Microsporogenesis in Brachiaria brizantha (Poaceae) as a selection tool for breeding

The genus Brachiaria comprises more than 100 species and is the single most important genus of forage grass in the tropics. Brachiaria brizantha, widely used in Brazilian pastures for beef and dairy production, is native to tropical Africa. As a subsidy to the breeding program underway in Brazil, cytological studies were employed to determine the chromosome number and to evaluate microsporogenesis in 46 accessions of this species available at Embrapa Beef Cattle (Brazil). Thirty-four accessions presented 2n = 36; seven had 2n = 45, and five had 2n = 54 chromosomes. Based on the higher level of chromosome association observed in diakinesis, in tetra-, penta-, and hexavalents, respectively, it was concluded that they are derived from x = 9; consequently, these accessions are tetra- (2n = 4x = 36), penta- (2n = 5x = 45), and hexaploids (2n = 6x = 54). The most common meiotic abnormalities were irregular chromosome segregation due to polyploidy. Chromosome stickiness, abnormal cytokinesis, non-congressed bivalents in metaphase I and chromosomes in metaphase II, and chromosome elimination were recorded at varying frequencies in several accessions. The mean percentage of meiotic abnormalities ranged from 0.36 to 95.76%. All the abnormalities had the potential to affect pollen viability by generating unbalanced gametes. Among the accessions, only the tetraploid ones with less than 40% of abnormalities are suitable as pollen donors in intra- and interspecific crosses. Currently, accessions with a high level of ploidy (5 and 6n) cannot be used as male genitors in crosses because of the lack of sexual female genitors with the same levels of ploidy.

Detecção dos genes de Staphylococcus aureus, enterotoxinas e de resistência à meticilina em leite

Realizou-se a detecção do gene de Staphylococcus aureus, de enterotoxinas e de resistência à meticilina com extração de DNA feita diretamente de amostras de leite. Das 200 amostras estudadas, 145 (72,5%) amplificaram o gene femA, e estas foram analisadas quanto à presença dos genes sea, seb, sec e mecA. Os genes das enterotoxinas mais prevalentes foram: sea (60%), seb (37,9%) e sec (6,9%). Foram encontradas 18 amostras de leite (11,0 %) com S. aureus portadores do gene mecA. A detecção de S. aureus diretamente do leite, sem a necessidade de isolamento bacteriano e a caracterização do potencial enterotoxigênico, demonstra que a técnica de PCR é muito útil para estudos epidemiológicos das infecções estafilocócicas da glândula mamária. O alto percentual (72,5%) de amostras de leite positivas para a presença do gene femA sugere que S. aureus constitui um dos principais agentes causadores de infecções intramamárias na microrregião de Sete Lagoas-MG e que seu potencial enterotoxigênico e presença do gene mecA, que identifica o S. aureus resistente à meticlina, representa um risco potencial à saúde pública.

BIOLOGIA DE SUPELLA LONGIPALPA (FABRICIUS) (DICTYOPTERA: BLATELLIDAE) EM DIETA ARTIFICIAL E ASSOCIAÇÃO COM MICRO-ORGANISMOS PATOGÊNICOS AO HOMEM

RESUMO Foi estudada a biologia de Supella longipalpa (Fabricius) e seu potencial de contaminação por fungos e bactérias. As coletas foram realizadas em residências localizadas em três bairros: Nossa Senhora das Graças, Betânia e Alvorada na Cidade de Manaus, AM. Foram obtidas 13,6 ninfas por ooteca, com um período de retenção das ootecas no corpo da fêmea de 39,2 horas e intervalo de liberação entre ootecas de 134,4 horas. No estágio ninfal foram obtidos cinco estádios com 68,5% de viabilidade. A razão sexual foi de 49,6 com o período pré-reprodutivo de 6 dias e média de 6,7 ootecas por fêmea. O ciclo total de desenvolvimento foi, em média, de 218,56 dias. Nos estágios ninfal e adulto (macho e fêmea) foi registrada a prevalência de associação com fungos pertencentes aos gêneros Penicillium e Aspergillus e bactérias gram-negativas Enterobacter e Klebsiella prevalecendo nos três bairros analisados.

