Estimativas de herdabilidade para idade ao primeiro parto de novilhas da raça Nelore

Estimaram-se parâmetros genéticos para idade ao primeiro parto (IPP) de, aproximadamente, 6.000 novilhas, utilizando-se três diferentes definições de grupo contemporâneo (GC). Foram considerados no modelo o efeito aleatório de animal e os efeitos fixos de GC, além dos efeitos linear e quadrático da idade da mãe da novilha ao parto (IDV). A primeira definição de grupo contemporâneo (GC1) considerou as variáveis fazenda, ano, estação de nascimento, grupo de manejo de nascimento, desmama e sobreano e tipo de serviço (monta natural, monta controlada ou inseminação artificial). A segunda definição de grupo contemporâneo (GC2) incluiu as mesmas variáveis de GC1, além de ano e estação do parto. A terceira definição de grupo contemporâneo considerou as variáveis ano e estação de nascimento, fazenda, ano e estação do parto e tipo de cobertura. As estimativas de herdabilidade para IPP foram de 0,16 ± 0,03, 0,09 ± 0,03 e 0,11 ± 0,02, considerando-se GC1, GC2 e GC3, respectivamente.

Genetic and physiological alterations occurring in a yeast population continuously propagated at increasing temperatures with cell recycling

This work investigated the effects of increasing temperature from 30 degrees C to 47 degrees C on the physiological and genetic characteristics of Saccharomyces cerevisiae strain 63M after continuous fermentation with cell recycling in a system of five reactors in series. Steady state was attained at 30 degrees C, and then the temperature of the system was raised so it ranged from 35 degrees C in the last reactor to 43 degrees C in the first reactor or feeding reactor with a 2 degrees C difference between reactors. After 15 days at steady state, the temperature was raised from 37 degrees C to 45 degrees C for 25 days at steady state, then from 39 degrees C to 47 degrees C for 20 days at steady state. Starter strain 63M was a hybrid strain constructed to have a MAT a/alpha, LYS/lys, URA/ura genotype. This hybrid yeast showed vigorous growth on plates at 40 degrees C, weak growth at 41 degrees C, positive assimilation of melibiose, positive fermentation of galactose, raffinose and sucrose. of 156 isolates obtained from this system at the end of the fermentation process, only 17.3% showed the same characteristics as starter strain 63M. Alterations in mating type reaction and in utilization of raffinose, melibiose, and sucrose were identified. Only 1.9% of the isolates lost the ability to grow at 40 degrees C. Isolates showing requirements for lysine and uracil were also obtained. In addition, cell survival was observed at 39-47 degrees C, but no isolates showing growth above 41 degrees C were obtained.

The plant energy-dissipating mitochondrial systems: Depicting the genomic structure and the expression profiles of the gene families of uncoupling protein and alternative oxidase in monocots and dicots

The simultaneous existence of alternative oxidases and uncoupling proteins in plants has raised the question as to why plants need two energy-dissipating systems with apparently similar physiological functions. A probably complete plant uncoupling protein gene family is described and the expression profiles of this family compared with the multigene family of alternative oxidases in Arabidopsis thaliana and sugarcane (Saccharum sp.) employed as dicot and monocot models, respectively. In total, six uncoupling protein genes, AtPUMP1-6, were recognized within the Arabidopsis genome and five (SsPUMP1-5) in a sugarcane EST database. The recombinant AtPUMP5 protein displayed similar biochemical properties as AtPUMP1. Sugarcane possessed four Arabidopsis AOx1-type orthologues (SsAOx1a-1d); no sugarcane orthologue corresponding to Arabidopsis AOx2-type genes was identified. Phylogenetic and expression analyses suggested that AtAOx1d does not belong to the AOx1-type family but forms a new (AOx3-type) family. Tissue-enriched expression profiling revealed that uncoupling protein genes were expressed more ubiquitously than the alternative oxidase genes. Distinct expression patterns among gene family members were observed between monocots and dicots and during chilling stress. These findings suggest that the members of each energy-dissipating system are subject to different cell or tissue/organ transcriptional regulation. As a result, plants may respond more flexibly to adverse biotic and abiotic conditions, in which oxidative stress is involved. © The Author [2006]. Published by Oxford University Press [on behalf of the Society for Experimental Biology]. All rights reserved.

