Visualizing sexual dimorphism in the brain

Sexually dimorphic behaviors are likely to involve neural pathways that express the androgen receptor (AR). We have genetically modified the AR locus to visualize dimorphisms in neuronal populations that express AR. Analysis of AR-positive neurons reveals both known dimorphisms in the preoptic area of the hypothalamus and the bed nucleus of the stria terminalis as well as novel dimorphic islands in the basal forebrain with a clarity unencumbered by the vast population of AR-negative neurons. This genetic approach allows the visualization of dimorphic subpopulations of AR-positive neurons along with their projections and may ultimately permit an association between neural circuits and specific dimorphic behaviors.     

Spontaneous neural activity is required for the establishment and maintenance of the olfactory sensory map

We have developed a genetic approach to examine the role of spontaneous activity and synaptic release in the establishment and maintenance of an olfactory sensory map. Conditional expression of tetanus toxin light chain, a molecule that inhibits synaptic release, does not perturb targeting during development, but neurons that express this molecule in a competitive environment fail to maintain appropriate synaptic connections and disappear. Overexpression of the inward rectifying potassium channel, Kir2.1, diminishes the excitability of sensory neurons and more severely disrupts the formation of an olfactory map. These studies suggest that spontaneous neural activity is required for the establishment and maintenance of the precise connectivity inherent in an olfactory sensory map.     

A combined treatment with 1alpha,25-dihydroxy-vitamin D3 and 17beta-estradiol reduces the expression of heat shock protein-32 (HSP-32) following cerebral cortical ischemia

1alpha,25-(OH)(2)-vitamin D(3) (1,25-D(3)) and 17beta-estradiol are both known to act neuroprotectively in certain experimental in vitro and in vivo settings and it has been noted that both steroids lead to an upregulation of certain neurotrophic factors. Here, we studied the effects of 1alpha,25-(OH)(2)-vitamin D(3) or 17beta-estradiol or their combined application on heat shock protein-32 (HSP-32) distribution after focal cortical ischemia using the well established photothrombosis model. Heat shock protein-32 is a well-established marker of the cerebral oxidative stress response and contributes to neuroprotection by metabolising cytotoxic free heme to carbon monoxide, iron and biliverdin. Photothrombotically lesioned rats were injected i.p. 1h after injury with either 1 microg 1alpha,25-(OH)(2)-vitamin D(3)/kg or 7 microg 17beta-estradiol/kg or a combination of both steroids. Groups of non-lesioned steroid-treated rats and lesioned, solvent-treated rats served as controls. In contrast to non-lesioned rats, in lesioned animals a significant increase in heat shock protein-32 expression occurred which was slightly, but non-significantly altered in the groups treated either with 1alpha,25-(OH)(2)-vitamin D(3) or 17beta-estradiol alone when compared to the solvent-treated control group. Only the combined treatment with 1alpha,25-(OH)(2)-vitamin D(3) and 17beta-estradiol resulted in a significant reduction of glial heat shock protein-32 immunoreactivity within the lesion-remote cortical areas supplied by the affected middle cerebral artery (MCA), indicating that both steroids act synergistically in a protective manner.     

Marsupial relationships and a timeline for marsupial radiation in South Gondwana

Recent marsupials include about 280 species divided into 18 families and seven orders. Approximately 200 species live in Australia/New Guinea. The remaining species inhabit South America with some of these secondarily ranging into North America. In this study, we examine marsupial relationships and estimate their divergences times using complete mitochondrial (mt) genomes. The sampling, which includes nine new mtDNAs and a total number of 19 marsupial genomes, encompasses all extant orders and 14 families. The analysis identified a basal split between Didelphimorphia and remaining orders about 69 million years before present (MYBP), while other ordinal divergences were placed in Tertiary times. The monotypic South American order Microbiotheria (Dromiciops gliroides, Monito del Monte) was solidly nested among its Australian counterparts. The results suggest that marsupials colonized Australia twice from Antarctica/South America and that the divergence between Microbiotheria and its Australian relatives coincided with the geological separation of Antarctica and Australia. Within Australia itself, several of the deepest divergences were estimated to have taken place close to the Eocene/Oligocene transition.     

Plasmid-mediated florfenicol and ceftriaxone resistance encoded by the floR and bla(CMY-2) genes in Salmonella enterica serovars Typhimurium and Newport isolated in the United States

Multidrug resistance plasmids carrying the bla(CMY-2) gene have been identified in Salmonella enterica serovars Typhimurium and Newport from the United States. This gene confers decreased susceptibility to ceftriaxone, and is most often found in strains with concomitant resistance to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole and tetracycline. The bla(CMY-2)-carrying plasmids studied here were shown to also carry the florfenicol resistance gene, floR, on a genetic structure previously identified in Escherichia coli plasmids in Europe. These data indicate that the use of different antimicrobial agents, including phenicols, may serve to maintain multidrug resistance plasmids on which extended-spectrum cephalosporin resistance determinants co-exist with other resistance genes in Salmonella.     

