequently observed in healthy calves than in diarrheic calves. Weaning weights were available from 190 calves (33 herds). Statistical analyses of weaning weights revealed no evidence that an infection with helminths and/or protozoa within the first three months of life or at weaning had a negative influence on individual weight gain.