Frequency and genetic diversity of the MAT1 locus of Histoplasma capsulatum isolates in Mexico and Brazil

The MAT1-1 and MAT1-2 idiomorphs associated with the MAT1 locus of Histoplasma capsulatum were identified by PCR. A total of 28 fungal isolates, 6 isolates from human clinical samples and 22 isolates from environmental (infected bat and contaminated soil) samples, were studied. Among the 14 isolates from Mexico, 71.4% (95% confidence interval [95% CI], 48.3% to 94.5%) were of the MAT1-2 genotype, whereas 100% of the isolates from Brazil were of the MAT1-1 genotype. Each MAT1 idiomorphic region was sequenced and aligned, using the sequences of the G-217B (+mating type) and G-186AR (-mating type) strains as references. BLASTn analyses of the MAT1-1 and MAT1-2 sequences studied correlated with their respective+ and-mating type genotypes. Trees were generated by the maximum likelihood (ML) method to search for similarity among isolates of each MAT1 idiomorph. All MAT1-1 isolates originated from Brazilian bats formed a well-defined group; three isolates from Mexico, the G-217B strain, and a subgroup encompassing all soil-derived isolates and two clinical isolates from Brazil formed a second group; last, one isolate (EH-696P) from a migratory bat captured in Mexico formed a third group of the MAT1-1 genotype. The MAT1-2 idiomorph formed two groups, one of which included two H. capsulatum isolates from infected bats that were closely related to the G-186AR strain. The other group was formed by two human isolates and six isolates from infected bats. Concatenated ML trees, with internal transcribed spacer 1 (ITS1) -5.8S-ITS2 and MAT1-1 or MAT1-2 sequences, support the relatedness of MAT1-1 or MAT1-2 isolates. H. capsulatum mating types were associated with the geographical origin of the isolates, and all isolates from Brazil correlated with their environmental sources. © 2013, American Society for Microbiology. All Rights Reserved.

Cryptococcus neoformans de fontes ambientais e biopropecção de extratos de plantas com atividade saneante

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fisiologia, patogenicidade, sensibilidade a fungicidas e caracterização molecular de Phytophthora capsici Leonian do pimentão (Capsicum annuum L.)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Population Structure and Pathotype Diversity of the Wheat Blast Pathogen Magnaporthe oryzae 25 Years After Its Emergence in Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The roles of UPF3a and UPF3b in nonsense mediated decay

Nonsense-mediated decay (NMD) degrades aberrant transcripts containing premature termination codons (PTCs). The T-cell receptor (TCR) locus undergoes error-prone rearrangements that frequently acquire PTCs. Transcripts harboring PTCs from this locus are downregulated much more than transcripts from non-rearranging genes. Efficient splicing is essential for this robust downregulation. ^ Here I show that TCR NMD is unique in another respect: it is not impaired by RNAi-mediated depletion of the NMD factor UPF3b. This differentiates TCR transcripts from classical NMD (assayed using β-globin or triose phosphate isomerase transcripts), which does depend on UPF3b. Depletion of UPF3a, which encodes a gene related to UPF3b, also had no effect on TCR NMD. Mapping experiments identified TCR sequences that when deleted or mutated caused a switch to UPF3b dependence. Since UPF3b dependence was invariably accompanied by less efficient RNA splicing, this suggests that UPF3b-dependent NMD occurs when transcripts are generated by inefficient splicing. Microarray analysis revealed the existence of many NMD-targeted mRNAs from wild-type genes whose downregulation is impervious to UPF3b depletion. This suggests the existence of an alternative NMD pathway independent of UPF3b that is widely used to downregulate the level of both normal and mutant transcripts. ^ During the course of my studies, I also found that the function of UPF3a is fundamentally distinct from that of UPF3b in several aspects. First, classical NMD failed to be impaired by UPF3a depletion, whereas it was reversed by UPF3b depletion. Second, UPF3a depletion had no effect on NMD elicited by tethered UPF2, whereas UPF3b depletion blocked this response. Thus, UPF3a does not function in classical NMD. Third, UPF3b depletion upregulated the expression of UPF3a, whereas UPF3a depletion had no effect on UPF3b expression. This suggests that a UPF3b-mediated feedback network exists that regulates the UPF3a expression. Lastly, UPF3a depletion but not UPF3b depletion significantly upregulated TCR precursor RNAs. This suggests that UPF3a, not UPF3b, functions in the surveillance of precursor RNAs, which typically contain many PTCs in the introns. Collectively, my data suggests that UPF3a and UPF3b are not functionally redundant, as previously thought, but instead have separable functions. ^

Strong balancing selection at HLA loci: Evidence from segregation in South Amerindian families

The genotypic proportions for major histocompatibility complex loci, HLA-A and HLA-B, of progeny in families in 23 South Amerindian tribes in which segregation for homozygotes and heterozygotes could occur are examined. Overall, there is a large deficiency of homozygotes compared with Mendelian expectations (for HLA-A, 114 observed and 155.50 expected and for HLA-B 110 observed and 144.75 expected), consistent with strong balancing selection favoring heterozygotes. There is no evidence that these deficiencies were associated with particular alleles or with the age of the individuals sampled. When these families were divided into four mating types, there was strong selection against homozygotes, averaging 0.462 for three of the mating types over the two loci. For the other mating type in which the female parent is homozygous and shares one allele with the heterozygous male parent, there was no evidence of selection against homozygotes. A theoretical model incorporating these findings surprisingly does not result in a stable polymorphism for two alleles but does result in an excess of heterozygotes and a minimum fitness at intermediate allele frequencies. However, for more than two alleles, balancing selection does occur and the model approaches the qualities of the symmetrical heterozygote advantage model as the number of alleles increases.

