Cytogenetic Analysis of A- and B-Chromosomes of Prochilodus Lineatus (Teleostei, Prochilodontidae) Using Different Restriction Enzyme Banding and Staining Methods

Different cytogenetic techniques were used to analyse the chromosomes of Prochilodus lineatus with the main objective of comparing the base composition of A- and B-chromosomes. The results of digestion of chromosomes with 10 different restriction endonucleases (REs), silver staining, CMA₃ staining and C-banding indicated the existence of different classes of highly repetitive DNA in the A-set and also suggested the existence of compositional differences between the chromatin of A- and B-chromosomes. The 5-BrdU incorporation technique showed a late replicating pattern in all B-chromosomes and in some heterochromatic pericentromeric regions of A-chromosomes. The cleavage with RE BamHI produced a band pattern in all chromosomes of P. lineatus which permitted the tentative pairing of homologues in the karyotype of this species. We concluded that the combined use of the above techniques can contribute to the correct identification of chromosomes and the karyotypic analysis in fishes. On the basis of the results, some aspects of chromosome structure and the origin of the B-chromosomes in P. lineatus are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Spermatozoa ultrastructure of the pink shrimp Farfantepenaeus paulensis (Decapoda: Dendrobranchiata)

Braga, A.L., Nakayama, C.L., Suita de Castro, L.A. and Wasielesky, W. 2011. Spermatozoa ultrastructure of the pink shrimp Farfantepenaeus paulensis (Decapoda: Dendrobranchiata). —Acta Zoologica (Stockholm) 00 : 1–6. The spermatozoa ultrastructure of the pink shrimp Farfantepenaeus paulensis was investigated in this morphological study. Spermatophores and spermatozoa were analyzed by electron microscopy. The pink shrimp spermatophore is divided into two regions: the appendage and the spermatophore main body, where spermatozoa are grouped in a spermatic mass. Pink shrimp spermatozoa are unistellate and are composed of main body and single spike. The spermatozoa body comprises a perinuclear cytoplasmic band, nucleus, acrosomal cap, and subacrosomal region. The spermatozoa cell mean total length was 10.71 μm, the mean body diameter was 5.56 μm, and the mean spike length and diameter were 5.15 μm and 0.85 μm, respectively.     

Sequence analysis of the 2009 pandemic influenza A H1N1 virus haemagglutinin gene from 2009-2010 Brazilian clinical samples

In this paper, we analysed the haemagglutinin (HA) gene identified by polymerase chain reaction from 90 influenza A H1N1 virus strains that circulated in Brazil from April 2009-June 2010. A World Health Organization sequencing protocol allowed us to identify amino acid mutations in the HA protein at positions S220T (71%), D239G/N/S (20%), Y247H (4.5%), E252K (3.3%), M274V (2.2%), Q310H (26.7%) and E391K (12%). A fatal outcome was associated with the D239G mutation (p < 0.0001). Brazilian HA genetic diversity, in comparison to a reference strain from California, highlights the role of influenza virus surveillance for study of viral evolution, in addition to monitoring the spread of the virus worldwide.     

Profilin inhibits pollen tube growth through actin-binding,but not poly-<Emphasis Type="SmallCaps">l</Emphasis>-proline-binding

