Isolation of three novel Drosophila melanogaster genes containing repetitive sequences rich in GCN triplets.

Several cDNA and genomic clones were isolated from Drosophila melanogaster gene libraries by hybridization with a region of a mammalian gene that contains a simple repetitive sequence of six GCN repeats. One of the cDNA clones, E6, was completely sequenced and it was shown that it contains a region of 16 GCN repeats; these repeats encode a polyalanine stretch within a long open reading frame. The sequencing of three different genomic clones (A, B, and D) revealed that all the isolated Drosophila clones are similar to one another in a short region containing variable numbers of the GCN repeat. The genomic clone B was found to be the genomic counterpart of the cDNA clone E6. The other genomic clones, A and D, also hybridize with Drosophila cDNA clones at high stringency. These results indicate that the short GCN repetitive sequences, which we have named ala, are found within transcribed regions of the Drosophila genome. These Drosophila genes containing the ala repeat do not show significant sequence similarity to any presently known gene; we have named these novel genes ala-A, ala-B, and ala-D. The cDNA clone from gene ala-B was named ala-E6.     

Discord in the family Sparidae (Teleostei): divergent phylogeographical patterns across the Atlantic-Mediterranean divide

The Strait of Gibraltar has been proposed to be the divide between two marine biogeographical regions, the Mediterranean Sea and the Northeast Atlantic. Intraspecific studies have shown, for several of the examined species, a reduction of gene flow between the two basins. The present study examines genetic variation at nuclear and mitochondrial loci in five marine teleost species belonging to the family Sparidae. Four samples for each species were analysed spanning the Northeast Atlantic and the Mediterranean. For all individuals 17 allozyme loci were scored and a combined single strand conformation polymorphism-sequencing approach was used to survey approximately 190 bp of the mitochondrial DNA (mtDNA) D-loop region. All five species share similar biological features. For three species, namely Lithognathus mormyrus, Spondyliosoma cantharus, and Dentex dentex, large mtDNA divergence was observed between Atlantic and Mediterranean samples. Little or no mtDNA differentiation was found in the other two species, Pagrus pagrus and Pagellus bogaraveo. Allozyme data revealed strong differentiation when comparing Atlantic and Mediterranean samples of L. mormyrus and D. dentex, moderate for P. pagrus, and no differentiation for P. bogaraveo and S. cantharus. These results provide evidence for a sharp phylogeographical break (sensu Avise) between the Atlantic and the Mediterranean for two (or possibly three) sparid species of the five investigated. At the same time, the obtained results for the other two species raise the question on which ecological/historical factors might have caused the observed discrepancy in the geographical distribution of genetic variation among otherwise biologically similar species.     

Separate effects of triploidy, parentage and genomic diversity upon feeding behaviour, metabolic efficiency and net energy balance in the Pacific oyster Crassostrea gigas

Triploid oysters were induced using cytochalasin B upon retention of either the first (meiosis I triploids) or the second (meiosis II triploids) polar body in embryos from a single cohort derived from mixed parentage. Allozyme and microsatellite assays enabled the confirmation of both parentage and triploidy status in each oyster. Comparison of meiosis I triploids, meiosis II triploids and diploid siblings established that improved physiological performance in triploids was associated with increased allelic variation, rather than with the quantitative dosage effects of ploidy status. An unidentified maternal influence also interacted with genotype. Among full sibs, allelic variation measured as multi-locus enzyme heterozygosity accounted for up to 42% of the variance in physiological performance; significant positive influences were identified upon feeding rate, absorption efficiency, net energy balance and growth efficiency (= net energy balance divided by energy absorbed). Whilst allelic variation was greater in both meiosis I and meiosis II triploids than in diploid siblings, both allelic variation and net energy balance were highest in triploids induced at meiosis I. This suggests that it may be preferable to induce triploidy by blocking meiosis I, rather than meiosis II as has traditionally been undertaken during commercial breeding programmes.     

