Indigenous domestic breeds as reservoirs of genetic diversity: the Argentinean Creole cattle

Contrary to highly selected commercial breeds, indigenous domestic breeds are composed of semi-wild or feral populations subjected to reduced levels of artificial selection. As a consequence, many of these breeds have become locally adapted to a wide range of environments, showing high levels of phenotypic variability and increased fitness under natural conditions. Genetic analyses of three loci associated with milk production (alpha(S1)-casein, kappa-casein and prolactin) and the locus BoLA-DRB3 of the major histocompatibility complex indicated that the Argentinean Creole cattle (ACC), an indigenous breed from South America, maintains high levels of genetic diversity and population structure. In contrast to the commercial Holstein breed, the ACC showed considerable variation in heterozygosity (H(e)) and allelic diversity (A) across populations. As expected, bi-allelic markers showed extensive variation in He whereas the highly polymorphic BoLA-DRB3 showed substantial variation in A, with individual populations having 39-74% of the total number of alleles characterized for the breed. An analysis of molecular variance (AMOVA) of nine populations throughout the distribution range of the ACC revealed that 91.9-94.7% of the total observed variance was explained by differences within populations whereas 5.3-8.1% was the result of differences among populations. In addition, the ACC breed consistently showed higher levels of genetic differentiation among populations than Holstein. Results from this study emphasize the importance of population genetic structure within domestic breeds as an essential component of genetic diversity and suggest that indigenous breeds may be considered important reservoirs of genetic diversity for commercial domestic species.     

Poliovirus morphogenesis. I. Identification of 80S dissociable particles and evidence for the artifactual production of procapsids.

The current model of poliovirus morphogenesis postulates a fundamental role for procapsid, 80S shells that, upon interaction with viral RNA and subsequent proteolytic cleavage, give rise to complete virus particles. Although 80S sedimenting particles can, indeed, be isolated from cytoplasmic extracts of infected cells, their physical properties differ from those reported for procapsids. Far from being stable structures, they can be dissociated by pH 8.5 and 0.1% sodium dodecyl sulfate into slower-sedimenting subunits. The reasons for this discrepancy were investigated, and two main modalities leading to the appearance of procapsids in vitro were identified. The first involves a temperature-mediated conversion of dissociable 80S particles into stable 80S procapsids, and the second involves the self-assembly of endogenous 14S subunits, also primed by an increase in the temperature of cytoplasmic extracts.     

Proposed megakaryocytic regulon of p53: the genes engaged to control cell cycle and apoptosis during megakaryocytic differentiation

During endomitosis, megakaryocytes undergo several rounds of DNA synthesis without division leading to polyploidization. In primary megakaryocytes and in the megakaryocytic cell line CHRF, loss or knock-down of p53 enhances cell cycling and inhibits apoptosis, leading to increased polyploidization. To support the hypothesis that p53 suppresses megakaryocytic polyploidization, we show that stable expression of wild-type p53 in K562 cells (a p53-null cell line) attenuates the cells' ability to undergo polyploidization during megakaryocytic differentiation due to diminished DNA synthesis and greater apoptosis. This suggested that p53's effects during megakaryopoiesis are mediated through cell cycle- and apoptosis-related target genes, possibly by arresting DNA synthesis and promoting apoptosis. To identify candidate genes through which p53 mediates these effects, gene expression was compared between p53 knock-down (p53-KD) and control CHRF cells induced to undergo terminal megakaryocytic differentiation using microarray analysis. Among substantially downregulated p53 targets in p53-KD megakaryocytes were cell cycle regulators CDKN1A (p21) and PLK2, proapoptotic FAS, TNFRSF10B, CASP8, NOTCH1, TP53INP1, TP53I3, DRAM1, ZMAT3 and PHLDA3, DNA-damage-related RRM2B and SESN1, and actin component ACTA2, while antiapoptotic CKS1B, BCL2, GTSE1, and p53 family member TP63 were upregulated in p53-KD cells. Additionally, a number of cell cycle-related, proapoptotic, and cytoskeleton-related genes with known functions in megakaryocytes but not known to carry p53-responsive elements were differentially expressed between p53-KD and control CHRF cells. Our data support a model whereby p53 expression during megakaryopoiesis serves to control polyploidization and the transition from endomitosis to apoptosis by impeding cell cycling and promoting apoptosis. Furthermore, we identify a putative p53 regulon that is proposed to orchestrate these effects.     

