Prevalence and seasonality of Ascogregarina culicis (Apicomplexa: Lecudinidae) in natural populations of Aedes aegypti (Diptera: Culicidae) from temperate Argentina

Ascogregarina infections from South America were recently documented in Brazil and Argentina. The aim of this study was to report our recent findings on the prevalence and seasonality of Ascogregarina culicis in Aedes aegypti adults from temperate Argentina. Between December 2003 and May 2005, 391 females of Ae. aegypti were captured in two areas of Greater Buenos Aires. Overall prevalence of A. culicis was 21.2% (83/391), and a significant difference was observed between both areas (28.4% vs. 8%). Infected Ae. aegypti were found from November to May, with highest values in March (24-37%). Parasite prevalence and host abundance showed similar seasonal patterns. Our observations suggest a widespread infestation of A. culicis among Ae. aegypti populations from temperate Argentina.     

Testing ant predation on the coffee berry borer in shaded and sun coffee plantations in Colombia

Soil‐dwelling ants, many of which are generalist predators, are more diverse in shaded than in sun coffee plantations without trees. We compared ant predation on the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae) in three shaded and three sun coffee plantations in Apía, Colombia, in both the wet and the dry seasons. We found that H. hampei adults exposed to ants for 5 days suffered higher removal in shaded plantations and in the wet season. In the laboratory, we observed that ants killed 74–99% of H. hampei adults over the course of 5 days. Ants appear to be important predators of H. hampei, particularly in shaded coffee plantations and in the wet season.     

DNA polymerase clamp shows little turnover at established replication sites but sequential de novo assembly at adjacent origin clusters

The spatial and temporal organization of DNA replication was investigated in living cells with a green fluorescent protein fusion to the DNA polymerase clamp PCNA. In situ extractions and photobleaching experiments revealed that PCNA, unlike RPA34, shows little if any turnover at replication sites, suggesting that it remains associated with the replication machinery through multiple rounds of Okazaki fragment synthesis. Photobleaching analyses further showed that the transition from earlier to later replicons occurs by disassembly into a nucleoplasmic pool of rapidly diffusing subcomponents and reassembly at newly activated sites. The fact that these replication sites were de novo assembled in close proximity to earlier ones suggests that activation of neighboring origins may occur by a domino effect possibly involving local changes in chromatin structure and accessibility.     

The folding of the hepatitis C virus internal ribosome entry site depends on the 3′-end of the viral genome

Hepatitis C virus (HCV) translation initiation is directed by an internal ribosome entry site (IRES) and regulated by distant regions at the 3′-end of the viral genome. Through a combination of improved RNA chemical probing methods, SHAPE structural analysis and screening of RNA accessibility using antisense oligonucleotide microarrays, here, we show that HCV IRES folding is fine-tuned by the genomic 3′-end. The essential IRES subdomains IIIb and IIId, and domain IV, adopted a different conformation in the presence of the cis-acting replication element and/or the 3′-untranslatable region compared to that taken up in their absence. Importantly, many of the observed changes involved significant decreases in the dimethyl sulfate or N-methyl-isatoic anhydride reactivity profiles at subdomains IIIb and IIId, while domain IV appeared as a more flexible element. These observations were additionally confirmed in a replication-competent RNA molecule. Significantly, protein factors are not required for these conformational differences to be made manifest. Our results suggest that a complex, direct and long-distance RNA–RNA interaction network plays an important role in the regulation of HCV translation and replication, as well as in the switching between different steps of the viral cycle.     

Effects of supplementation with plant extract product containing carvacrol,cinnamaldehyde and capsaicin on serum metabolites and enzymes during the finishing phase of feedlot-fed bull calves

This study investigated the in vivo effects of a commercial blend of plant extracts (carvacrol, cinnamaldehyde and capsaicin) on serum metabolic parameters closely connected with energy and protein metabolism (glucose; l-lactate; non-esterified fatty acids, NEFA; urea nitrogen, SUN; creatinine; total protein, TSP) and enzymes associated with hepatic function (aspartate-aminotransferase, AST and gamma-glutamyl transferase, GGT) in finishing-stage Belgian Blue bull calves maintained in a commercial feedlot. Monitoring was performed over 86 days in 24 animals randomly allotted to two groups: (1) a control group (CTR, no supplementation; n = 10), and (2) a group receiving dietary supplementation with a commercial blend of plant extracts (PEX, 100 mg/kg DM of concentrate; n = 14). Under the conditions of our study, supplementation with the commercial blend did not give detrimental effects, but the opposite: the decrease in serum l-lactate, NEFA and creatinine levels and the increase in SUN concentrations; suggests an improvement in the energy status and protein turnover of the supplemented animals.     

Large and dissimilar repertoire of Melan-A/MART-1-specific CTL in metastatic lesions and blood of a melanoma patient

It is widely accepted that the repertoire of Melan-A-specific T cells naturally selected in melanoma patients is diverse and mostly nonoverlapping among different individuals. To date, however, no studies have addressed the TCR profile in different tumor sites and the peripheral blood from the same patient. We compared the TCR usage of Melan-A-specific T cells from different compartments of a single melanoma patient to evaluate possible clonotype expansion or preferential homing over a 4-mo follow-up period. Using HLA-A2 peptide tetramers, CD8(+) T cells recognizing the modified Melan-A immunodominant ELAGIGILTV peptide were isolated from four metastatic lesions resected from a single melanoma patient, and their TCR repertoire was studied. A panel of T cell clones was generated by cell cloning of tetramer-positive cells. Analysis of the TCR beta-chain V segment and the complementarity-determining region 3 (CDR3) length and sequence revealed a large diversity in the TCR repertoire, with only some of the clones showing a partial conservation in the CDR3. A similar degree of diversity was found by analyzing a number of T cell clones obtained after sorting a Melan-A-specific population derived from PBLs of the same patient after in vitro culture with the immunodominant epitope. Moreover, clonotypes found at one site were not present in another, suggesting the lack of expansion and circulation of one or more clonotypes. Taken together, these results buttress the notion that the CTLs recognizing the immunodominant Ag of Melan-A comprise a high number of different clonotypic TCR, of which only some exhibit common features in the CDR3.     

