Holstein Friesian dairy cattle edited for diluted coat color as a potential adaptation to climate change

BACKGROUND

High-producing Holstein Friesian dairy cattle have a characteristic black and white coat, often with large proportions of black. Compared to a light coat color, black absorbs more solar radiation which is a contributing factor to heat stress in cattle. To better adapt dairy cattle to rapidly warming climates, we aimed to lighten their coat color by genome editing.

RESULTS

Using gRNA/Cas9-mediated editing, we introduced a three bp deletion in the pre-melanosomal protein 17 gene (PMEL) proposed as causative variant for the semi-dominant color dilution phenotype observed in Galloway and Highland cattle. Calves generated from cells with homozygous edits revealed a strong color dilution effect. Instead of the characteristic black and white markings of control calves generated from unedited cells, the edited calves displayed a novel grey and white coat pattern.

CONCLUSION

This, for the first time, verified the causative nature of the PMEL mutation for diluting the black coat color in cattle. Although only one of the calves was healthy at birth and later succumbed to a naval infection, the study showed the feasibility of generating such edited animals with the possibility to dissect the effects of the introgressed edit and other interfering allelic variants that might exist in individual cattle and accurately determine the impact of only the three bp change.

Feeding forage or concentrates early in life influences rumen fermentation, metabolic response, immune function and growth of Wagyu × Friesian calves

Context Early life nutrition of calves influences their performance later in life. There is limited literature demonstrating the effects of rearing dairy calves in early life on milk with either exclusively forage or concentrate starter diets on metabolic and immune function and post-weaning growth and body composition on a pasture only diet. Aim This study evaluated the effects of feeding Wagyu × Holstein Friesian calves a forage starter (FS) or a concentrate starter (CS) for the first 14 weeks of rearing on rumen fermentation, blood metabolites, immune function, growth and body composition to Week 41. Methods Group-housed calves (Wagyu × Friesian, 10 calves per group, three groups per treatment) were fed milk (2 L per calf twice daily) until Week 7, then transitioned to once a day milk feeding until weaning by Week 9, with ad libitum access to either FS or CS. All calves were transferred to graze ryegrass pastures a week after transitioning to once daily milk feeding, with starter feeds removed gradually by Week 14. Thereafter, calves were reared together on pasture until Week 41. Results Solid feed intake was lower in FS than CS calves during the first 7 weeks. Total short chain fatty acids were lower, but acetate to propionate ratio and rumen pH were higher in FS than CS calves at Week 7, with no differences observed at Week 12 or 30. Plasma β-hydroxybutyrate an indicator of ketogenic ability of the rumen in developing calves was higher in FS vs CS calves at weaning. Further, FS calves had lower concentrations of circulating non-esterified fatty acids compared with CS calves at weaning. Compared with CS calves, FS calves grew slower for the first 14 weeks which was associated with lower plasma IGF-1 levels. However, FS calves had greater average daily gain after 14 weeks when on pasture and had similar plasma IGF-1 at 30 weeks and similar body weight and body composition (muscle and subcutaneous fat deposition) by Week 41 compared to CS calves. Conclusions These results indicate that offering a FS starter has better prepared calves for weaning onto pasture and potentially improved utilisation of forage post-weaning to achieve similar muscle and fat deposition and overall liveweight in both groups by 41 weeks. Implications Dairy beef calves can be successfully reared using forage as the only solid feed source without affecting their growth performance on pasture until 10 months of age. Rearing calves using forage will contribute to reducing the usage of concentrate feeds in pastoral dairy-beef production systems and provide an opportunity to fulfil the market requirements and standards for grain-free beef production.

