Two-Way Selection for Daily Gain and Feed Conversion in a Composite Rabbit Population

We conducted a two-way selection experiment in a composite rabbit population to investigate the responses to selection for postweaning ADG and feed conversion (FC). Two generations of crossing, followed by four generations of random pair matings, preceded three generations of selection. Selection was practiced within four lines: high-feed conversion (HFC), low-feed conversion (LFC), high gain (HG), and low gain (LG). Data on 1,446 rabbits from the random mating and selection generations were fitted to an animal model to estimate heritabilities of and the genetic correlation between ADG and FC. The two-trait model included rabbit and common litter random effects and line, generation, and sex fixed effects. Estimates of heritability of ADG and FC were .48 and .29, respectively, and the genetic correlation between them was -.82. Common litter environmental effects accounted for a proportion of .11 and . 13 of the phenotypic variation of the two traits, respectively. For ADG (in g/d) the regressions of mean breeding values on generation number during the selection period were 1.23 ± .12 (P < .01) in the HG line and -.86 ± .12 (P < .01) in the LG line; the regressions for FC (in g feed/g gain) were -.07 ± .01 (P < .01) in the HFC line and .03 ± .01 (P < .05) in the LFC line. Selection for ADG was effective in improving ADG and FC.

Distinct regions of loss of heterozygosity on 22q at different sites of head and neck squamous cell carcinomas

Background: Frequent loss of heterozygosity (LOH) has been reported in many types of cancer, including head and neck carcinomas. Somatic deletions involving specific chromosomal regions are strongly associated with inactivation of the allele of a tumor suppressor gene located within the deleted region. In most studies concerning LOH in head and neck squamous cell carcinomas (HNSCC) the different anatomical sites are not distinguished. The behavior of tumors arising at various sites differs significantly, however, suggesting different intrinsic tumor properties. In this study we compared the LOH on 22q and its relationship to clinicopathological parameters at the three major sites of HNSCC: oral cavity, larynx and pharynx. Material/Methods: LOH and microsatellite instability (MSI) were studied using seven polymorphic microsatellite markers mapped to the 22q11-q13.3 region in 37 oral, 32 laryngeal, and 31 pharyngeal carcinomas. Results: Two separate regions of LOH were identified in the laryngeal (22q11.2-12.1) and oral cavity (22q13.1-13.31) tumors. When the different anatomical sites were compared, a statistically significant difference was found between the presence of LOH at D22S421 (p<0.001), D22S315 (p=0.014) and D22S929 (p=0.026) in the laryngeal tumors. Conclusions: These data suggest that distinct regions on 22q are involved in LOH in oral cavity and laryngeal tumorigenesis but do not support a similar association between the development of pharyngeal tumors and genes located on 22q. These findings implicate the presence of different tumor suppressor genes mapping to distinct regions on chromosome 22q in oral and laryngeal carcinomas.

Description of electrophoretic and chromatographic hemoglobin profile of Rhinoclemmys punctularia

Studies of the hemoglobin pattern in Brazilian reptiles are important for determining ecological and phylogenetic relationships, but they are scarce. Peripheral blood samples were obtained from 7 males and 18 females of Rhinoclemmys punctularia. The hematological profile was based on the total hemoglobin and hematocrit values. The hemoglobin profile was obtained using electrophoretic procedures at different pH, isoelectric focusing, globin chain electrophoresis, and HPLC. The hematocrit (31 ± 2%) and total hemoglobin (7.5 ± 0.2 g/dL) values did not indicate gender variations. Alkaline pH electrophoresis of the total blood samples treated with 1% saponin demonstrated the presence of four well-defined hemoglobin fractions, one major component (fraction I), showing cathodic migration and three others faster than fraction I with anodic migration. When the samples were precipitated with chloroform, only two hemoglobin fractions were observed, similar to fractions I and III from the first procedure. Isoelectric focusing and HPLC showed the same pattern. With acid and neutral pH electrophoresis, two fractions with anodic migration were observed. The globin chain identification at alkaline pH showed two fractions, but four fractions were observed at acidic pH, suggesting that different polypeptide chains are involved in the hemoglobin molecule. The chromatographic separation of the total blood sample demonstrated that the major fraction comprised 81.9% and the minor 18.1%. The results obtained demonstrated a similarity between these hemoglobin components and those of some Chelidae reported in the literature for both land and aquatic animals, reflecting the adaptation to environmental conditions. ©FUNPEC-RP.

