Nuclear DNA from old collections of avian study skins reveals the evolutionary history of the Old World suboscines (Aves, Passeriformes)

Museum study skins represent an invaluable source of DNA for phylogenetics, phylogeography and population genetics. This becomes evident by comparing the number of study skins of birds housed in museums worldwide ( c . 10 million) with the corresponding number of tissue samples (probably fewer than 500 000). While the laboratory techniques used hitherto have primarily allowed PCR-based studies of mitochondrial genes from museum skins, we present here the first avian phylogeny based on a large number of nuclear sequences. The targeted fragment sizes and the properties of the primers used are important contributory factors to obtain good amplification results. In this study we routinely amplified fragments of c. 350 bp nuclear DNA. This advance in methodology opens up a new avenue for the use of avian museum skins, as nuclear DNA is especially useful when studying ancient patterns of diversification. The phylogenetic hypothesis of the Old World suboscines (Eurylaimides) presented herein strongly supports a monophyletic origin of the pittas (Pittidae). The phylogeny further suggests that pittas could be divided into three major groups, in agreement with the external morphological variation found in this group. The broadbills (Eurylaimidae) as currently defined are, on the other hand, found to be a paraphyletic family, as both Sapayoa aenigma and the asities (Philepittidae) are nested among them. Based on the phylogenetic results we suggest a revised classification of the Old World suboscines (Eurylaimides).     

Tactile stimulation-induced rapid elevation of the synaptophysin mRNA expression level in rat somatosensory cortex

Synaptophysin is an integral membrane protein abundant in the synaptic vesicle and is found in nerve terminals throughout the brain. It was recently suggested that synaptophysin is also involved in the modulation of activity-dependent synapse formation. In this study, we examined at the individual level whether tactile stimulation selectively influenced the synaptophysin mRNA expression level in the somatosensory cortex of rats. Anesthetized rats were caressed on the back by an experimenter's palms for 20 min and the mRNA expression levels in the somatosensory and the visual cortices 5 min afterwards were determined using quantitative PCR methodology. The synaptophysin mRNA expression level was selectively higher in the experimental group than in the control group in the somatosensory cortex but not in the visual cortex. This suggests that the mRNA expression level of synaptophysin induced by neuronal activity is related to the regulation of synapse formation or remodeling or both.     

Impact on growth and aflatoxin B1 accumulation by Kluyveromyces isolates at different water activity conditions

This study showed the impact on germination, mycelial growth and aflatoxin B₁ accumulation when interacting Aspergillus aflatoxigenic strains with Kluyveromyces isolates and the effect of water activity on this relationship. Isolates Y₁₄ and Y₁₆ reduced the percentage of germination of all Aspergillus strains and decrease germ tube elongation rate at majority of water activity assayed. Similarly they produced an increase of germination lag phase and lag phase of growth beside decreased growth rate of all Aspergillus strains. At water activities 0.994, 0.982, 0.955 and 0.937, no aflatoxins were produced in paired cultures with isolates Y_25, Y₂₂, Y₁₆, and Y₁₄, and Kluyveromyces isolates Y₁₄ and Y₁₆ impact both growth and aflatoxin accumulation at wide range of water activity.     

Binding of human SLBP on the 3'-UTR of histone precursor H4-12 mRNA induces structural rearrangements that enable U7 snRNA anchoring

In metazoans, cell-cycle-dependent histones are produced from poly(A)-lacking mRNAs. The 3′ end of histone mRNAs is formed by an endonucleolytic cleavage of longer precursors between a conserved stem–loop structure and a purine-rich histone downstream element (HDE). The cleavage requires at least two trans-acting factors: the stem–loop binding protein (SLBP), which binds to the stem–loop and the U7 snRNP, which anchors to histone pre-mRNAs by annealing to the HDE. Using RNA structure-probing techniques, we determined the secondary structure of the 3′-untranslated region (3′-UTR) of mouse histone pre-mRNAs H4–12, H1t and H2a–614. Surprisingly, the HDE is embedded in hairpin structures and is therefore not easily accessible for U7 snRNP anchoring. Probing of the 3′-UTR in complex with SLBP revealed structural rearrangements leading to an overall opening of the structure especially at the level of the HDE. Electrophoretic mobility shift assays demonstrated that the SLBP-induced opening of HDE actually facilitates U7 snRNA anchoring on the histone H4–12 pre-mRNAs 3′ end. These results suggest that initial binding of the SLBP functions in making the HDE more accessible for U7 snRNA anchoring.     