Effect of weaning age on growth, mammary gland development, and immune function in Holstein Friesian calves fed conserved alfalfa (FiberStart)

This study aimed to evaluate intake, body growth, and the development of the rumen, mammary gland, and immune system in Holstein Friesian calves reared for 100 d on the commercially available feed FiberStart (conserved alfalfa, Medicago sativa; Fiber Fresh Feeds Ltd., Reporoa, New Zealand) and fed calf milk replacer (CMR) for either 56 or 91 d. Eighty calves (40 bulls and 40 heifer calves) were reared indoors in groups (n = 5 of the same sex/pen). All calves were fed 4 L of CMR/d (175 g/L of CMR) in 2 feeds/d for the first 10 d and then 1 feed/d until d 49 or 84. The calves were gradually weaned by d 56 (earlier weaned; n = 8 pens) and d 91 (later weaned; n = 8 pens). All calves were fed FiberStart ad libitum as the only solid feed source from d 1 to 100 of the study. Irrespective of treatment, all calves had similar body weights at d 0 (40.9 ± 3.0 kg) and d 49 (74.2 ± 5.1 kg) of the study. Calf sex had no effect on intake, growth, blood, and immune system parameters. Earlier-weaned calves consumed 18% more solid feed dry matter but had 16% lower body weight gain (28.9 vs. 38.5 kg, respectively) from d 56 to 100 relative to later-weaned calves, resulting in different body weight at 100 d (104 vs. 121 ± 1.3 kg). Although earlier-weaned calves could compensate for the loss of CMR dry matter and crude protein intake from d 56 to 100 by increasing forage intake, they were unable to compensate for the loss of energy from the CMR by increasing solid feed consumption. Plasma β-hydroxybutyrate concentrations were 52% greater in earlier-weaned calves than in later-weaned calves at d 84, indicating greater metabolic activity of the rumen wall. The duration of CMR feeding had no influence on humoral or cell-mediated immune functions of the calves, as evidenced by a lack of effect on antivaccine antibody responses as well as on immune gene expression. Earlier- versus later-weaned heifer calves had 5% lower mammary gland mass, indicating that greater energy supply increased mammary mass. The results of this experiment demonstrate the ability to artificially rear dairy calves on a conserved alfalfa as the only solid feed. Furthermore, earlier weaning off CMR promotes solid feed intake and an associated increase in blood β-hydroxybutyrate, an indicator of rumen development, but increasing the duration of CMR feeding improves growth and mammary gland mass by d 100. The implications of these findings on lifetime growth, health, and milk production in dairy heifers warrant further investigation.

Chromosomal location of Pm35, a novel Aegilops tauschii derived powdery mildew resistance gene introgressed into common wheat (Triticum aestivum L.)

A single gene controlling powdery mildew resistance was identified in the North Carolina germplasm line NC96BGTD3 (NCD3) using genetic analysis of F(2) derived lines from a NCD3 X Saluda cross. Microsatellite markers linked to this Pm gene were identified and their most likely order was Xcfd7, 10.3 cM, Xgdm43, 8.6 cM, Xcfd26, 11.9 cM, Pm gene. These markers and the Pm gene were assigned to chromosome 5DL by means of Chinese Spring Nullitetrasomic (Nulli5D-tetra5A) and ditelosomic (Dt5DL) lines. A detached leaf test showed a distinctive disease reaction to six pathogen isolates among the NCD3 Pm gene, Pm2 (5DS) and Pm34 (5DL). An allelism test showed independence between Pm34 and the NCD3 Pm gene. Together, the tests provided strong evidence for the presence of a novel Pm gene in NCD3, and this gene was designated Pm35.

Pm34: a new powdery mildew resistance gene transferred from Aegilops tauschii Coss. to common wheat (Triticum aestivum L.)

Powdery mildew is a major fungal disease in wheat growing areas worldwide. A novel source of resistance to wheat powdery mildew present in the germplasm line NC97BGTD7 was genetically characterized as a monogenic trait in greenhouse and field trials using F(2) derived lines from a NC97BGTD7 X Saluda cross. Microsatellite markers were used to map and tag this resistance gene, now designated Pm34. Three co-dominant microsatellite markers linked to Pm34 were identified and their most likely order was established as: Xbarc177-5D, 5.4cM, Pm34, 2.6cM, Xbarc144-5D, 14cM, Xgwm272-5D. These microsatellite markers were previously mapped to the long arm of the 5D chromosome and their positions were confirmed using Chinese Spring nullitetrasomic Nulli5D-tetra5A and ditelosomic Dt5DL lines. Pm2, the only other known Pm gene on chromosome 5D, has been mapped to the short arm and its specificity is different from that of Pm34.

