Persistent differences in the level of chimerism in B versus T cells of Freemartin cattle

Immunohematological features of free-living Alouatta belzebul (Linnaeus, 1766) red-handed howler monkeys in the Eastern Amazon

The red-handed howler monkey (Alouatta belzebul) is one of the 35 threatened Brazilian primate species found in two highly endangered Brazilian biomes. Their Amazonian native populations have been declining due to exponential deforestation associated with human activities, especially the construction of dams. The studied population (n = 27) was located in the Belo Monte dam Area of Influence. For the first time, we presented hematological parameters and the basic profile of T (CD3) and B (BSAP PAX5) cells by immunocytochemistry. The results supported the hypothesis that the immuno-hematological profile is influenced by sex, age, and season. Eosinophils were significantly higher in females (p = 0.03), monocytes statistically greater in juveniles (p = 0.04), and total plasma protein increased significantly (p > 0.001) during the dry season. Furthermore, adults showed a statistically higher average absolute number of B lymphocytes than young individuals (p = 0.03), in contrast to T lymphocytes. Even without knowing the full history of antigenic exposure, these results not only contribute to elucidating the boundaries between health and disease but may help lay the groundwork for future research into the effects of anthropogenic stress on immune activation.

Applying real-time quantitative PCR to diagnosis of freemartin in Holstein cattle by quantifying SRY gene: a comparison experiment

BACKGROUND

Freemartinism generally occurs in female offspring of dizygotic twins in a mixed-sex pregnancy. Most bovine heterosexual twin females are freemartins. However, about 10% of bovine heterosexual twin females are fertile. Farmers mostly cull bovine fertile heterosexual twin females due to the lack of a practical diagnostic approach. Culling of such animals results in economic and genetic-material losses both for dairy and beef industry.

METHODS

In this study, a comparative test, including qualitative detection of SRY gene by polymerase chain reaction (PCR), quantitative detection of relative content of SRY by real-time quantitative polymerase chain reaction (qPCR), and quantitative detection of H-Y antigen, was performed to establish the most accurate diagnosis for freemartin. Twelve Holstein heterosexual twin females were used in this study, while three normal Holstein bulls and three normal Holstein cows were used as a positive and negative control, respectively.

RESULTS

Polymerase chain reaction results revealed that SRY gene were absent in three heterosexual twin females and only two of them were verified as fertile in later age. The qPCR results showed that relative content of SRY was more than 14.2% in freemartins and below 0.41% in fertile heterosexual twin females. The H-Y antigen test showed no significant numerical difference between freemartin and fertile heterosexual twin female.

DISCUSSION

Our results show that relative content of SRY quantified by qPCR is a better detection method for diagnosis of freemartin in Holstein cattle as compare to qualitative detection of SRY gene by PCR or quantitative detection of H-Y antigen. To the authors' knowledge, this is the first time we applied qPCR to diagnosing freemartin by quantifying SRY gene and got relative SRY content of each freemartin and fertile heterosexual twin female. We concluded that low-level of SRY would not influence fertility of bovine heterosexual twin female.

Diagnóstico molecular, citogenético y anatomohistopatológico del Síndrome Freemartin en hembras bovinas en Colombia

El síndrome Freemartin es un estado de intersexualidad de muchas de las hembras bovinas provenientes de parto múltiple heterosexual (macho – hembra). Éste se origina en la vida fetal entre los 30 y 40 días de gestación producto del intercambio transplacentario de células mediante anastomosis vasculares, presentándose fenómenos de quimerismo 60XX/XY en varios tejidos, y esterilidad consecuente. En el presente trabajo se tomaron 106 muestras de sangre de terneras provenientes de parto múltiple heterosexual, se realizó extracción de ADN de leucocitos y se buscó la amplificación del gen SRY asociado al cromosoma “Y” mediante PCR y lectura en gel de agarosa. 90 terneras (84.9%) de las 106 amplificaron SRY, verificando el quimerismo 60XX/XY, y 16 terneras (15.1%) que no amplificaron el gen, libres del síndrome quimérico y por lo tanto, aptas reproductivamente. El análisis citogenético realizado mediante cultivo de linfocitos demostró la presencia del cromosoma “Y” en linfocitos de hembras positivas a SRY y la ausencia del quimerismo en hembras SRY negativas.  El análisis anatómico post mortem de tractos reproductivos de hembras positivas a SRY detectó anormalidades características del síndrome tales como, clítoris hipertrofiados y atresias ductales cervicales.  El análisis histopatológico de placas de gónadas de estos animales evidenció la presencia de ovotestículos. El presente estudio confirma la utilidad de las técnicas de biología molecular como herramientas diagnósticas del síndrome, para el aprovechamiento de hembras de reemplazo al servicio del hato bovino.Palabras clave: cariotipo, genotipificación, intersexualidad, quimerismo, SRY.

