Effect of CRF injected into the median eminence on GH secretion in female rats under different steroid status

To evaluate whether the median eminence (ME) is a site of action of CRF (corticotropin releasing factor) on GH secretion and to determine the possible role of estradiol and progesterone in modifying theses secretion, we injected CRF (0.25, 0.75, 1, and 1.5 nmol of peptide dissolved in 1 μl of water) directly into the ME in three experimental groups of rats: Long-term ovariectomized (OVX); OVX primed by estradiol (OVX±E) and OVX primed by estradiol plus progesterone (OVX±EP). Blood was collected to determine GH (30, 60, 90, and 120 min postinjection) Serum T₃, T₄, and glucose levels were measured in OVX±E rats 30 min postinjection. CRF at all doses studied significantly decreased serum GH levels in the three experimental groups. Serum T₃, T₄, and glucose levels were unchanged after CRF administration. The results suggest that: CRF inhibits “per se” GH secretion, at least in part, by a central action in the ME. The inhibitory effect of CRF on GH is independent of the estrogen/progesterone status of the animal. CRF at ME levels may participate in a variety of stress-related responses, including growth inhibition, through GH suppression.     

Patterns of Root Colonization in Epacridaceous Plants Collected from Different Sites

Root colonization was studied in ten species of the Epacridaceaeat three sites in Victoria by morphological and cross-inoculationexperiments. The sites and genera chosen were Cranbourne [Epacrisimpressa Labill. andLeucopogon ericoides(Smith) R. Br.] andRye [L. parviflorus(Andrews) Lindley] on the Mornington Peninsula,and the Grampians[Astroloma conostephioides(Sond.) Benth.,A.humifusum(Cav.) R. Br.,A pinifolium(R. Br.) Benth,Brachylomadaphnoides(Smith) Benth.,E. impressa, E. impressavar.grandifloraBenth.andStyphelia adscendensR. Br.] in western Victoria. For morphologicalstudies, samples of roots from each species at each site werecleared and stained and examined microscopically. For cross-inoculationstudies, cuttings from each site were struck in potting mediuminoculated with soil from the same and other sites. The ericoidmycorrhizae in the roots of plants found at or grown in Cranbourneand Rye soils were similar. Both were significantly differentfrom the internal hyphae found in the roots of plants foundat or grown in Grampians soils, which were three times largerin diameter and formed dense coils which filled the host celland invaded adjacent epidermal cells. This suggests that morethan one fungus is involved in the relationships, that the MorningtonPeninsula sites had a different fungus from the Grampians siteand that host specificity is low. Vesicular structures werealso found commonly on plants at the Grampians site, in contrastwith other sites. Epacridaceae; root; fungus; mycorrhiza; morphology; inoculation     

The effect of B chromosomes on fitness components inAegilops speltoides Tausch

The effect of B chromosomes (Bs) on various components of vigour and fertility inAegilops speltoides was studied. We designed three types of synthetic populations. In the first type we compared plants from the localities Haifa (which has Bs in nature) and Ashkelon (which has not). Non significant differences were found between the plants from both populations, and between B carriers and non carriers among Haifa individuals. In the second synthetic population we compared 0B, 1B, 2B, 3B and 5B plants from Haifa. We found that vigour variables were not affected by the presence of Bs, while fertility variables were significantly correlated with B number, in such a way that 1B plants produce more grains per plant than any other constitution, while 5Bs produce a remarkable deleterious effect. In the third type of synthetic populations we compared plants with 0B and 1B, 0B and 2B, 0B and 3B, and 0B and 5B. In this case we also found that 1B plants were the most fertile, but the variation of reproductive fitness was higher from plot to plot within the same B class than among B classes. We conclude that the effect of B chromosomes on the fitness variables that we have estimated is close to neutrality in this species. We discuss the relation between the strength of the mechanism of accumulation and the deleterious effects of B chromosomes.     

Influence of pool geometry on the biological efficiency of vertical slot fishways

The characteristics of the flow in vertical slot fishways depend mainly on the specific pool design, i.e., the geometry of the pool. This paper presents the results of a study on sixteen different designs of vertical slot fishways with two different slopes. The flow field is studied using both a physical-scale model and a numerical model which solves the 2D depth-averaged shallow water equations coupled with a k–? turbulence model. Several hydraulic parameters, such as the average velocity in the slot or the water depth, are considered in order to evaluate their biological efficiency. Based on the results, it appears that the length of the pool is the main geometric dimension that affects the flow in the fishway. The numerical and experimental agreement is very satisfactory.     