The Cell Surface Flocculin Flo11 Is Required for Pseudohyphae Formation and Invasion by Saccharomyces cerevisiae

Diploid yeast develop pseudohyphae in response to nitrogen starvation, while haploid yeast produce invasive filaments which penetrate the agar in rich medium. We have identified a gene, FLO11, that encodes a cell wall protein which is critically required for both invasion and pseudohyphae formation in response to nitrogen starvation. FLO11 encodes a cell surface flocculin with a structure similar to the class of yeast serine/threonine-rich GPI-anchored cell wall proteins. Cells of the Saccharomyces cerevisiae strain Σ1278b with deletions of FLO11 do not form pseudohyphae as diploids nor invade agar as haploids. In rich media, FLO11 is regulated by mating type; it is expressed in haploid cells but not in diploids. Upon transfer to nitrogen starvation media, however, FLO11 transcripts accumulate in diploid cells, but not in haploids. Overexpression of FLO11 in diploid cells, which are otherwise not invasive, enables them to invade agar. Thus, the mating type repression of FLO11 in diploids grown in rich media suffices to explain the inability of these cells to invade. The promoter of FLO11 contains a consensus binding sequence for Ste12p and Tec1p, proteins known to cooperatively activate transcription of Ty1 elements and the TEC1 gene during development of pseudohyphae. Yeast with a deletion of STE12 does not express FLO11 transcripts, indicating that STE12 is required for FLO11 expression. These ste12-deletion strains also do not invade agar. However, the ability to invade can be restored by overexpressing FLO11. Activation of FLO11 may thus be the primary means by which Ste12p and Tec1p cause invasive growth.

The Conserved Core of a Human SIR2 Homologue Functions in Yeast Silencing

Silencing is a universal form of transcriptional regulation in which regions of the genome are reversibly inactivated by changes in chromatin structure. Sir2 (Silent Information Regulator) protein is unique among the silencing factors in Saccharomyces cerevisiae because it silences the rDNA as well as the silent mating-type loci and telomeres. Discovery of a gene family of Homologues of Sir Two (HSTs) in organisms from bacteria to humans suggests that SIR2’s silencing mechanism might be conserved. The Sir2 and Hst proteins share a core domain, which includes two diagnostic sequence motifs of unknown function as well as four cysteines of a putative zinc finger. We demonstrate by mutational analyses that the conserved core and each of its motifs are essential for Sir2p silencing. Chimeras between Sir2p and a human Sir2 homologue (hSir2Ap) indicate that this human protein’s core can substitute for that of Sir2p, implicating the core as a silencing domain. Immunofluorescence studies reveal partially disrupted localization, accounting for the yeast–human chimeras’ ability to function at only a subset of Sir2p’s target loci. Together, these results support a model for the involvement of distinct Sir2p-containing complexes in HM/telomeric and rDNA silencing and that HST family members, including the widely expressed hSir2A, may perform evolutionarily conserved functions.

Significant competitive advantage conferred by meiosis and syngamy in the yeast Saccharomyces cerevisiae.

The presumed advantages of genetic recombinations are difficult to demonstrate directly. To investigate the effects of recombination and background heterozygosity on competitive ability, we have performed serial-transfer competition experiments between isogenic sexual and asexual strains of the yeast Saccharomyces cerevisiae. The members of these diploid pairs of strains differed only in being heterozygous (sexual) or homozygous (asexual) at the mating type or MAT locus. Competing pairs had either a completely homozygous or a heterozygous genetic background, the latter being heterozygous at many different loci throughout the genome. A round of meiotic recombination (automixis) conferred a large and statistically significant enhancement of competitive ability on sexual strains with a heterozygous genetic background. By contrast, in homozygous background competitions, meiosis decreased the sexual strains' initial relative competitive ability. In all cases, however, the sexual strains outcompeted their isogenic asexual counterparts, whether meiotic recombination had occurred or not. In some genetic backgrounds, this was due in part to an overdominance effect on competitive advantage of heterozygosity at the MAT locus. The advantage of the sexual strains also increased significantly during the course of the homozygous background competitions, particularly when meiosis had occurred. This latter effect either did not occur or was very weak in heterozygous background competitions. Overall, sexual strains with heterozygous genetic backgrounds had a significantly higher initial relative competitive ability than those with homozygous backgrounds. The advantage of mating type heterozygosity in this organism extends far beyond the ability to recombine meiotically.