Divergence of duplicate POMC genes in gilthead sea bream Sparus auratus

Proopiomelanocorticotrophin (POMC) in vertebrates is produced in the pituitary gland and undergoes post-translational processing to give rise to a range of biologically active peptides. Teleosts possess 2-3 different POMC transcripts which have been proposed to have originated from a whole or partial genome duplication. In the present study 2 transcripts of gilthead sea bream POMC (sbPOMC-α1 and α2) were cloned and characterised. sbPOMC-α1 is expressed principally in the melanotroph cells of the pars intermedia (PI) and sbPOMC-α2 is expressed in the corticotroph cells of the rostral pars distalis and probably also in the PI. The 2 sbPOMC transcripts have a differential tissue distribution in extra-pituitary sites. An appraisal of POMC evolution indicates sbPOMCs belong to one of the two main clades that exist in teleosts and that overall a non conservative process of gene loss occurred in this infraclass.

ms17: a meiotic mutation causing partial male sterility in a corn silage hybrid

Cytological analysis under light microscopy of the single hybrid P30R50 of silage corn revealed an abnormal pattern of microsporogenesis that affected the meiotic products. Meiosis progressed normally until diakinesis, but before migration to the metaphase plate, bivalents underwent total desynapsis and 20 univalent chromosomes were scattered in the cytoplasm. At this stage, meiocytes also exhibited a number of chromatin-like fragments scattered throughout the cell. Metaphase I was completely abnormal in the affected cells, and univalent chromosomes and fragments were distributed among several curved spindles. Anaphase I did not occur, and each chromosome or group of chromosomes originated a micronucleus. After this phase, an irregular cytokinesis occurred, and secondary meiocytes with several micronuclei were observed. Metaphase II and anaphase II also did not occur, and after the second cytokinesis, the genomes were fractionated into polyads, generating several unbalanced microspores, with various-sized nuclei. About 35% of the tetrads were abnormal in the hybrid. This spontaneous mutation had been previously reported in a USA maize line called ms17 and was found to cause male sterility.

Host-Pathogen Interactions in Progressive Chronic Periodontitis

Periodontitis is an infection characterized by the occurrence of supporting tissue destruction with an episodic nature. Disease progression is often determined by the loss of attachment level or alveolar bone, and sequential probing of periodontal attachment remains the most commonly utilized method to diagnose progressive destruction of the periodontium. The tolerance method has been the most extensive clinical method used in recent years to determine site-specific attachment level changes. There is abundant evidence that major tissue destruction in periodontal lesions results from the recruitment of immune cells. Considerable effort has been made to study the host cell and mediator profiles involved in the pathogenesis of chronic periodontitis, but the definition of active sites, where current periodontal breakdown occurs, and consecutive characterization of the mediators involved are still among the main concerns. In the present review, we summarize periodontopathic bacteria and host factors, including infiltrating cell populations, cytokines, and host matrix metalloproteinases, associated with under-going episodic attachment loss that could partly explain the mechanisms involved in destruction of the supporting tissues of the tooth.

Meiotic behavior in nonaploid accessions of Brachiaria humidicola (Poaceae) and implications for breeding

Brachiaria humidicola is a grass adapted to seasonally swampy grasslands in Africa; two cultivars, 'common' and Llanero, are widely used in Brazilian pastures. New cultivars are in great demand in order to diversify current production systems to achieve improved quality and yield. Cytological analyses of 55 accessions of this species available from the Embrapa Beef Cattle germplasm collection revealed that 27 are apomictic and have 2n = 54 chromosomes. Chromosome pairing as bi- to nonavalent associations at diakinesis indicated a basic chromosome number in this species of x = 6, as found in other closely related Brachiaria species. Thus, these 27 accessions are nonaploid (2n = 9x = 54). Abnormalities were found in the meiosis of these accessions, at variable frequencies. The most common abnormalities were those related to irregular chromosome segregation, which led to unbalanced gamete formation; but chromosome stickiness, cell fusion, and absence of cytokinesis were also recorded. Although some accessions have a low frequency of meiotic abnormalities, ensuring potentially good pollen viability, these cannot be used in hybridization due to a lack of sexual accessions with the same ploidy level.