Similar hypotensive responses to resistance exercise with and without blood flow restriction

Low intensity resistance exercise (RE) with blood flow restriction (BFR) has gained attention in the literature due to the beneficial effects on functional and morphological variables, similar to those observed during traditional RE without BFR, while the effects of BFR on post-exercise hypotension remain unclear. The aim of the present study was to compare the blood pressure (BP) response of trained normotensive individuals to RE with and without BFR. In this cross-over randomized trial, eight male subjects (23.8 ± 4 years, 74 ± 3 kg, 174 ± 4 cm) completed two exercise protocols: traditional RE (3 x 10 repetitions at 70% one-repetition maximum [1-RM]) and low intensity RE (3 x 15 repetitions at 20% 1-RM) with BFR. Blood pressure measurements were performed after 15 min of seated rest (0), immediately after and 10 min, 20 min, 30 min, 40 min, 50 min and 60 min after the experimental sessions. Similar hypotensive effects for systolic BP (SBP) were observed for both protocols (P < 0.05) after exercise, with no differences between groups (P > 0.05) and no statistically significant difference for diastolic BP (P > 0.05). These results suggest that in normotensive trained individuals, both traditional RE and RE with BFR induce hypotension for SBP, which is important to prevent cardiovascular disturbances.     

Origin, diversification, and historical biogeography of the genus Trachurus (Perciformes: Carangidae)

We addressed phylogenetic relationships in the genus Trachurus using cytochrome b gene and D-loop sequences. The trees showed five groups: (1) the Southwest Pacific species (T. japonicus, T. novaezelandiae, and T. declivis); (2) The Mediterranean Sea and Eastern Atlantic species (T. mediterraneus); (3) The Atlantic Ocean species (T. lathami and T. trecae); (4) Eastern Atlantic species (T. trachurus and T. capensis); and (5) a group of highly mobile pelagic species, two from the Eastern Pacific (T. symmetricus and T. murphyi) and one from the Eastern Atlantic (T. picturatus). The phylogeny based on Cyt b, supports the molecular clock hypothesis and our results agree with the reported fossil indicating that the origin of this genus occur when the Thetys Sea closed (around 18.4 MYA). In addition, a very slow neutral substitution rate is reported identified only two periods of maximum diversification: the first occurring between 18.4 and 15.0 MYA and the second between 8.4 MYA and present day.     

The shaping of mitochondrial DNA phylogeographic patterns of the brown hare (Lepus europaeus) under the combined influence of Late Pleistocene climatic fluctuations and anthropogenic translocations

The phylogeographic structure of the brown hare (Lepus europaeus) was studied by analysing mtDNA control region sequences of 98 individuals from continental and insular Greece, Bulgaria, Cyprus and northern Israel, together with 44 published sequences from Italy and central Europe. We found two distinct clades separated by an average nucleotide divergence of 6.6%, which may correspond to a Balkan and to an Asia Minor refugium. The estimated time of separation of the two clades was dated back to 105,000- 490,000 years ago. These two clades coexist in the area of northeastern Greece and Bulgaria, most likely as a result of a post-glacial northward expansion. Within the southern Balkan refugium, network analyses showed geographical structuring, which supports the hypothesis of several isolated Late Pleistocene populations. The central European and Italian populations appear to have originated from a non-detected northern Balkan population that was genetically closely related to some northern Greek populations, as a result of postglacial expansion, translocations or a combination of both. Moreover, several cases of ancient and recent translocations by humans were detected, especially for some island populations, while the eastern Aegean islands off the Asia Minor coast were most likely colonized naturally through Late Pleistocene land bridge connection. The genetic analysis presented here provides a framework for designing proper conservation and management guidelines for this species.     

Identification of an evolutionary conserved SURF-6 domain in a family of nucleolar proteins extending from human to yeast

The mammalian SURF-6 protein is localized in the nucleolus, yet its function remains elusive in the recently characterized nucleolar proteome. We discovered by searching the Protein families database that a unique evolutionary conserved SURF-6 domain is present in the carboxy-terminal of a novel family of eukaryotic proteins extending from human to yeast. By using the enhanced green fluorescent protein as a fusion protein marker in mammalian cells, we show that proteins from distantly related taxonomic groups containing the SURF-6 domain are localized in the nucleolus. Deletion sequence analysis shows that multiple regions of the SURF-6 protein are capable of nucleolar targeting independently of the evolutionary conserved domain. We identified that the Saccharomyces cerevisiae member of the SURF-6 family, named rrp14 or ykl082c, has been categorized in yeast databases to interact with proteins involved in ribosomal biogenesis and cell polarity. These results classify SURF-6 as a new family of nucleolar proteins in the eukaryotic kingdom and point out that SURF-6 has a distinct domain within the known nucleolar proteome that may mediate complex protein-protein interactions for analogous processes between yeast and mammalian cells.