Activation-induced cytidine deaminase (AID) is strongly expressed in the fetal bovine ileal Peyer's patch and spleen and is associated with expansion of the primary antibody repertoire in the absence of exogenous antigens

Due to a limited range of immunoglobulin (Ig) genes, cattle and several other domestic animals rely on postrecombinatorial amplification of the primary repertoire. We report that activation-induced cytidine deaminase (AID) is strongly expressed in the fetal bovine ileal Peyer's patch and spleen but not in fetal bone marrow. The numbers of IGHV (immunoglobulin heavy chain variable) mutations correlate with AID expression. The mutational profile in the fetuses is similar to postnatal and immunized calves, with targeting of complementarity-determining region (CDR) over framework region (FR), preference of replacement over silent mutations in CDRs but not in FRs, and targeting of the AID hotspot motif RGYW/WRCY. Statistical analysis indicates negative selection on FRs and positive selection on CDRs. Our results suggest that AID-mediated somatic hypermutation and selection take place in bovine fetuses, implying a role for AID in the diversification of the primary antibody repertoire in the absence of exogenous antigens.

Expressional analysis of immunoglobulin D in cattle (Bos taurus), a large domesticated ungulate

For decades, it has remained unknown whether artiodactyls, such as cattle, pigs, and sheep, express immunoglobulin D (IgD), although the δ gene was identified in these species nearly 10 years ago. By developing a mouse anti-bovine IgD heavy chain monoclonal antibody (13C2), we show that secreted bovine IgD was present mainly as a monomer in serum and was heavily glycosylated by N-linked saccharides. Nonetheless, IgD was detectable in some but not all of the Holstein cattle examined. Membrane-bound IgD was detected in the spleen by western blotting. Flow cytometric analysis demonstrated that IgD-positive B cells constituted a much lower percentage of B cells in the bovine spleen (∼6.8% of total B cells), jejunal Peyer's patches (∼0.8%), and peripheral blood leukocytes (∼1.2%) than in humans and mice. Furthermore, IgD-positive B cells were almost undetectable in bovine bone marrow and ileal Peyer's patches. We also demonstrated that the bovine δ gene can be expressed via class switch recombination. Accordingly, bovine δ germline transcription, which involves an Iδ exon and is highly homologous to Iμ, was confirmed. However, we could not identify an Iδ promoter, despite bovine Eμ demonstrating both enhancer and promoter activity. This study has answered a long-standing question in cattle B cell biology and significantly contributes to our understanding of B cell development in this species.

B lymphopoiesis is characterized by pre-B cell marker gene expression in fetal cattle and declines in adults

Fetal cattle B-cell development proceeds via a pre-B cell stage that is characterized by the expression of surrogate light chain and recombination activation genes. In this paper, we identify a new member of bovine pre-B lymphocyte genes, VPREB2. Using RT-qPCR, we assess the expression of VPREB2 and three other surrogate light chain genes as well as RAG1 and RAG2 in fetal and adult cattle tissues. The absence of VPREB1, IGLL1, RAG1 and RAG2 expression in adult tissues and the lack of B-lymphoid differentiation in adult bone marrow - OP9 stromal cell co-culture, suggest a decline of B lymphopoiesis in adult cattle. The marked differences in the expression profiles of VPREB2 and VPREB3 in comparison to those of VPREB1, IGLL1 and RAGs suggest that the biological roles of VPREB2 and VPREB3 are unrelated to the pre-B cells.

Direct observation of hematopoietic progenitor chimerism in fetal freemartin cattle

Background

Cattle twins are well known as blood chimeras. However, chimerism in the actual hematopoietic progenitor compartment has not been directly investigated. Here, we analyzed fetal liver of chimeric freemartin cattle by combining a new anti-bovine CD34 antibody and Y-chromosome specific in situ hybridization.

Results

Bull-derived CD34⁺ cells were detected in the liver of the female sibling (freemartin) at 60 days gestation. The level of bull-derived CD34⁺ cells was lower in the freemartin than in its male siblings. Bull (Y⁺) and cow hematopoietic cells often occurred in separate clusters. Around clusters of Y⁺CD34⁺ cells, Y⁺CD34^- cells were typically observed. The thymi were also strongly chimeric at 60 days of gestation.

Conclusion

The fetal freemartin liver contains clusters of bull-derived hematopoietic progenitors, suggesting clonal expansion and differentiation. Even the roots of the hematopoietic system in cattle twins are thus strongly chimeric from the early stages of fetal development. However, the hematopoietic seeding of fetal liver apparently started already before the onset of functional vascular anastomosis.

