Biochemical differentiation in bile duct cestodes and their marsupial hosts

Isozyme electrophoresis was used to assess possible cospeciation of parasites (cestodes of the Progamotaenia festiva complex) and their hosts (Australian diprotodont marsupials) and to compare the extent of interspecific genetic diversity of the parasites and their hosts. On the basis of morphology, there are three species in the complex, although electrophoresis revealed 14 distinct genetic types, most of which were host specific, although there were three cases of apparent host switching. The evolutionary relationships among the parasites were only partially concordant with those among the hosts. Moreover, the extent of electrophoretic diversity among the parasites was much higher than that among hosts.      

The angiogenic response is dictated by β3 integrin on bone marrow–derived cells

Angiogenesis is dependent on the coordinated action of numerous cell types. A key adhesion molecule expressed by these cells is the α_vβ₃ integrin. Here, we show that although this receptor is present on most vascular and blood cells, the key regulatory function in tumor and wound angiogenesis is performed by β₃ integrin on bone marrow–derived cells (BMDCs) recruited to sites of neovascularization. Using knockin mice expressing functionally stunted β₃ integrin, we show that bone marrow transplantation rescues impaired angiogenesis in these mice by normalizing BMDC recruitment. We demonstrate that α_vβ₃ integrin enhances BMDC recruitment and retention at angiogenic sites by mediating cellular adhesion and transmigration of BMDCs through the endothelial monolayer but not their release from the bone niche. Thus, β₃ integrin has the potential to control processes such as tumor growth and wound healing by regulating BMDC recruitment to sites undergoing pathological and adaptive angiogenesis.     

Expression of membrane associated non-genomic progesterone receptor(s) in caprine spermatozoa

Mammalian spermatozoa have been used recently to model the study of rapid, non-genomic effects of progesterone on cell. Our study used progesterone-BSA-fluorescein isothiocyanate conjugate to indicate the presence of a progesterone receptor on the surface of >90% of a goat sperm population. The sperm possessed the receptor at 0 h and capacitation had no modulating effect on the number of sperm responsive to P-BSA-FITC. Although a decrease in receptor bearing cells was observed during the course of capacitation, the effect may have been due to the induction of acrosome reaction (AR) by the conjugate. This decrease was blocked by the pre-treatment of the spermatozoa with EGTA. Binding of conjugate occurred at the apical portion of the acrosome and at the post-acrosomal region in all the sperm, possibly mediating sperm functions other than the acrosome reaction. The P-BSA-FITC treated cells showed a single peak in a flow cytometer suggesting that the sperm population was homogeneous. Competition studies with free progesterone and GABA with P-BSA-FITC confirmed that the binding was specific and that progesterone mediated its action via a GABA(A)/Cl(-) channel complex akin to the one present in neuronal cells.     

Analysis of genes of mitochondrial origin in the genus Entamoeba

The amitochondriate protistan parasite Entamoeba histolytica has lost most mitochondrial functions secondarily but has retained a reduced organelle of mitochondrial origin, the mitosome. We here investigate the presence, origins, and expression in other species of Entamoeba of three genes of mitochondrial origin--pyridine nucleotide transhydrogenase and the mitochondrial-type chaperonins cpn60 and hsp70. The genes appear to be present in all species and specifically related, confirming that the E. histolytica mitosomal genes were not acquired recently by lateral transfer from another organism. Detection of expression was not possible in all cases under the culture conditions used, but several genes were induced during recovery from exposure to a heat shock. This includes the transhydrogenase, which to our knowledge has not been shown previously to be a heat-shock protein.