Comparison of the oxidative phosphorylation (OXPHOS) nuclear genes in the genomes of Drosophila melanogaster, Drosophila pseudoobscura and Anopheles gambiae

Background

In eukaryotic cells, oxidative phosphorylation (OXPHOS) uses the products of both nuclear and mitochondrial genes to generate cellular ATP. Interspecies comparative analysis of these genes, which appear to be under strong functional constraints, may shed light on the evolutionary mechanisms that act on a set of genes correlated by function and subcellular localization of their products.

Results

We have identified and annotated the Drosophila melanogaster, D. pseudoobscura and Anopheles gambiae orthologs of 78 nuclear genes encoding mitochondrial proteins involved in oxidative phosphorylation by a comparative analysis of their genomic sequences and organization. We have also identified 47 genes in these three dipteran species each of which shares significant sequence homology with one of the above-mentioned OXPHOS orthologs, and which are likely to have originated by duplication during evolution. Gene structure and intron length are essentially conserved in the three species, although gain or loss of introns is common in A. gambiae. In most tissues of D. melanogaster and A. gambiae the expression level of the duplicate gene is much lower than that of the original gene, and in D. melanogaster at least, its expression is almost always strongly testis-biased, in contrast to the soma-biased expression of the parent gene.

Conclusions

Quickly achieving an expression pattern different from the parent genes may be required for new OXPHOS gene duplicates to be maintained in the genome. This may be a general evolutionary mechanism for originating phenotypic changes that could lead to species differentiation.     

Dispersion and transport of Cryptosporidium Oocysts from fecal pats under simulated rainfall events

The dispersion and initial transport of Cryptosporidium oocysts from fecal pats were investigated during artificial rainfall events on intact soil blocks (1,500 by 900 by 300 mm). Rainfall events of 55 mm h(-1) for 30 min and 25 mm h(-1) for 180 min were applied to soil plots with artificial fecal pats seeded with approximately 10(7) oocysts. The soil plots were divided in two, with one side devoid of vegetation and the other left with natural vegetation cover. Each combination of event intensity and duration, vegetation status, and degree of slope (5 degrees and 10 degrees ) was evaluated twice. Generally, a fivefold increase (P < 0.05) in runoff volume was generated on bare soil compared to vegetated soil, and significantly more infiltration, although highly variable, occurred through the vegetated soil blocks (P < 0.05). Runoff volume, event conditions (intensity and duration), vegetation status, degree of slope, and their interactions significantly affected the load of oocysts in the runoff. Surface runoff transported from 10(0.2) oocysts from vegetated loam soil (25-mm h(-1), 180-min event on 10 degrees slope) to up to 10(4.5) oocysts from unvegetated soil (55-mm h(-1), 30-min event on 10 degrees slope) over a 1-m distance. Surface soil samples downhill of the fecal pat contained significantly higher concentrations of oocysts on devegetated blocks than on vegetated blocks. Based on these results, there is a need to account for surface soil vegetation coverage as well as slope and rainfall runoff in future assessments of Cryptosporidium transport and when managing pathogen loads from stock grazing near streams within drinking water watersheds.     

PCR amplification of crude microbial DNA extracted from soil

A rapid, inexpensive, large-scale DNA extraction method involving minimal purification hasbeen developed that is applicable to various soil types. DNA was extracted from 100 g of soilusing direct lysis with glass beads and sodium dodecyl sulphate (SDS) followed by polyethyleneglycol precipitation, potassium acetate precipitation, phenol extraction and isopropanolprecipitation. The crude extract could be used in PCR directed at high-copy number (bacterialsmall subunit rRNA) and single-copy (fungal β-tubulin) genes.     

Stamen elongation,pollen size,and siring ability in tristylous elchhornia paniculata (Pontederiaceae)

Selfing variants in tristylous Eichhornia paniculata (Pontederiaceae) possess an elongated, short-level stamen adjacent to mid-level stigmas, which causes autonomous selfing. The variants commonly spread in dimorphic, but not trimorphic populations in northeast Brazil. We investigated the effect of stamen elongation on pollen size and siring ability. Competition experiments using controlled hand-pollination and allozyme markers were used to compare different pollen types. Pollen from the elongated stamen was significantly larger in size than pollen from unmodified short-level stamens. In mixed pollinations of mid-level stigmas, pollen from the elongated stamen sired significantly more seed than pollen from unmodified short-level stamens. Despite these differences, the size and compatibility of pollen from the elongated stamen were more similar to short- than mid-level pollen, indicating that alterations to stamen level were not associated with major changes in pollen characteristics. The results suggest that the advantage of selfing variants in dimorphic populations is mainly due to efficient pollen transfer to mid-level stigmas rather than increased postpollination siring success of pollen from modified stamens. In addition, the absence of major changes in pollen size and compatibility associated with stamen elongation support other lines of evidence indicating that selfing variants are not the result of recombination in the putative heterostyly supergene.     

Cloricromene antagonizes antidipsogenic effects induced by endotoxin, but not by TNF alpha, in the rat.