Heteropicnotic chromatin and nucleolar activity in meiosis and spermiogenesis of Limnogonus aduncus (Heteroptera, Gerridae): a stained nucleolar organizing region that can serve as a model for studying chromosome behavior.

Males of Limnogonus aduncus were found to have the sex chromosome system X0 and chromosome number 2n = 23 (22A + X0). Testis cells were stained with lacto-acetic orcein and silver nitrate so that changes in the morphology and degree of staining of the heteropicnotic chromatin and the nucleolar material could be observed during meiosis and spermiogenesis. These structures share the same nuclear position and could be seen until almost the end of spermiogenesis. A chromosome region stained with silver nitrate was indicative of a nucleolar organizing region (NOR), which is rarely detected in Heteroptera with this technique. The NOR is located at one end of a single member of an autosome pair. The finding of this stained region enabled us to observe that the telomeric association of sister chromatids that characterizes the Heteroptera does not include the chromosome ends, where NORs are located; we also observed in anaphase that the chromosome end through which it is pulled to the pole is the one containing the NOR. Another observation was that the single nucleolar body present in the cells at anaphase never goes to the cell pole that does not receive the NOR. We conclude that L. aduncus is a good model for cytogenetic studies involving nucleolar activity and also may be useful for studying the mechanisms of activation and inactivation of kinetic activity at the chromosome ends. Although the chromosomes of Heteroptera are known to be holocentric, whether kinetic activity is restricted to one or involves both chromosome ends is still not well understood.

MODY 2: Mutation identification and molecular ancestry in a Brazilian family

Maturity Onset Diabetes of the Young (MODY) is a heterogeneous group of genetic diseases characterized by a primary defect in insulin secretion and hyperglycemia, non-ketotic disease, monogenic autosomal dominant mode of inheritance, age at onset less than 25. years, and lack of auto-antibodies. It accounts for 2-5% of all cases of non-type 1 diabetes. MODY subtype 2 is caused by mutations in the glucokinase (GCK) gene. In this study, we sequenced the GCK gene of two volunteers with clinical diagnosis for MODY2 and we were able to identify four mutations including one for a premature stop codon (c.76C>T). Based on these results, we have developed a specific PCR-RFLP assay to detect this mutation and tested 122 related volunteers from the same family. This mutation in the GCK gene was detected in 21 additional subjects who also had the clinical features of this genetic disease. In conclusion, we identified new GCK gene mutations in a Brazilian family of Italian descendance, with one due to a premature stop codon located in the second exon of the gene. We also developed a specific assay that is fast, cheap and reliable to detect this mutation. Finally, we built a molecular ancestry model based on our results for the migration of individuals carrying this genetic mutation from Northern Italy to Brazil. © 2012 Elsevier B.V.

Phenotypic plasticity of composite beef cattle performance using reaction norms model with unknown covariate

The objective of the present study was to determine the presence of genotype by environment interaction (G × E) and to characterize the phenotypic plasticity of birth weight (BW), weaning weight (WW), postweaning weight gain (PWG) and yearling scrotal circumference (SC) in composite beef cattle using the reaction norms model with unknown covariate. The animals were born between 1995 and 2008 on 33 farms located throughout all Brazilian biomes between latitude -7 and -31, longitude -40 and -63. The contemporary group was chosen as the environmental descriptor, that is, the environmental covariate of the reaction norms. In general, higher estimates of direct heritability were observed in extreme favorable environments. The mean of direct heritability across the environmental gradient ranged from 0.05 to 0.51, 0.09 to 0.43, 0.01 to 0.43 and from 0.12 to 0.26 for BW, WW, PWG and SC, respectively. The variation in direct heritability observed indicates a different response to selection according to the environment in which the animals of the population are evaluated. The correlation between the level and slope of the reaction norm for BW and PWG was high, indicating that animals with higher average breeding values responded better to improvement in environmental conditions, a fact characterizing a scale of G × E. Low correlation between the intercept and slope was obtained for WW and SC, implying re-ranking of animals in different environments. Genetic variation exists in the sensitivity of animals to the environment, a fact that permits the selection of more plastic or robust genotypes in the population studied. Thus, the G × E is an important factor that should be considered in the genetic evaluation of the present population of composite beef cattle. © The Animal Consortium 2012.