Effect of Inoculation with Selected Isolates of Stagonospora nodorum on Field Evaluations of Host Resistance in Winter Wheat

Although Stagonospora nodorum blotch occurs annually in North Carolina, selection for resistance in wheat (Triticum aestivum) breeding nurseries is hampered by the infrequent occurrence of heavy and timely disease pressure. The objective of this study was to compare estimates of host resistance in a population of 147 random winter wheat lines evaluated in epidemics produced by natural infection versus epidemics supplemented by inoculation with selected isolates. Two isolates were chosen from a set of 43 collected in North Carolina based on their aggressiveness on four wheat cultivars in a controlled environment test. Field experiments utilized a split-plot design with three replications. The main plots were inoculation treatments and the subplots were the 147 wheat genotypes. The inoculation treatments were (i) selected isolate A (more aggressive) alone, (ii) selected isolate B (less aggressive) alone, (iii) a combination of isolates A plus B, and (iv) natural infection. Selected isolate treatments were applied at Feekes growth stage 9 to 10.1, and disease intensity was measured two or three times at 14-day intervals postinoculation. The study was conducted at one location in the 1996-97 season and two locations in the 1997-98 season. High levels of natural infection occurred, and no differences were observed among the four inoculation treatments for mean disease intensity in any of the three environments. Within environments, genotype-by-inoculation treatment variance was significant in the two environments inoculated with selected isolates at growth stage 9 but not in the environment inoculated at growth stage 10.1. Magnitudes of genetic variation and heritability for Stagonospora nodorum blotch resistance were not consistently associated with main plot treatments, and inoculation with selected isolates masked genetic variation for resistance in two treatments in one environment. Genotype rank correlations for Stagonospora nodorum blotch resistance between inoculation treatments varied from zero to 0.69 within environments, but only a single correlation between inoculation treatments in different environments was observed. Estimates of host resistance in epidemics supplemented with selected isolates did not consistently agree with estimates in epidemics produced by natural infection. Our results did not support the routine use of supplemental inoculation of wheat breeding nurseries with selected isolates of S. nodorum as a means of increasing genetic gain for host resistance.

A major gene for powdery mildew resistance transferred to common wheat from wild einkorn wheat

ABSTRACT A major gene for resistance to wheat powdery mildew (Blumeria graminis f. sp. tritici = Erysiphe graminis f. sp. tritici) has been successfully transferred into hexaploid common wheat (Triticum aestivum, 2n = 6x = 42, AABBDD) from wild einkorn wheat (Triticum monococcum subsp. aegilopoides, 2n = 2x = 14, AA). NC96BGTA5 is a germ plasm line with the pedigree Saluda x 3/PI427662. The response patterns for powdery mildew resistance in NC96BGTA5 were tested with 30 differential isolates of B. graminis f. sp. tritici, and the line was resistant to all tested isolates. The analyses of P(1), P(2), F(1), F(2), and BC(1)F(1) populations derived from NC96BGTA5 revealed two genes for wheat powdery mildew resistance in the NC96BGTA5 line. One gene, Pm3a, was from its recurrent parent Saluda, and the second was a new gene introgressed from wild einkorn wheat. The gene was determined to be different from Pm1 to Pm21 by gene-for-gene and pedigree analyses. The new gene was identified as linked to the Pm3a gene based on the F(2) and BC(1)F(1) populations derived from a cross between NC96BGTA5 and a susceptible cultivar NK-Coker 68-15, and the data indicated that the gene was located on chromosome 1A. It is proposed that this new gene be designated Pm25 for wheat powdery mildew resistance in NC96BGTA5. Three random amplified polymorphic DNA markers, OPX06(1050), OPAG04(950), and OPAI14(600), were found to be linked to this new gene.