Imaging of the ovine corpus luteum microcirculation with contrast ultrasound

Ultrasound contrast agents have been the subject of microvascular imaging research. The sheep corpus luteum (CL) is a microvascular tissue that provides a natural angiogenic and antiangiogenic process, which changes during the luteal phase of the estrous cycle of the ewe. It can also be controlled and monitored endocrinologically, providing a very attractive in vivo model for the study and development of microvascular measurement. The perfusion of the fully developed CL between days 8 and 12 of the estrous cycle was studied in six ewes. A Philips iU22 ultrasound scanner (Bothell, WA, USA) with the linear array probe L9-3 was used to capture contrast-enhanced images after an intravenous bolus injection of 2.4 mL SonoVue (Bracco S.P.A., Milan, Italy). Time-intensity curves of a region of interest inside the CL were formed from linearized image data. A lagged-normal model to simulate the compartmental kinetics of the microvascular flow was used to fit the data, and the wash-in time was measured. Good contrast enhancement was observed in the CLs of all animals and the wash-in time averaged at 5.5 s with 9% uncertainty. The regression coefficient was highly significant for all fits. These data correlated with stained endothelial area in the histology performed postmortem. Two ewes were injected with prostaglandin F2alpha to induce CL regression, which resulted in an increase of wash-in time after a few hours. The CL of the ewe is thus proposed as an ideal model for the study and development of microvascular measurements using contrast ultrasound. Our initial results demonstrate a highly reproducible model for the study of the microvascular hemodynamics in a range of tissues and organs.

Expression of the myosin light chains 1, 2 and 3 in the muscle of blackspot seabream (Pagellus bogaraveo, Brunnich), during development

Previous studies on the histochemistry and immunoreactivity of fibres in lateral muscle of blackspot seabream indicated that there is a developmental transition in the composition of myofibrillar proteins, which presumably reflects changes in contractile function as the fish grows. We hypothesize that the phenomenon underscores age and spatial differences in the expression of myosin light chains (MLC), not studied yet in this species. In this study, we examined selected stages in the post-hatching development of the muscle of blackspot seabream: hatching (0 days), mouth opening (5 days), weaning (40 days) and juveniles (70 days). The spatial expression of embryonic MLC 1 (MLC1), 2 (MLC2) and 3 (MLC3) was studied by in situ hybridization. Overall, MLC expression patterns were overlapping and restricted to the fast muscle. At hatching and mouth opening, all MLC types were highly expressed throughout the musculature in fast muscle. The expression levels in fast muscle remained high until weaning when germinal zones appeared on the dorsal and ventral areas. The germinal zones were characterized by small-diameter fast fibres with high levels of MLC expression. This pattern persisted up to day 70, when the germinal zones disappeared and expression of MLCs was observed only in the smaller cells of the fast muscle mosaic. These results support our hypothesis and, together with previous imuno- and histochemistry results, allow a better understanding of the mechanism of muscle differentiation and growth in fish beyond larval stages, and form- the basis for further comparative and experimental studies with this economically relevant species.

Efeito protetor das frações proteicas do soro de leite em camundongos Balb/C infectados por Escherichia coli O157: H7

Avaliou-se o efeito protetor das frações proteicas do soro do leite sobre as vilosidades intestinais de camundongos Balb/C, fêmeas, infectadas por Escherichia coli O157:H7. Foram utilizados 48 animais, distribuídos aleatoriamente em oito grupos de seis fêmeas cada um. Os animais dos grupos 1 e 2 (controles) receberam dieta AIN93G padrão; os dos grupos 3 e 4, AIN93G + alfalactalbumina; os dos grupos 5 e 6, AIN93G + betalactoglobulina e os dos grupos 7 e 8, AIN93G + concentrado proteico total e água ad libitum por sete dias. No dia zero, os animais dos grupos 2, 4, 6 e 8 foram inoculados, por meio de cânula de gavagem, com 0,5mL de E. coli O157:H7, na concentração de 7 x 10(10)UFC/mL. Os animais foram acompanhados clinicamente e sacrificados, no oitavo dia experimental. Verificou-se, por meio de exames histológicos e da morfometria, que as frações betalactoglobulina e alfalactalbumina exerceram efeito protetor sobre as vilosidades intestinais do jejuno distal e do íleo (P<0,05), respectivamente. O concentrado proteico total não demonstrou efeito protetor sobre as vilosidades intestinais.