(Table 2) Rate of reduction in cell size (apical length) and growth rate for seven Fragilariopsis kerguelensis strains sampled during POLARSTERN cruise ANT-XXI/3

The planktonic diatom Fragilariopsis kerguelensis plays an important role in the biogeochemical cycles of the Southern Ocean, where remains of its frustules form the largest deposit of biogenic silica anywhere in the world. We assessed the genetic identity of 26 strains, from cells collected at various sites in the Southern Ocean, using three molecular markers, LSU and ITS rDNA and rbcL. The LSU sequences were identical among the tested strains, ITS sequences were highly similar, and only one base pair difference was detected among the rbcL sequences. These results, together with a large number of successful mating experiments demonstrated that the strains belong to a single biological species. We investigated the mating system and life cycle traits of F. kerguelensis. Cell size diminished gradually in clonal strains. Gamete formation only occurred when strains of opposite mating type - within a cell size range of 7-36 µm - were mixed together. Two binucleate gametes were formed in each gametangium and gamete conjugation produced a zygote that had four nuclei and was surrounded by thin siliceous scales. Two out of the four nuclei subsequently degenerated and the zygote expanded to form an auxospore surrounded by a transverse and a longitudinal perizonium. Staining with the fluorochrome PDMPO provided for the first time a clear demonstration that the longitudinal perizonium is formed after auxospore expansion is complete. Initial cells produced within the mature auxospores were 78-101 µm in length. Various authors have shown that the average valve size of F. kerguelensis varies in sediment samples collected in regions and seasons with different primary production regimes and this parameter has thus been proposed as a biological proxy for palaeo-productivity. A better understanding of the life cycle of F. kerguelensis should help the design of future investigations aimed at testing the link between cell size distribution in the natural environment and the role that environmental factors might have in the regulation of population cell size.

Primers específicos para a determinação de MAT-1 em Fusarium decemcellulare.

Fusarium decemcellulare é caracterizado por ser endófito ou patogênico a diversas plantas em regiões tropicais e subtropicais. Em guaranazeiro é o agente causal de superbrotamento um dos principais problemas da cultura. O estudo do sistema mating type, idiomorfos MAT-1 e MAT-2, além de fornecer uma compreensão detalhada para delimitar espécies dentro de complexos de espécies, é fundamental para estudo da dinâmica e do potencial de variação genética de um patógeno. Primers degenerados disponíveis na literatura para determinar mating type em várias espécies de Fusarium, não foi capaz de amplificar o MAT-1 em Fdc. Assim, este trabalho teve como objetivo desenvolver primers específicos para determinar MAT-1 em F. decemcellulare. Inicialmente primers degenerados foram desenhados com base nas sequencias do MAT-1 disponíveis no NCBI, amplificado em Fdc e o fragmento do tamanho esperado foi clonado e sequenciado para o desenho de iniciadores específicos que foram validados usando população de isolados de Fdc de diferentes locais de coleta.

Synthesis of stocks and phenotypic effects of dwarf and bantam sex-linked major genes in egg-type chickens

The present study describes the production of stocks segregating dwarf (dw), bantam (dwB) and normal (dw+) alleles, as well as the characters, shank length, adult body weight, age at sexual maturity and egg production. Heterozygous K dw+/k dwB sires were mated to normal (dw+) dams to produce stock D6.a, and mated to dwB females to produce stock D6.b. Stock D4.a came from mating F1 heterozygous dwB dw sires to dwarf Leghorns. In a third series of matings, 7/8 Sebright and 1/8 dw-Leghorn dwB dw sires were crossed to three groups of dams of different genotypes. The progeny of the normal (dw+), dwarf (dw), and bantam (dwB) dams were designated as stocks D4.b, D4.c and D4.d, respectively. The dw+ dams were White Leghorn strain cross females. The difference between the rate of laying of normal (69.7%) and their bantam sisters (68.6%) was not statistically significant when the average 32-week body weight of the dw+ sisters was 1,897 g. However, when the 32-week body weight of the normal daughters from the same sires and smaller dams was around 1,646 g, the difference between the rate of laying of the normal (78.1%) and their bantam sisters (75.9%) was significant (P < 0.05). The dwB gene may have a similar but smaller effect on the rate of egg laying than its dwarf allele. The difference between sexual maturity of normal and bantam daughters of either the largest or the smallest dams was not statistically significant, even though the smallest dwB pullets were in average 2.9 days older at first egg. The use of shank length combined with adult body weight allowed a precise discrimination between bantams and dwarfs