Systemic immunization with conserved pilus-associated adhesins protects against mucosal infections

Colonization and infection of the bladder mucosa by Escherichia coli, the major uropathogenic organism, is dependent on the expression of pilus organelles. Type 1 pili are expressed by the majority of E. coli strains derived from patients with cystitis and pyelonephritis. FimH is the adhesin protein located at the distal tip of the heteropolymeric type-1 pilus which mediates binding to bladder cells through mannose receptors. We have shown that humoral antibody raised against two forms of purified FimH adhesin inhibited 94% (49/52) of E. coli UTI clinical isolates from binding to bladder tissue in vitro. Animals immunized with FimH-containing vaccines by a systemic route reduced colonization of the bladder mucosa in vivo in a murine cystitis model by > 99%. IgG antibody to FimH was detected in urinary samples obtained from immunized, protected mice. Passive systemic administration of immune sera from FimH-inoculated mice to naive animals also resulted in reduced colonization of bladder mucosa by uropathogenic E. coli. These studies demonstrate that systemic immunization with an anti-bacterial vaccine targeting a highly conserved adhesin on uropathogenic E. coli can induce IgG-mediated protection at a mucosal surface and may be a means of preventing recurrent and acute infections of the urogenital tract mucosa.

Virulence of Blumeria graminis f. sp. tritici on Winter Wheat in the Eastern United States

Samples of perithecia of Blumeria graminis f. sp. tritici from senescing wheat leaves were collected by cooperators from 17 states. Ascospores were discharged from perithecia and single-spore isolates were characterized for virulence genes using a differential host series containing 15 known resistance genes. A total of 520 isolates from 17 states were characterized in 1993 and 1994. Virulence frequencies and complexity and racial composition were examined. The data were analyzed for associations among sets of virulence genes and the geographical distribution of phenotypes. Virulence to Pm3c, Pm3f, pm5, Pm6, and Pm7 was present in all states surveyed. Since 1990, virulence to Pm3a has increased in the northeast, and virulence to Pm1, Pm4b, Pm8, and Pm17 has increased across the area surveyed. The resistance genes Pm12 and Pm16 remain highly effective in the southeastern United States. An increase in virulence frequencies and complexity of isolates was observed.

Prevention of mucosal Escherichia coli infection by FimH-adhesin-based systemic vaccination

Virtually all uropathogenic strains of Escherichia coli, the primary cause of cystitis, assemble adhesive surface organelles called type 1 pili that contain the FimH adhesin. Sera from animals vaccinated with candidate FimH vaccines inhibited uropathogenic E. coli from binding to human bladder cells in vitro. Immunization with FimH reduced in vivo colonization of the bladder mucosa by more than 99 percent in a murine cystitis model, and immunoglobulin G to FimH was detected in urinary samples from protected mice. Furthermore, passive systemic administration of immune sera to FimH also resulted in reduced bladder colonization by uropathogenic E. coli. This approach may represent a means of preventing recurrent and acute infections of the urogenital mucosa.

Transfer of HIV-1-specific cytotoxic T lymphocytes to an AIDS patient leads to selection for mutant HIV variants and subsequent disease progression

An HIV-1-seropositive volunteer was infused with an expanded autologous cytotoxic T lymphocyte (CTL) clone directed against the HIV-1 nef protein. This clone was adoptively transferred to determine whether supplementing CTL activity could reduce viral load or improve clinical course. Unexpectedly, infusion was followed by a decline in circulating CD4+ T cells and a rise in viral load. Some of the HIV isolates obtained from the plasma or CD4+ cells of the patient were lacking the nef epitope. These results suggest that active CTL selection of viral variants could contribute to the pathogenesis of AIDS and that clinical progression can occur despite high levels of circulating HIV-1-specific CTLs.