Previously, we have shown that excess profilin inhibits pollen tube growth at significantly lower concentrations than it blocks cytoplasmic streaming. To elucidate the mechanism by which profilin achieves this function, we have employed mutant profilins from Schizosaccharomyces pombe [J. Lu and T.D. Pollard (2001) Mol Biol Cell 12:1161–1175], which have defects in actin-binding, ability to inhibit polymerization, and poly-l-proline (PLP)-binding. Using Lilium longiflorum L. pollen and S. pombe profilins as wild-type (wt) standards, mutant profilins have been injected into pollen tubes of Lilium, and examined for their effects on growth rate and cell morphology. Our results show that mutant Y5D (68% actin-binding; 1.1% PLP-binding) is indistinguishable from wt-standard profilins. However mutant K81F (2.7% actin-binding; 77% PLP-binding) and especially mutant K67E (<1% actin-binding; 100% PLP-binding) are significantly less effective than wt-standard profilins in their ability to inhibit pollen tube growth. PLP also inhibits pollen tube growth. However, PLP is not different from K67E/PLP combined, which has no actin-binding, suggesting that PLP does not function by binding to profilin. In addition, there are differences in the morphology and F-actin organization in cells injected with PLP versus wt-profilin. Whereas wt-profilin causes a fragmentation and marked reduction in the amount of F-actin [L. Vidali et al. (2001) Mol Biol Cell 12:2534–2545], PLP generates an extensive disorganization without any apparent reduction in the amount of F-actin. We conclude that along with actin-binding activity of profilin, PLP-containing proteins also participate in the growth control process, and can do so independently of binding to profilin.Abbreviations 3D Three-dimensional - PLP Poly-l-proline - RMS Root mean square - wt Wild type     

Dynamics of Salmonella enterica and antimicrobial resistance in the Brazilian poultry industry and global impacts on public health

Non-typhoidal Salmonella enterica is a common cause of diarrhoeal disease; in humans, consumption of contaminated poultry meat is believed to be a major source. Brazil is the world’s largest exporter of chicken meat globally, and previous studies have indicated the introduction of Salmonella serovars through imported food products from Brazil. Here we provide an in-depth genomic characterisation and evolutionary analysis to investigate the most prevalent serovars and antimicrobial resistance (AMR) in Brazilian chickens and assess the impact to public health of products contaminated with S. enterica imported into the United Kingdom from Brazil. To do so, we examine 183 Salmonella genomes from chickens in Brazil and 357 genomes from humans, domestic poultry and imported Brazilian poultry products isolated in the United Kingdom. S. enterica serovars Heidelberg and Minnesota were the most prevalent serovars in Brazil and in meat products imported from Brazil into the UK. We extended our analysis to include 1,259 publicly available Salmonella Heidelberg and Salmonella Minnesota genomes for context. The Brazil genomes form clades distinct from global isolates, with temporal analysis suggesting emergence of these Salmonella Heidelberg and Salmonella Minnesota clades in the early 2000s, around the time of the 2003 introduction of the Enteritidis vaccine in Brazilian poultry. Analysis showed genomes within the Salmonella Heidelberg and Salmonella Minnesota clades shared resistance to sulphonamides, tetracyclines and beta-lactams conferred by sul2, tetA and bla_CMY-2 genes, not widely observed in other co-circulating serovars despite similar selection pressures. The sul2 and tetA genes were concomitantly carried on IncC plasmids, whereas bla_CMY-2 was either co-located with the sul2 and tetA genes on IncC plasmids or independently on IncI1 plasmids. Long-term surveillance data collected in the UK showed no increase in the incidence of Salmonella Heidelberg or Salmonella Minnesota in human cases of clinical disease in the UK following the increase of these two serovars in Brazilian poultry. In addition, almost all of the small number of UK-derived genomes which cluster with the Brazilian poultry-derived sequences could either be attributed to human cases with a recent history of foreign travel or were from imported Brazilian food products. These findings indicate that even should Salmonella from imported Brazilian poultry products reach UK consumers, they are very unlikely to be causing disease. No evidence of the Brazilian strains of Salmonella Heidelberg or Salmonella Minnesota were observed in UK domestic chickens. These findings suggest that introduction of the Salmonella Enteritidis vaccine, in addition to increasing antimicrobial use, could have resulted in replacement of salmonellae in Brazilian poultry flocks with serovars that are more drug resistant, but less associated with disease in humans in the UK. The plasmids conferring resistance to beta-lactams, sulphonamides and tetracyclines likely conferred a competitive advantage to the Salmonella Minnesota and Salmonella Heidelberg serovars in this setting of high antimicrobial use, but the apparent lack of transfer to other serovars present in the same setting suggests barriers to horizontal gene transfer that could be exploited in intervention strategies to reduce AMR. The insights obtained reinforce the importance of One Health genomic surveillance.