The bovine antibody repertoire

Cattle are able to produce a full range of Ig classes including the long-elusive IgD through rearrangement of their germline genes. Several IgL groupings have been reported but as in several other livestock species (e.g. sheep, rabbits, chickens), rearrangement per se fails to generate significant IgH diversity. This is largely because of the modest number of bovine VH segments that participate in rearrangement and their conserved sequences. Perhaps in compensation, bovine Ig heavy chains carry CDR3 sequences of exceptional length. Processes that operate post-rearrangement to generate diversity remain ill defined as are the location, timing and triggers to these events. Reagents are needed to understand better the maturation of B lymphocytes, their responses to antigens and cytokines, and to provide standards for the quantitation of Ig responses in cattle; recombinant methods may help meet this need as Ab engineering technologies become more widely used.

The freemartin syndrome: an update

The freemartin condition represents the most frequent form of intersexuality found in cattle, and occasionally other species. This review considers the current state of knowledge of freemartin biology, incidence, experimental models, diagnosis, uses for freemartins in cattle herds, occurrence in non-bovine species, effects on the male, and highlights potential new research areas. Freemartins arise when vascular connections form between the placentae of developing heterosexual twin foeti, XX/XY chimerism develops, and ultimately there is masculinisation of the female tubular reproductive tract to varying degrees. With twinning rates in Holstein cows increasing, there will be greater economic importance to establish early diagnosis of the freemartin and the detection of the less common single born freemartin. New diagnostic methods based on the detection of Y-chromosome DNA segments by polymerase chain reaction (PCR) show improved assay sensitivity and efficiency over karyotyping and clinical examination. The implications for the chimeric male animal born co-twin to the freemartin are contentious as to whether fertility is affected; if germ cell chimerism does indeed occur; and, if there are any real effects on the sex ratio of offspring produced. In beef cattle, the freemartin carcass has similar characteristics to normal herdmates. Hormonal treatment of freemartins for use as oestrous detectors has been used to obtain salvage value. The biology of freemartin sheep has recently been studied in detail, and the condition may be increasing in prevalence with the introduction of high fecundity genes into flocks. Potential new research areas are discussed, such as detection of foetal DNA in maternal circulation for prenatal diagnosis and investigation of the anti-tumour properties of Mullerian inhibiting substance (MIS). The freemartin syndrome will always be a limiting factor in cattle and to a lesser extent in sheep production systems that have the goal to produce multiple reproductively normal female offspring from a single dam without using sex predetermination.

Maternal-Fetal Transplacental Leakage of Mitochondrial DNA in Bovine Nuclear Transfer Pregnancies: Potential Implications for Offspring and Recipients

The synepitheliochorial placenta of ruminants is constructed of multiple tissue layers that separate maternal and fetal blood. In nuclear transfer cloned ruminants, however, placental anomalies such as abnormal vascular development and hemorrhagic cotyledons have been reported. We have investigated the possible exchange of genetic material between somatic cell nuclear transfer cloned (SCNT) bovine fetuses and recipients at day 80 of gestation using mitochondrial DNA (mtDNA) as a marker. Twenty-three recovered SCNT-fetuses and their recipients were screened for divergent and thus informative mtDNA combinations. Twenty-one fetuses generated by in vitro fertilization (IVF) or multiple ovulation embryo transfer (MOET) and the corresponding recipients served as controls. A search for recipient mtDNA haplotype in DNA extracts from fetal blood by PCR-RFLP analysis revealed three cases of chimerism (two SCNT, one IVF) among a total of 19 informative fetus-recipient pairs (eight SCNT, seven IVF, four MOET). Placental anomalies have also been observed in some IVF fetuses and the present data therefore suggests transplacental leakage of cell components or cells from the recipient into some fetuses generated by in vitro techniques. Further studies are necessary to determine (i) the nature of leaked material, (ii) whether there is bi-directional leakage, and (iii) whether leaked material is present in recipients and calves after parturition, i.e. whether leakage takes place in vivo. If recipients were chimeric for DNA or cells derived from genetically modified SCNT (or IVF) embryos, their subsequent utilization might be affected.

Limited Contribution of Circulating Cells to the Development and Maintenance of Nonhematopoietic Bovine Tissues

Bone marrow-derived stem cells appear surprisingly multipotent in experimental settings, but the physiological significance of such plasticity is unclear. We have used sex-mismatched cattle twins with stably chimeric hematopoietic systems to investigate the general extent of integration of circulating cells to the nonhematopoietic cell lineages in an unmanipulated large mammal. The donor-derived (Y+) nonhematopoietic cells in female recipient tissues were visualized by Y-chromosome specific in situ hybridization combined with pan-leukocyte labeling. Y+ leukocytes were frequent in all tissues, but in 11 of 12 animals, average contribution to nonhematopoietic lineages was in any tissue below 1% (in brain <0.001%). Significantly higher integration rate was detected in regenerating granulation tissue. Also, one animal showed a high frequency of nonhematopoietic Y+ cells in several tissues, including intestinal epithelium and mammary gland stroma. In conclusion, circulating cells do not appear significant in the development and maintenance of nonhematopoietic bovine tissues, but may be important in regeneration and other special conditions.