Mitochondrial DNA sequences are present inside nuclear DNA in rat tissues and increase with age

Mitochondrial DNA (mtDNA) mutations increase with age. However, the number of cells with predominantly mutated mtDNA is small in old animals. Here a new hypothesis is proposed: mtDNA fragments may insert into nuclear DNA contributing to aging and related diseases by alterations in the nucleus. Real-time PCR quantification shows that sequences of cytochrome oxidase III and 16S rRNA from mtDNA are present in highly purified nuclei from liver and brain in young and old rats. The sequences of these insertions revealed that they contain single nucleotide polymorphisms identical to those present in mtDNA of the same animal. Interestingly, the amount of mitochondrial sequences in nuclear DNA increases with age in both tissues. In situ hybridization of mtDNA to nuclear DNA confirms the presence of mtDNA sequences inside nuclear DNA in rat hepatocytes. Bone marrow metaphase cells from both young and old rats show mtDNA at centromeric regions in 20 out of the 2n = 40 chromosomes. Consequently, mitochondria can be a major trigger of aging but the final target could also be the nucleus.     

Ultrasound imaging in an experimental model of fatty liver disease and cirrhosis in rats

Background

Atypical scrapie was first identified in Norwegian sheep in 1998 and has subsequently been identified in many countries. Retrospective studies have identified cases predating the initial identification of this form of scrapie, and epidemiological studies have indicated that it does not conform to the behaviour of an infectious disease, giving rise to the hypothesis that it represents spontaneous disease. However, atypical scrapie isolates have been shown to be infectious experimentally, through intracerebral inoculation in transgenic mice and sheep. The first successful challenge of a sheep with 'field' atypical scrapie from an homologous donor sheep was reported in 2007.

Results

This study demonstrates that atypical scrapie has distinct clinical, pathological and biochemical characteristics which are maintained on transmission and sub-passage, and which are distinct from other strains of transmissible spongiform encephalopathies in the same host genotype.

Conclusions

Atypical scrapie is consistently transmissible within AHQ homozygous sheep, and the disease phenotype is preserved on sub-passage.     

Mapping of citrullinated fibrinogen B-cell epitopes in rheumatoid arthritis by imaging surface plasmon resonance

Introduction  

Rheumatoid arthritis (RA) frequently involves the loss of tolerance to citrullinated antigens, which may play a role in pathogenicity. Citrullinated fibrinogen is commonly found in inflamed synovial tissue and is a frequent target of autoantibodies in RA patients. To obtain insight into the B-cell response to citrullinated fibrinogen in RA, its autoepitopes were systematically mapped using a new methodology.     

Quantification of global transcription patterns in prokaryotes using spotted microarrays

We describe an analysis, applicable to any spotted microarray dataset produced using genomic DNA as a reference, that quantifies prokaryotic levels of mRNA on a genome-wide scale. Applying this to Mycobacterium tuberculosis, we validate the technique, show a correlation between level of expression and biological importance, define the complement of invariant genes and analyze absolute levels of expression by functional class to develop ways of understanding an organism's biology without comparison to another growth condition.     

An annotated catalogue of salivary gland transcripts in the adult female mosquito, Ædes ægypti*

Background

The number of completely sequenced plastid genomes available is growing rapidly. This array of sequences presents new opportunities to perform comParative analyses. In comParative studies, it is often useful to compare across wide phylogenetic spans and, within angiosperms, to include representatives from basally diverging lineages such as the genomes reported here: Nuphar advena (from a basal-most lineage) and Ranunculus macranthus (a basal eudicot). We report these two new plastid genome sequences and make comparisons (within angiosperms, seed plants, or all photosynthetic lineages) to evaluate features such as the status of ycf15 and ycf68 as protein coding genes, the distribution of simple sequence repeats (SSRs) and longer dispersed repeats (SDR), and patterns of nucleotide composition.

Results

The Nuphar [GenBank:NC_008788] and Ranunculus [GenBank:NC_008796] plastid genomes share characteristics of gene content and organization with many other chloroplast genomes. Like other plastid genomes, these genomes are A+T-rich, except for rRNA and tRNA genes. Detailed comparisons of Nuphar with Nymphaea, another Nymphaeaceae, show that more than two-thirds of these genomes exhibit at least 95% sequence identity and that most SSRs are shared. In broader comparisons, SSRs vary among genomes in s of abundance and length and most contain repeat motifs based on A and T nucleotides.

Conclusion

SSR and SDR abundance varies by genome and, for SSRs, is proportional to genome size. Long SDRs are rare in the genomes assessed. SSRs occur less frequently than predicted and, although the majority of the repeat motifs do include A and T nucleotides, the A+T bias in SSRs is less than that predicted from the underlying genomic nucleotide composition. In codon usage third positions show an A+T bias, however variation in codon usage does not correlate with differences in A+T-richness. Thus, although plastome nucleotide composition shows "A+T richness", an A+T bias is not apparent upon more in-depth analysis, at least in these aspects. The pattern of evolution in the sequences identified as ycf15 and ycf68 is not consistent with them being protein-coding genes. In fact, these regions show no evidence of sequence conservation beyond what is normal for non-coding regions of the IR.