Species-wide distribution of highly polymorphic minisatellite markers suggests past and present genetic exchanges among house mouse subspecies

Background  

Four hypervariable minisatellite loci were scored on a panel of 116 individuals of various geographical origins representing a large part of the diversity present in house mouse subspecies. Internal structures of alleles were determined by minisatellite variant repeat mapping PCR to produce maps of intermingled patterns of variant repeats along the repeat array. To reconstruct the genealogy of these arrays of variable length, the specifically designed software MS_Align was used to estimate molecular divergences, graphically represented as neighbor-joining trees.     

Immunological similarities between specific chloroplast ribosomal proteins from Chlamydomonas reinhardtii and ribosomal proteins from Escherichia coli

Polyclonal antibodies were elicited against seven of the 33 different proteins of the large subunit of the chloroplast ribosome from Chlamydomonas reinhardtii. Three of these proteins are synthesized in the chloroplast and four are made in the cytoplasm and imported. In western blots, six of the seven antisera are monospecific for their respective large subunit ribosomal proteins, and none of these antisera cross-reacted with any chloroplast small subunit proteins from C. reinhardtii. Antisera to the three chloroplast-synthesized ribosomal proteins cross-reacted with specific Escherichia coli large subunit proteins of comparable charge and molecular weight. Only one of the four antisera to the chloroplast ribosomal proteins synthesized in the cytoplasm cross-reacted with an E. coli large subunit protein. None of the antisera cross-reacted with any E. coli small subunit proteins. On the assumption of a procaryotic, endosymbiotic origin for the chloroplast, those chloroplast ribosomal proteins still synthesized within the organelle appear to have retained more antigenic sites in common with E. coli ribosomal proteins than have those which are now the products of cytoplasmic protein synthesis. Antisera to this cytoplasmically synthesized group of chloroplast ribosomal proteins did not recognize any antigenic sites among C. reinhardtii cytoplasmic ribosomal proteins, suggesting that the genes for the cytoplasmically synthesized chloroplast ribosomal proteins either are not derived from the cytoplasmic ribosomal protein genes or have evolved to a point where no antigenic similarities remain.      

Tyrosine phosphorylation of myosin heavy chain during skeletal muscle differentiation: an integrated bioinformatics approach

Previously it has been shown that insulin-mediated tyrosine phosphorylation of myosin heavy chain is concomitant with enhanced association of C-terminal SRC kinase during skeletal muscle differentiation. We sought to identify putative site(s) for this phosphorylation event. A combined bioinformatics approach of motif prediction and evolutionary and structural analyses identified tyrosines163 and 1856 of the skeletal muscle heavy chain as the leading candidate for the sites of insulin-mediated tyrosine phosphorylation. Our work is suggestive that tyrosine phosphorylation of myosin heavy chain, whether in skeletal muscle or in platelets, is a significant event that may initiate cytoskeletal reorganization of muscle cells and platelets. Our studies provide a good starting point for further functional analysis of MHC phosphor-signalling events within different cells.     

An improved method using densitometry for evaluating severity of laser photocoagulation induced CNV

Laser photocoagulation induced choroidal neovascularization currently is the most effective model available for the study of this disease in terms of efficacy of new drugs and therapies. Previously, evaluating the extent of choroidal neovascularization using this model was time- consuming and required the use of experienced personnel. We describe a new method for simple and rapid evaluation of laser induced choroidal neovascularization using densitometry. Fluorescein angiograms of a laser photocoagulated rat eye were scanned into a computer. Densitometry software subsequently was used to calculate the severity of the laser lesions. The densitometry method proved effective for calculating the extent of laser induced choroidal neovascularization. In addition, this method was more rapid than visual evaluations and less likely to produce errors.     

Distribution of MT1 Melatonin Receptor Promoter-Driven RFP Expression in the Brains of BAC C3H/HeN Transgenic Mice

The pineal hormone melatonin activates two G-protein coupled receptors (MT₁ and MT₂) to regulate in part biological functions. The MT₁ and MT₂ melatonin receptors are heterogeneously distributed in the mammalian brain including humans. In the mouse, only a few reports have assessed the expression of the MT₁ melatonin receptor expression using 2-iodomelatonin binding, in situ hybridization and/or polymerase chain reaction (PCR). Here, we described a transgenic mouse in which red fluorescence protein (RFP) is expressed under the control of the endogenous MT₁ promoter, by inserting RFP cDNA at the start codon of MTNR1a gene within a bacterial artificial chromosome (BAC) and expressing this construct as a transgene. The expression of RFP in the brain of this mouse was examined either directly under a fluorescent microscope or immunohistochemically using an antibody against RFP (RFP-MT₁). RFP-MT₁ expression was observed in many brain regions including the subcommissural organ, parts of the ependyma lining the lateral and third ventricles, the aqueduct, the hippocampus, the cerebellum, the pars tuberalis, the habenula and the habenula commissure. This RFP-MT₁ transgenic model provides a unique tool for studying the distribution of the MT₁ receptor in the brain of mice, its cell-specific expression and its function in vivo.     

Evolution of body shape in sympatric versus non-sympatric Tropheus populations of Lake Tanganyika

Allopatric speciation often yields ecologically equivalent sister species, so that their secondary admixis enforces competition. The shores of Lake Tanganyika harbor about 120 distinct populations of the cichlid genus Tropheus, but only some are sympatric. When alone, Tropheus occupies a relatively broad depth zone, but in sympatry, fish segregate by depth. To assess the effects of competition, we studied the partial co-occurrence of Tropheus moorii ‘Kaiser'' and ‘Kirschfleck'' with Tropheus polli. A previous study demonstrated via standardized breeding experiments that some observed differences between Tropheus ‘Kaiser'' living alone and in sympatry with T. polli have a genetic basis despite large-scale phenotypic plasticity. Using geometric morphometrics and neutral genetic markers, we now investigated whether sympatric populations differ consistently in body shape from populations living alone and if the differences are adaptive. We found significant differences in mean shape between non-sympatric and sympatric populations, whereas all sympatric populations of both color morphs clustered together in shape space. Sympatric populations had a relatively smaller head, smaller eyes and a more anterior insertion of the pectoral fin than non-sympatric populations. Genetically, however, non-sympatric and sympatric ‘Kaiser'' populations clustered together to the exclusion of ‘Kirschfleck''. Genetic distances, but not morphological distances, were correlated with geographic distances. Within- and between-population covariance matrices for T. moorii populations deviated from proportionality. It is thus likely that natural selection acts on both phenotypic plasticity and heritable traits and that both factors contribute to the observed shape differences. The consistency of the pattern in five populations suggests ecological character displacement.