Intravenous (640 micrograms/kg) or intracerebroventricular (0.5 and 1 microgram) injection of Escherichia coli endotoxin (LPS) causes inhibition of water intake induced by 24 hour period of water deprivation in the rat. Tumor necrosis factor alpha (TNF-alpha; 20 and 40 ng/rat) given into the lateral cerebral ventricle (i.c.v.) causes effects similar to those observed after LPS. Cloricromene, given either intravenously (1 and 2 mg/kg) or i.c.v. (250 and 500 ng), abolished the antidipsogenic effect induced by LPS (administered both i.v. and i.c.v.). Cloricromene (2 mg/kg, i.v. or 500 ng/rat, i.c.v.), on the contrary, did not modify the antidipsogenic effects induced by TNF-alpha. These data indicate that peripherally injected cloricromene (as well as that i.c.v. injected) antagonizes the effects of mediators of LPS on sites regulating thirst and suggest that cloricromene's action may be due to inhibition of brain TNF-alpha formation induced by LPS.     

Thiophenyl-substituted triazolyl-thione l-alanine: asymmetric synthesis,aggregation and biological properties

In this work, we report the asymmetric synthesis and characterization of an artificial amino acid based on triazolyl-thione l-alanine, which was modified with a thiophenyl-substituted moiety, as well as in vitro studies of its nucleic acid-binding ability. We found, by dynamic light scattering studies, that the synthetic amino acid was able to form supramolecular aggregates having a hydrodynamic diameter higher than 200 nm. Furthermore, we demonstrated, by UV and CD experiments, that the heteroaromatic amino acid, whose enzymatic stability was demonstrated by HPLC analysis also after 24 h of incubation in human serum, was able to bind a RNA complex, which is a feature of biomedical interest in view of innovative antiviral strategies based on modulation of RNA–RNA molecular recognition.     

Sox9 and Hif-2α regulate TUBB3 gene expression and affect ovarian cancer aggressiveness

SOX9 [(sex determining region Y)-box9] gene has been implicated in the development and progression of different neoplasms. This study investigated the role of Sox9 in the expression of TUBB3 gene, a marker of aggressiveness in ovarian cancer (OC), encoding βIII-tubulin protein. Gene expression was assessed by quantitative polymerase chain reaction (qPCR) in OC models.     

Constitutive patterns of gene expression regulated by RNA-binding proteins

Background

RNA-binding proteins regulate a number of cellular processes, including synthesis, folding, translocation, assembly and clearance of RNAs. Recent studies have reported that an unexpectedly large number of proteins are able to interact with RNA, but the partners of many RNA-binding proteins are still uncharacterized.

Results

We combined prediction of ribonucleoprotein interactions, based on catRAPID calculations, with analysis of protein and RNA expression profiles from human tissues. We found strong interaction propensities for both positively and negatively correlated expression patterns. Our integration of in silico and ex vivo data unraveled two major types of protein–RNA interactions, with positively correlated patterns related to cell cycle control and negatively correlated patterns related to survival, growth and differentiation. To facilitate the investigation of protein–RNA interactions and expression networks, we developed the catRAPID express web server.

Conclusions

Our analysis sheds light on the role of RNA-binding proteins in regulating proliferation and differentiation processes, and we provide a data exploration tool to aid future experimental studies.     

Subtractive and differential hybridization molecular analyses of <Emphasis Type="Italic">Ceratitis capitata</Emphasis> XX/XY versus XX embryos to search for male-specific early transcribed genes

The agricultural pest Ceratitis capitata, also known as the Mediterranean fruit fly or Medfly, is a fruit crop pest of very high economic relevance in different continents. The strategy to separate Ceratitis males from females (sexing) in mass rearing facilities is a useful step before the sterilization and release of male-only flies in Sterile Insect Technique control programs (SIT). The identification of genes having early embryonic male-specific expression, including Y-linked genes, such as the Maleness factor, could help to design novel and improved methods of sexing in combination with transgenesis, aiming to confer conditional female-specific lethality or female-to-male sexual reversal.We used a combination of Suppression Subtractive Hybrydization (SSH), Mirror Orientation Selection (MOS) and differential screening hybridization (DSH) techniques to approach the problem of isolating corresponding mRNAs expressed in XX/XY embryos versus XX-only embryos during a narrow developmental window (8-10 hours after egg laying, AEL ). Here we describe a novel strategy we have conceived to obtain relatively large amounts of XX-only embryos staged at 8-10 h AEL and so to extract few micrograms of polyA+ required to apply the complex technical procedure. The combination of these 3 techniques led to the identification of a Y-linked putative gene, CcGm2, sharing high sequence identity to a paralogous gene, CcGm1, localized either on an autosome or on the X chromosome.We propose that CcGm2 is a first interesting putative Y-linked gene which could play a role in sex determination. The function exterted by this gene should be investigated by novel genetic tools, such as CRISPR-CAS9, which will permit to target only the Y-linked paralogue, avoiding to interfere with the autosomal or X-linked paralogue function.