Genetic diversity and differentiation of guanaco populations from Argentina inferred from microsatellite data

Genotype data from 14 microsatellite markers were used to assess the genetic diversity and differentiation of four guanaco populations from Argentine Patagonia. These animals were recently captured in the wild and maintained in semi-captivity for fibre production. Considerable genetic diversity in these populations was suggested by the finding of a total of 162 alleles, an average mean number of alleles per locus ranging from 6.50 to 8.19, and H(e) values ranging from 0.66 to 0.74. Assessment of population differentiation showed moderate but significant values of F(ST)=0.071 (P=0.000) and R(ST)=0.083 (P=0.000). An amova test showed that the genetic variation among populations was 5.6% while within populations it was 94.4%. A number of 6.6 migrants per generation may support these results. Unambiguous individual assignment to original populations was obtained for the Pilcaniyeu, Las Heras and La Esperanza populations. The erroneous assignment of 18.75% Rio Mayo individuals to the Las Heras population can be explained by the low genetic differentiation found between these two populations. Thirty-nine of 56 loci per population combinations were in Hardy--Weinberg disequilibrium because of guanaco heterozygote deficiency, which may be explained by population subdivision. The high level of genetic diversity of the guanacos analysed here indicates that the Patagonian guanaco constitutes an important genetic resource for conservation or economic utilization programmes.     

Molecular genetic diversity within Myrmeleontidae family

Antlions are insects which feed on ants, insect which dig a pit and lies in wait for ants and other insects. Twelve species of Myrmeleontidae family as antlions and many specimens were identified in different locations in Fars province in Iran. To unveil the genetic similarity between these species, their DNA was extracted by modified CTAB method and with the use of seventeen 10-nucleotides primers of random amplified polymorphic DNA (RAPD); the genetic analysis of them was investigated. After PCR, agarose 1.5?% was used for electrophoresis. The obtained electrophoresis bands had base pairs range between 150 and 1,000?bp. The maximum of polymorphic bands belonged to OPH5, N13, and the minimum of polymorphic bands belonged to OPA7 primers. Different genetic similarity indices were found between eight species of antlions. Possibility of use of RAPD marker together with morphological studies for classification and identification of antlions is discussed.     

Lipid rafts/caveolae as microdomains of calcium signaling

Ca²⁺ is a major signaling molecule in both excitable and non-excitable cells, where it serves critical functions ranging from cell growth to differentiation to cell death. The physiological functions of these cells are tightly regulated in response to changes in cytosolic Ca²⁺ that is achieved by the activation of several plasma membrane (PM) Ca²⁺ channels as well as release of Ca²⁺ from the internal stores. One such channel is referred to as store-operated Ca²⁺ channel that is activated by the release of endoplasmic reticulum (ER) Ca²⁺ which initiates store-operated Ca²⁺ entry (SOCE). Recent advances in the field suggest that some members of TRPCs and Orai channels function as SOCE channels. However, the molecular mechanisms that regulate channel activity and the exact nature of where these channels are assembled and regulated remain elusive. Research from several laboratories has demonstrated that key proteins involved in Ca²⁺ signaling are localized in discrete PM lipid rafts/caveolar microdomains. Lipid rafts are cholesterol and sphingolipid-enriched microdomains that function as unique signal transduction platforms. In addition lipid rafts are dynamic in nature which tends to scaffold certain signaling molecules while excluding others. By such spatial segregation, lipid rafts not only provide a favorable environment for intra-molecular cross-talk but also aid to expedite the signal relay. Importantly, Ca²⁺ signaling is shown to initiate from these lipid raft microdomains. Clustering of Ca²⁺ channels and their regulators in such microdomains can provide an exquisite spatiotemporal regulation of Ca²⁺-mediated cellular function. Thus in this review we discuss PM lipid rafts and caveolae as Ca²⁺-signaling microdomains and highlight their importance in organizing and regulating SOCE channels.