Cooperative RNA Polymerase Molecules Behavior on a Stochastic Sequence-Dependent Model for Transcription Elongation

The transcription process is crucial to life and the enzyme RNA polymerase (RNAP) is the major component of the transcription machinery. The development of single-molecule techniques, such as magnetic and optical tweezers, atomic-force microscopy and single-molecule fluorescence, increased our understanding of the transcription process and complements traditional biochemical studies. Based on these studies, theoretical models have been proposed to explain and predict the kinetics of the RNAP during the polymerization, highlighting the results achieved by models based on the thermodynamic stability of the transcription elongation complex. However, experiments showed that if more than one RNAP initiates from the same promoter, the transcription behavior slightly changes and new phenomenona are observed. We proposed and implemented a theoretical model that considers collisions between RNAPs and predicts their cooperative behavior during multi-round transcription generalizing the Bai et al. stochastic sequence-dependent model. In our approach, collisions between elongating enzymes modify their transcription rate values. We performed the simulations in Mathematica® and compared the results of the single and the multiple-molecule transcription with experimental results and other theoretical models. Our multi-round approach can recover several expected behaviors, showing that the transcription process for the studied sequences can be accelerated up to 48% when collisions are allowed: the dwell times on pause sites are reduced as well as the distance that the RNAPs backtracked from backtracking sites. © 2013 Costa et al.

Estudo de modelos não-lineares na descrição do crescimento de fêmeas da raça Canchim

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ajuste de modelos não lineares e estimativas de parâmetros genéticos para produção de ovos de uma linhagem de poedeiras White Leghorn

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo genético quantitativo do fluxo lácteo em bovinos da raça Holandesa

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modelagem das trajetórias médias do peso vivo e do rendimento de carcaça de tilápias do Nilo (Oreochromis niloticus) por meio de funções B-spline

Employing the method of least squares and quadratic B-spline polynomials, different statistical models were tested to identify the most appropriate to model the mean trajectories of live weight and carcass yield of Nile tilapia (Oreochromis niloticus). Data of live weight (8,758) and carcass yield (2,042) of tilapias with ages between 106 and 245 days were obtained from 72 families derived from 36 males and 72 females. The sex and tank variables were considered as classificatory and the coefficients of quadratic polynomials B-spline of two to five intervals of the same size were used as covariables. According to most fit criteria used, the models with quadratic B-spline polynomial with five intervals of the same size presented the best adjustments. The increase in number of intervals of B-spline polynomial improved the fit of the polynomials to the data. The inclusion of classificatory effects from sex, tank, the interaction of these effects and the quadratic polynomial B-spline nested in this interaction indicated that, over time, each sex, grown in different tank, presented different mean trajectory, necessitating the inclusion of nesting time in the interaction sex x tank in order to avoid the under or overestimation of breeding values of the selection candidates in breeding programs of this species.

A pure population of lung alveolar epithelial type II cells derived from human embryonic stem cells.

Alveolar epithelial type II (ATII) cells are small, cuboidal cells that constitute approximately 60% of the pulmonary alveolar epithelium. These cells are crucial for repair of the injured alveolus by differentiating into alveolar epithelial type I cells. ATII cells derived from human ES (hES) cells are a promising source of cells that could be used therapeutically to treat distal lung diseases. We have developed a reliable transfection and culture procedure, which facilitates, via genetic selection, the differentiation of hES cells into an essentially pure (>99%) population of ATII cells (hES-ATII). Purity, as well as biological features and morphological characteristics of normal ATII cells, was demonstrated for the hES-ATII cells, including lamellar body formation, expression of surfactant proteins A, B, and C, alpha-1-antitrypsin, and the cystic fibrosis transmembrane conductance receptor, as well as the synthesis and secretion of complement proteins C3 and C5. Collectively, these data document the successful generation of a pure population of ATII cells derived from hES cells, providing a practical source of ATII cells to explore in disease models their potential in the regeneration and repair of the injured alveolus and in the therapeutic treatment of genetic diseases affecting the lung.