Cloned human CD8+ cytotoxic T lymphocytes protect human peripheral blood leukocyte-severe combined immunodeficient mice from HIV-1 infection by an HLA-unrestricted mechanism

The ability to infect human peripheral blood leukocyte-reconstituted severe combined immunodeficient (hu-PBL-SCID) mice with HIV has allowed evaluation of several strategies for preventing or treating infection. In one study, hu-PBL-SCID mice derived from HIV gp160-vaccinated donors were shown to resist HIV infection, and resistance correlated best with in vitro assays of cellular immunity. We have assessed directly the importance of cellular immunity to HIV in the present experiments by the adoptive transfer of HLA-A3-restricted HIV-1 Nef-specific or HLA-B14-restricted Gag-specific CD8+ CTL clones to SCID mice bearing HLA-matched or mismatched PBL grafts. Multiple inoculations of CTL before and after HIV-1 exposure protected HLA-matched hu-PBL-SCID mice from infection, but initiation of CTL therapy on the same day as HIV infection was much less effective. However, at the high numbers of CTL required for complete protection from HIV infection, many HLA-mismatched hu-PBL-SCID mice were also protected by pre-exposure CTL transfer. Transfer of CTL with a different specificity (HTLV-1 Tax) to HLA-matched hu-PBL-SCID mice also afforded partial protection. These results suggest that HLA-restricted cytotoxicity may be less important than other nonspecific effector mechanisms for the inhibition of HIV-1 infection in vivo.

Cloned human CD8+ cytotoxic T lymphocytes protect human peripheral blood leukocyte-severe combined immunodeficient mice from HIV-1 infection by an HLA-unrestricted mechanism

The ability to infect human peripheral blood leukocyte-reconstituted severe combined immunodeficient (hu-PBL-SCID) mice with HIV has allowed evaluation of several strategies for preventing or treating infection. In one study, hu-PBL-SCID mice derived from HIV gp160-vaccinated donors were shown to resist HIV infection, and resistance correlated best with in vitro assays of cellular immunity. We have assessed directly the importance of cellular immunity to HIV in the present experiments by the adoptive transfer of HLA-A3-restricted HIV-1 Nef-specific or HLA-B14-restricted Gag-specific CD8+ CTL clones to SCID mice bearing HLA-matched or mismatched PBL grafts. Multiple inoculations of CTL before and after HIV-1 exposure protected HLA-matched hu-PBL-SCID mice from infection, but initiation of CTL therapy on the same day as HIV infection was much less effective. However, at the high numbers of CTL required for complete protection from HIV infection, many HLA-mismatched hu-PBL-SCID mice were also protected by pre-exposure CTL transfer. Transfer of CTL with a different specificity (HTLV-1 Tax) to HLA-matched hu-PBL-SCID mice also afforded partial protection. These results suggest that HLA-restricted cytotoxicity may be less important than other nonspecific effector mechanisms for the inhibition of HIV-1 infection in vivo.

Cultivation of the exoerythrocytic stage of Plasmodium berghei in primary cultures of mouse hepatocytes and continuous mouse cell lines

Plasmodium berghei exoerythrocytic (EE) stages have been cultured in vitro in human continuous cell lines and primary cultures of both human and rat hepatocytes. Although the predominant experimental model of irradiated sporozoite-induced protective immunity is the mouse, P. berghei has not been cultivated in primary mouse hepatocytes or in continuous mouse lines. Because of this, target cells are not available for determining if these immunized mice produce cytotoxic T lymphocytes (CTLs) that recognize P. berghei antigens expressed on hepatocytes in the context of class I major histocompatability (MHC) antigens. We report the development of methods for cultivating the (EE) stage of P. berghei in murine hepatocytes and in two cell lines derived from the livers of BALB/c mice; one line produced from a primary hepatocyte culture and the other produced by fusion of mouse hepatocytes with a continuous rat liver line. Mature parasites were detected by microscopy and by DNA probe in both cell lines, each of which supported complete development of P. berghei liver stages and production of infectious merozoites. Since class I MHC antigens are present on the surface of primary hepatocytes and the mouse X rat hybrid line, these cells can be used to detect cytotoxic T cells against liver stage parasites.