Role of an acrR mutation in multidrug resistance of in vitro-selected fluoroquinolone-resistant mutants of Salmonella enterica serovar Typhimurium

Quinolone resistance in Salmonella spp. is usually attributed to both active efflux and mutations leading to modification of the target enzymes DNA gyrase and topoisomerase IV. Here, we investigated the presence of mutations in the efflux regulatory genes of fluoroquinolone- and multidrug-resistant mutants of Salmonella enterica serovar Typhimurium (S. Typhimurium) selected in vitro with enrofloxacin that both carried a mutation in the target gene gyrA and overproduced the AcrAB efflux pump. No mutations were detected in the global regulatory loci marRAB and soxRS for the four strains studied. A mutation in acrR, the local repressor of acrAB, was found for two ciprofloxacin-resistant selected-mutants, leading to duplication of amino acids Ile75 and Glu76. Complementation experiments with wild-type acrR showed that the mutation identified in acrR partially contributed to the increase in resistance levels to several unrelated antibiotics. The acrR mutation also contributed to acrAB overexpression as shown by RT-PCR. Thus, this study underlines the role of an acrR mutation, in addition to the mutation in gyrA, in the fluoroquinolone and multidrug resistance phenotype of S. Typhimurium mutants, through overexpression of acrAB.     

Towards a simple logic in the determination of biological groups: the species and supraspecific groups

In this paper we discuss about the utility of the species concept as real definition, particularly the Mayr concept. We propose a method for the logical separation of taxa based in the statements of the logical mathematics and the application of the sets theory to the concepts in systematic. We attempt to provide an objective methodology for the interpretation of natural groups in biology including the species as a basic group in evolution. We introduce the concept of the hypothetical ancestor as a mathematical possibility derived from the use of matrix calculations for non square matrix.     

A phylogeny of howler monkeys (Cebidae: Alouatta) based on mitochondrial, chromosomal and morphological data

The current taxonomic status of the species and subspecies belonging to the genus Alouatta is addressed by combined phylogenetic analysis using morphological, kariotipyc and molecular data (mitochondrial genes cytocrome oxidase II and cytochrome B). Our result demonstrated that Alouatta palliata is the most basal taxon for the genus in concordance with previous studies, as well as showing the validity of the taxon Alouatta sara as a species. Also our analysis shows that the sex chromosome has evolved from a XY/XX system to a X1X2Y1Y2/X1X1X2X2 system within the genus, as well as an increase in the size and complexity of the hioideal bone.     

Ultrasonographic characterization of the ovaries and the uterus in prepubertal and pubertal gilts

In two experiments (EXP), 44 and 52 crossbred gilts (mean age+/-S.D. and weight+/-S.D.: 204+/-22 and 203+/-9 days, 114+/-13 and 127+/-12 kg, respectively, in EXP 1 and 2) from four farms were examined by means of transcutaneous ultrasonography (US) to define the characteristics of the ovaries and the uterus (echotexture, size) and to investigate the appropriateness of US to determine sexual maturity. Gilts were judged as prepubertal [PRE; follicles 2-5 mm (F2-5) only] or pubertal [PUB; F7-8, corpora lutea (CL), corpora haemorrhagica (CH)] at the first (PUB-1; EXP 1) or a subsequent estrous cycle [PUB-2; additionally corpora albicantia (CA); EXP 1] by US, and results were verified by postmortem examination (EXP 1), or progesterone analysis and detection of estrous signs (EXP 2). Accuracy of US was 100% for PRE and PUB (both EXP) and 77.3% for PUB-1 and PUB-2 (EXP 1). PRE and PUB with CL/CH had uteri of homogeneous, PUB with F7-8 of heterogeneous echotexture. The size was expressed as the mean sectional area (SAsono) of 2-5 cross-sections of the uterine horns (calculated by multiplication of 1/2 the maximum x the minimum dimension of the cross-sections x pi). SAsono corresponded with the sectional area of postmortem dissected transverse uterine segments relatively with r=0.92 (P<0.0001; EXP 1). Mean SAsono (both EXP) and mean uterine weight (EXP 1) were PRE相似文献   

Expression, Isolation, and Crystallization of the Catalytic Domain of CopB, a Putative Copper Transporting ATPase from the Thermoacidophilic Archaeon Sulfolobus solfataricus

The P-type CPX-ATPases are responsible for the transport of heavy metal ions in archaea, bacteria, and eukaryotes. We have chosen one of the two CPX-ATPases of the thermophile Sulfolobus solfataricus, CopB (= SSO2896) for the investigation of the molecular mechanism of this integral membrane protein. We recombinately expressed three different soluble domains of this protein (named CopB-A, CopB-B, and CopB-C) in Escherichia coli and purified them to homogeneity. 3D crystals of CopB-B, the 29 kDa catalytic ATP binding/phosphorylation domain were produced, which diffracted to a resolution of 2.2 A. CopB-B has heavy metal stimulated phosphatase activity, which was half maximal in the presence of 80 microM Cu2+. The protein forms a phosphorylated intermediate with the substrate gamma-(32P)-ATP. No specific activation of the polypeptide was observed, when CopB-B phosphatase activity was tested in the presence of the purified CopB-C and CopB-A proteins, which provide the cation binding and the phosphatase domains. We conclude that CopB is a putatively copper translocating ATPase, in which structural elements integrally located in the membrane are required for full, coordinated activation of the catalytic ATP binding domain.