Altered transmission of HOX and apoptotic SNPs identify a potential common pathway for clubfoot.

Clubfoot is a common birth defect that affects 135,000 newborns each year worldwide. It is characterized by equinus deformity of one or both feet and hypoplastic calf muscles. Despite numerous study approaches, the cause(s) remains poorly understood although a multifactorial etiology is generally accepted. We considered the HOXA and HOXD gene clusters and insulin-like growth factor binding protein 3 (IGFBP3) as candidate genes because of their important roles in limb and muscle morphogenesis. Twenty SNPs from the HOXA and HOXD gene clusters and 12 SNPs in IGFBP3 were genotyped in a sample composed of non-Hispanic white and Hispanic multiplex and simplex families (discovery samples) and a second sample of non-Hispanic white simplex trios (validation sample). Four SNPs (rs6668, rs2428431, rs3801776, and rs3779456) in the HOXA cluster demonstrated altered transmission in the discovery sample, but only rs3801776, located in the HOXA basal promoter region, showed altered transmission in both the discovery and validation samples (P = 0.004 and 0.028). Interestingly, HOXA9 is expressed in muscle during development. An SNP in IGFBP3, rs13223993, also showed altered transmission (P = 0.003) in the discovery sample. Gene-gene interactions were identified between variants in HOXA, HOXD, and IGFBP3 and with previously associated SNPs in mitochondrial-mediated apoptotic genes. The most significant interactions were found between CASP3 SNPS and variants in HOXA, HOXD, and IGFBP3. These results suggest a biologic model for clubfoot in which perturbation of HOX and apoptotic genes together affect muscle and limb development, which may cause the downstream failure of limb rotation into a plantar grade position.

A Rapid FACS-Based Strategy to Isolate Human Gene Knockin and Knockout Clones

Gene targeting protocols for mammalian cells remain inefficient and labor intensive. Here we describe FASTarget, a rapid, fluorescent cell sorting based strategy to isolate rare gene targeting events in human somatic cells. A fluorescent protein is used as a means for direct selection of targeted clones obviating the need for selection and outgrowth of drug resistant clones. Importantly, the use of a promoter-less, ATG-less construct greatly facilitates the recovery of correctly targeted cells. Using this method we report successful gene targeting in up to 94% of recovered human somatic cell clones. We create functional EYFP-tagged knockin clones in both transformed and non-transformed human somatic cell lines providing a valuable tool for mammalian cell biology. We further demonstrate the use of this technology to create gene knockouts. Using this generally applicable strategy we can recover gene targeted clones within approximately one month from DNA construct delivery to obtaining targeted monoclonal cell lines.

Temporal control of epigenetic centromere specification

All living organisms require accurate mechanisms to faithfully inherit their genetic material during cell division. The centromere is a unique locus on each chromosome that supports a multiprotein structure called the kinetochore. During mitosis, the kinetochore is responsible for connecting chromosomes to spindle microtubules, allowing faithful segregation of the duplicated genome. In most organisms, centromere position and function is not defined by the local DNA sequence context but rather by an epigenetic chromatin-based mechanism. Centromere protein A (CENP-A) is central to this process, as chromatin assembled from this histone H3 variant is essential for assembly of the centromere complex, as well as for its epigenetic maintenance. As a major determinant of centromere function, CENP-A assembly requires tight control, both in its specificity for the centromere and in timing of assembly. In the last few years, there have been several new insights into the molecular mechanism that allow this process to occur. We will review these here and discuss the general implications of the mechanism of cell cycle coupling of centromere inheritance.