Distribution of killer cell immunoglobulin-like receptor genes in the mestizo population from Venezuela

This study represents the first report on the distribution of KIR genes in 205 unrelated healthy mestizo Venezuelan individuals. Genotyping analysis showed that all KIR genes are present in this population. Frequency of inhibitory killer cell immunoglobulin-like receptors (KIRs) exceeded 0.69, except for KIR2DL2 (0.29) and 2DL5 (0.37). Activating KIRs showed low frequencies (0.11-0.29), except for KIR2DS4 (0.68). Forty-five different KIR genotypes were identified, with a predominance of three genotypes found in 50.7% of the population of which 25.9% were individuals homozygous for haplotype A. The frequencies of KIR genes reflect the ethnic admixture existing in the mestizo Venezuelan population.

Etiology of bronchiolitis in a hospitalized pediatric population: prospective multicenter study

Background

In 2006, bronchiolitis due to adenovirus nosocomial infections resulted in the closure of a pediatric department in northern Portugal.

Objectives

To determine the etiology of bronchiolitis in northern Portugal.

Study design

It was a prospective multicenter study on the etiology of bronchiolitis during the respiratory syncytial virus (RSV) season (November–April). Children ≤24 months of age admitted for a first wheezing episode were included. Nasopharyngeal specimens were analyzed by an indirect immunofluorescent-antibody assay (IFA) for RSV, adenovirus (HAdV), parainfluenza (PIV) 1–3 and influenza (IV) A and B and by polymerase chain reaction (PCR) or reverse transcription-PCR for the same viruses and for human metapneumovirus (hMPV), bocavirus (HBoV), rhinovirus (HRV), coronaviruses (229/E; NL63; OC43; HKU1) and enterovirus.

Results

During this period, 253 children were included, 249 IFA analyses and 207 PCRs were performed. IFA detected RSV in 58.1%; PCR increased it to 66.7%. IFA detected HAdV in 3.2%, PCR 10.0%. PCR detected IV A in 5; IV B in 2; PIV 1 in 6, PIV 2 in 4 and PIV 3 in 11 cases. HBoV, as single agent in 2 cases, and HRV were positive in 8 samples and hMPV in 11. With this virus panel, 19.7% remained without etiology.

Conclusions

The most frequent agent was RSV, followed by HAdV. PCR can be cost-effective and more accurate than IFA, which is crucial for HAdV that may be associated with significant mortality (IFA alone did not detect 2/3 of the cases).

Identification and dynamics of a cryptic suture zone in tropical rainforest

Suture zones, shared regions of secondary contact between long-isolated lineages, are natural laboratories for studying divergence and speciation. For tropical rainforest, the existence of suture zones and their significance for speciation has been controversial. Using comparative phylogeographic evidence, we locate a morphologically cryptic suture zone in the Australian Wet Tropics rainforest. Fourteen out of 18 contacts involve morphologically cryptic phylogeographic lineages, with mtDNA sequence divergences ranging from 2 to 15 per cent. Contact zones are significantly clustered in a suture zone located between two major Quaternary refugia. Within this area, there is a trend for secondary contacts to occur in regions with low environmental suitability relative to both adjacent refugia and, by inference, the parental lineages. The extent and form of reproductive isolation among interacting lineages varies across species, ranging from random admixture to speciation, in one case via reinforcement. Comparative phylogeographic studies, combined with environmental analysis at a fine-scale and across varying climates, can generate new insights into suture zone formation and to diversification processes in species-rich tropical rainforests. As arenas for evolutionary experimentation, suture zones merit special attention for conservation.

Determinação do perfil protéico da membrana externa da Leptospira interrogans sorovariedade Hardjoprajitno

Estudou-se o perfil das proteínas da membrana externa (PME) da Leptospira interrogans sorovariedade Hardjoprajitno por meio da eletroforese bidimensional. Foram utilizadas técnicas de extração das PME com Triton x114 e precipitação com acetona. Os géis foram corados com nitrato de prata e as imagens analisadas para determinação da massa molecular das proteínas detectadas. Foram visualizadas 35 bandas protéicas, sendo que cinco delas se destacaram por estarem em maior quantidade: 22,54KDa (LipL22), 30/26KDa (LipL32), 34,41KDa (PME34), 42,75KDa (LipL41) e 58,59KDa (LipL63).