Incidence of pituitary tumors in the human population of Croatia

Pituitary tumors are rare tumors (less then 10%) of the central nervous system (CNS), which malignicity depends on their localization, meanwhile, their biological nature is benign. The diameter they have is mostly less then 10 mm (microadenomas), but sometimes could be 10 mm (macroadenomas) to 5 cm and more and then are usually nonfunctional (about 20% of all pituitary tumors). Clinical presence depends on their localisation and hormonal activity. In the Center for Clinical Neuroendocrinology and Pituitary Diseases, in the last working 10 years, there were treated and examined 504 patients from Croatia, all with pituitary tumors: 182 patients with prolactinomas, 137 with acromegaly, 70 with Morbus Cushing (Mb. Cushing), and 115 patients with nonfunctional pituitary tumors. The patient's classification is based on regional (Mediterranean and continental region, 20 counties) and the state level. In our analysis we haven't found difference in incidence of tumors between Mediterranean and continental region.     

PHENOPSIS, an automated platform for reproducible phenotyping of plant responses to soil water deficit in Arabidopsis thaliana permitted the identification of an accession with low sensitivity to soil water deficit

The high-throughput phenotypic analysis of Arabidopsis thaliana collections requires methodological progress and automation. Methods to impose stable and reproducible soil water deficits are presented and were used to analyse plant responses to water stress. Several potential complications and methodological difficulties were identified, including the spatial and temporal variability of micrometeorological conditions within a growth chamber, the difference in soil water depletion rates between accessions and the differences in developmental stage of accessions the same time after sowing. Solutions were found. Nine accessions were grown in four experiments in a rigorously controlled growth-chamber equipped with an automated system to control soil water content and take pictures of individual plants. One accession, An1, was unaffected by water deficit in terms of leaf number, leaf area, root growth and transpiration rate per unit leaf area. Methods developed here will help identify quantitative trait loci and genes involved in plant tolerance to water deficit.     

Presence of free myxol and 4-hydroxymyxol and absence of myxol glycosides in Anabaena variabilis ATCC 29413, and proposal of a biosynthetic pathway of carotenoids

We identified the molecular structures of all carotenoids in Anabaena variabilis ATCC 29413 (= IAM M-204). The major carotenoids were beta-carotene, echinenone and canthaxanthin. Myxol glycosides were absent, while free forms of myxol and 4-hydroxymyxol were present. The 4-hydroxyl group of the latter was a mixture of (4R) and (4S) configurations, which is a rare mixture in carotenoids. Thus, this strain was the first cyanobacterium found to have free myxol and not myxol glycosides, and seemed to lack the gene for or activity of glycosyl transferase. In another strain of A. variabilis IAM M-3 (= PCC 7118), we recently identified (3R,2'S)-myxol 2'-fucoside and (3S,2'S)-4-ketomyxol 2'-fucoside, and hence the strain ATCC 29413 might be useful for investigating the characteristics of myxol glycosides in cyanobacteria. Based on the identification of the carotenoids and the completion of the entire nucleotide sequence of the genome in A. variabilis ATCC 29413, we proposed a biosynthetic pathway of the carotenoids and the corresponding genes and enzymes. The homologous genes were searched by sequence homology only from the functionally confirmed genes.     

Nitrate-dependent control of root architecture and N nutrition are altered by a plant growth-promoting Phyllobacterium sp

Both root architecture and plant N nutrition are altered by inoculation with the plant growth-promoting rhizobacteria (PGPR) Phyllobacterium strain STM196. It is known that NO₃⁻ and N metabolites can act as regulatory signals on root development and N transporters. In this study, we investigate the possible interrelated effects on root development and N transport. We show that the inhibition of Arabidopsis lateral root growth by high external NO₃⁻ is overridden by Phyllobacterium inoculation. However, the leaf NO₃⁻ pool remained unchanged in inoculated plants. By contrast, the Gln root pool was reduced in inoculated plants. Unexpectedly, NO₃⁻ influx and the expression levels of AtNRT1.1 and AtNRT2.1 genes coding for root NO₃⁻ transporters were also decreased after 8 days of Phyllobacterium inoculation. Although the mechanisms by which PGPR exert their positive effects remain unknown, our data show that they can optimize plant development independently from N supply, thus alleviating the regulatory mechanisms that operate in axenic conditions. In addition, we found that Phyllobacterium sp. elicited a very strong induction of AtNRT2.5 and AtNRT2.6, both genes preferentially expressed in the shoots whose functions are unknown.     

Short synthesis of 16beta-hydroxy-5alpha-cholestane-3,6-dione a novel cytotoxic marine oxysterol

The first and short synthesis of 16beta-hydroxy-5alpha-cholestane-3,6-dione 1 a metabolite from marine algae, has been achieved in six steps from readily available diosgenin 5. Selective deoxygenation of primary alcohol of triol 6 has been accomplished in one step using Et(3)SiH and catalytic amount of B(C(6)F(5))(3) to produce compound 9 in high yield. Oxidation of 11 with PCC, allowed the introduction of 3,6-ene-dione functionality, and further catalytic hydrogenation and deprotection furnished the 3,6-diketo steroid 1.