A study to sustain the hypothesis of the multiple genesis of oligoasthenoteratospermia in human idiopathic infertile males

Interdependence between sperm concentration, motility, morphology, and the percentage of aneuploid sperm was explored to test whether oligoasthenoteratospermia (OAT) may have a multiple origin in idiopathic infertile males. A total of 174 men (age, 35.8 +/- 4.3 yr) with idiopathic infertility were studied. Seven patients had nonobstructive azoospermia, 55 had severe OAT, 30 had OAT, 27 had isolated alterations of motility, 45 had alterations of morphology and of motility, and 10 had isolated alterations of morphology. The sperm morphology was assessed with strict criteria. The percentage of aneuploid sperm was assessed with fluorescent in situ hybridization for chromosomes X, Y, 13, 15, 16, 17, 18, 21, and 22. Relationships between sperm features, and the relationship between sperm features and aneuploidies were analyzed with multivariate regression analysis. Statistical analysis did not find any significant relationship between the percentage of typical forms and sperm concentration or between morphology and motility. On the other hand, a positive and significant relationship was found between sperm concentration and motility. The percentage of aneuploid sperm was inversely and significantly related to the percentage of typical forms but not to motility and concentration. Sperm morphology is an independent characteristic with respect to concentration and motility, whereas it showed a significant inverse relationship with respect to the percentage of aneuploid sperm. This means that idiopathic OAT may occur by means of at least two independent pathways, the first affecting concentration and/or motility and the second affecting morphology.     

Deletion of PsbM in tobacco alters the QB site properties and the electron flow within photosystem II

Photosystem II, the oxygen-evolving complex of photosynthetic organisms, includes an intriguingly large number of low molecular weight polypeptides, including PsbM. Here we describe the first knock-out of psbM using a transplastomic, reverse genetics approach in a higher plant. Homoplastomic Delta psbM plants exhibit photoautotrophic growth. Biochemical, biophysical, and immunological analyses demonstrate that PsbM is not required for biogenesis of higher order photosystem II complexes. However, photosystem II is highly light-sensitive, and its activity is significantly decreased in Delta psbM, whereas kinetics of plastid protein synthesis, reassembly of photosystem II, and recovery of its activity are comparable with the wild type. Unlike wild type, phosphorylation of the reaction center proteins D1 and D2 is severely reduced, whereas the redox-controlled phosphorylation of photosystem II light-harvesting complex is reversely regulated in Delta psbM plants because of accumulation of reduced plastoquinone in the dark and a limited photosystem II-mediated electron transport in the light. Charge recombination in Delta psbM measured by thermoluminescence oscillations significantly differs from the 2/6 patterns in the wild type. A simulation program of thermoluminescence oscillations indicates a higher Q(B)/Q(-)(B) ratio in dark-adapted mutant thylakoids relative to the wild type. The interaction of the Q(A)/Q(B) sites estimated by shifts in the maximal thermoluminescence emission temperature of the Q band, induced by binding of different herbicides to the Q(B) site, is changed indicating alteration of the activation energy for back electron flow. We conclude that PsbM is primarily involved in the interaction of the redox components important for the electron flow within, outward, and backward to photosystem II.     

An ancient mechanism of hindbrain patterning has been conserved in vertebrate evolution

The hindbrain is a vertebrate-specific embryonic structure of the central nervous system formed by iterative transitory units called rhombomeres (r). Rhombomeric cells are segregated by interhombomeric boundaries which are prefigured by sharp gene expression borders. The positioning of the first molecular boundary within the hindbrain (the prospective r4/r5 boundary) responds to the expression of an Iroquois (Irx) gene in the anterior (r4) and the gene vHnf1 at the posterior (r5). However, while Irx3 is expressed anteriorly in amniotes, a novel Irx gene, iro7, acts in teleosts. To assess the evolutionary history of the genes responsible for the positioning of the r4/r5 boundary in vertebrates, we have stepped outside the gnathostomes to investigate these genes in the agnathans Lethenteron japonicum and Petromyzon marinus. We identified one representative of the Hnf1 family in agnathans. Its expression pattern recapitulates that of vHnf1 and Hnf1 in higher vertebrates. Our phylogenetic analysis places this gene basal to gnathostome Hnf1 and vHnf1 genes. We propose that the duplication of an ancestral hnf1 gene present in the common ancestor of agnathans and gnathostomes gave rise to the two genes found in gnathostomes. We have also amplified 3 Irx genes in L. japonicum: LjIrxA, LjIrxC, LjIrxD. The expression pattern of LjIrxA (the agnathan Irx1/3 ortholog) resembles those of Irx3 or iro7 in gnathostomes. We propose that an Irx/hnf1 pair already present in early vertebrates positioned the r4/r5 boundary and that gene duplications occurred in these gene families after the divergence of the agnathans.