The g5R (D250) gene of African swine fever virus encodes a Nudix hydrolase that preferentially degrades diphosphoinositol polyphosphates.

The African swine fever virus (ASFV) g5R gene encodes a protein containing a Nudix hydrolase motif which in terms of sequence appears most closely related to the mammalian diadenosine tetraphosphate (Ap4A) hydrolases. However, purified recombinant g5R protein (g5Rp) showed a much wider range of nucleotide substrate specificity compared to eukaryotic Ap4A hydrolases, having highest activity with GTP, followed by adenosine 5'-pentaphosphate (p5A) and dGTP. Diadenosine and diguanosine nucleotides were substrates, but the enzyme showed no activity with cap analogues such as 7mGp3A. In common with eukaryotic diadenosine hexaphosphate (Ap6A) hydrolases, which prefer higher-order polyphosphates as substrates, g5Rp also hydrolyzes the diphosphoinositol polyphosphates PP-InsP5 and [PP]2-InsP4. A comparison of the kinetics of substrate utilization showed that the k(cat)/K(m) ratio for PP-InsP5 is 60-fold higher than that for GTP, which allows classification of g5R as a novel diphosphoinositol polyphosphate phosphohydrolase (DIPP). Unlike mammalian DIPP, g5Rp appeared to preferentially remove the 5-beta-phosphate from both PP-InsP5 and [PP]2-InsP4. ASFV infection led to a reduction in the levels of PP-InsP5, ATP and GTP by ca. 50% at late times postinfection. The measured intracellular concentrations of these compounds were comparable to the respective K(m) values of g5Rp, suggesting that one or all of these may be substrates for g5Rp during ASFV infection. Transfection of ASFV-infected Vero cells with a plasmid encoding epitope-tagged g5Rp suggested localization of this protein in the rough endoplasmic reticulum. These results suggest a possible role for g5Rp in regulating a stage of viral morphogenesis involving diphosphoinositol polyphosphate-mediated membrane trafficking.     

Carrion flies of forensic interest: a study of seasonal community composition and succession in Lisbon,Portugal

Information on Diptera community, seasonality and successional patterns in every geographical region is fundamental for the use of flies as forensic indicators of time of death. In order to obtain these data from the Lisbon area (Portugal), experiments were conducted during the four seasons of the year, using piglet carcasses as animal models. Five stages were recognized during the decomposition process. The stages, besides visually defined, could be separated taking into account the occurrence and abundance of the specific groups of Diptera collected. In general, the bloated stage recorded higher abundance and species‐richness values. Seventy‐one species were identified, belonging to 39 families, in a total of 20 144 adult Diptera collected. Autumn yielded the highest values of species richness, whereas winter had the lowest. In all seasons of the year, Calliphoridae was the dominant family; Muscidae and Fanniidae were very abundant as well. Calliphora vicina Robineau‐Desvoidy, Calliphora vomitoria (Linnaeus), Chrysomya albiceps (Wiedemann), Lucilia ampullacea Villeneuve, Lucilia caesar (Linnaeus), Lucilia sericata (Meigen) (Calliphoridae), Hydrotaea ignava (Harris), Muscina prolapsa (Harris), Synthesiomyia nudiseta (van der Wulp) (Muscidae), Piophila megastigmata McAlpine, Stearibia nigriceps (Meigen) (Piophilidae) and Nemopoda nitidula (Fallén) (Sepsidae) were revealed to be very important members of the Diptera community collected. The necrophagous behaviour, demonstrated by their immatures, using carrion as a food source makes them useful forensic indicator species. Also of relevance is the presence of Chrysomya megacephala (Fabricius), S. nudiseta and P. megastigmata, foreign species established in the local carrion communities. This study also marks the first record of S. nudiseta in Portugal.     

Ultrastructural Studies of Spermiogenesis of Conocephalus saltator (Saussure)

The acrosome of the spermatozoa is the organelle involved in its penetration through the ova membranes during the fertilization process. Several features of this process are considered to be related to the fertilization events e.g. some substance coats outside the membrane. During the maturation process the spermatozoa of Conocephalus saltator develop a coat of tubules and filaments which overly some membrane regions in a specific array. The mature spermatozoa are seen to adhere in these regions and form threads of 20 cells long and five to six wide. It is suggested that the external coat plays a role in this 'sticking' phenomenon.     

Total sleep deprivation does not significantly degrade semantic encoding

ABSTRACT

Sleep deprivation impairs performance on cognitive tasks, but it is unclear which cognitive processes it degrades. We administered a semantic matching task with variable stimulus onset asynchrony (SOA) and both speeded and self-paced trial blocks. The task was administered at the baseline and 24 hours later after 30.8 hours of total sleep deprivation (TSD) or matching well-rested control. After sleep deprivation, the 20% slowest response times (RTs) were significantly increased. However, the semantic encoding time component of the RTs remained at baseline level. Thus, the performance impairment induced by sleep deprivation on this task occurred in cognitive processes downstream of semantic encoding.     

Lactate dehydrogenase (LDH) gene duplication during chordate evolution: the cDNA sequence of the LDH of the tunicate Styela plicata

L-Lactate dehydrogenase (L-LDH, E.C. 1.1.1.27) is encoded by two or three loci in all vertebrates examined, with the exception of lampreys, which have a single LDH locus. Biochemical characterizations of LDH proteins have suggested that a gene duplication early in vertebrate evolution gave rise to Ldh-A and Ldh-B and that an additional locus, Ldh-C arose in a number of lineages more recently. Although some phylogenetic studies of LDH protein sequences have supported this pattern of gene duplication, others have contradicted it. In particular, a number of studies have suggested that Ldh-C represents the earliest divergence among vertebrate LDHs and that it may have diverged from the other loci well before the origin of vertebrates. Such hypotheses make explicit statements about the relationship of vertebrate and invertebrate LDHs, but to date, no closely related invertebrate LDH sequences have been available for comparison. We have attempted to provide further data on the timing of gene duplications leading to multiple vertebrate LDHs by determining the cDNA sequence of the LDH of the tunicate Styela plicata. Phylogenetic analyses of this and other LDH sequences provide strong support for the duplications giving rise to multiple vertebrate LDHs having occurred after vertebrates diverged from tunicates. The timing of these LDH duplications is consistent with data from a number of other gene families suggesting widespread gene duplication near the origin of vertebrates. With respect to the relationships among vertebrate LDHs, our data are not consistent with previous claims that Ldh-C represented the earliest divergence. However, the precise relationships among some of the main lineages of vertebrate LDHs were not resolved in our analyses.