The Effects of Stressful Broodstock Handling on Hormonal Profiles and Reproductive Performance of Rhamdia quelen (Quoy & Gaimard) Females

Abstract.— A stressful environment induces cortisol that might affect fish breeding and reproduction. In the present work, which aimed to mimic aquacultural conditions of the jundia (Rhamdia quelen) hatcheries in southern South America, females were submitted to normal or stressful handling and the effects of cortisol on serum levels of 17β‐estradiol (E2) and testosterone (T) were determined. In addition, the effect of stress on reproductive parameters such as eggs and swim‐up fry production was also measured. Eight females from a group submitted to stressful handling (SH) conditions and eight females from a group with normal handling (NH) conditions were captured for blood sampling at D 0 and at D 1, 10, 20, 30, and 40 of the experiment. A typical cortisol response was observed in the SH females group in that they presented higher cortisol level in contrast to the NH female group, in all days sampled, except at D 0. In the 10th and 20th d, the E2 levels were lower in SH females, but cortisol levels were higher, suggesting an effect of cortisol on E2 production and/or release. Stressful handling appeared to affect both the number and the quality of the gametes because a lower number of oocytes was stripped from SH females, and from SH fertilized eggs, a lower number of viable swim‐up fry was obtained to be transferred to earthen larviculture ponds. Taken together, the results indicated that stressful handling of broodstock impairs R. quelen reproduction.     

Temporal stability of multivariate genetic divergence in cacao ( Theobroma cacao L.) in Southern Bahia conditions

Stability of the genetic divergence among five non-commercial cacao cultivars at advanced ages was investigated over a five-year period (1986–1990). Cluster analysis was performed on five yield components measured on harvests from each crop year and on the data pooled over five years. The temporal stability was assessed by using clustering procedure, which involved the calculation Mahalanobis distance (D²) and of Tocher's algorithm applied to the distance matrix. The comparison of D² and of clusters based upon pooled analysis, and taken as the standard, with D² values and clusters obtained from each year showed a stable clustering pattern in the most favourable year. For the rest of the years, inconsistency in number and composition of clusters formed was observed. An optimum environment was shown to be important for better expressing divergence by D². Consequently, the evaluation of the genetic divergence among the studied cultivars may be conducted based on a single favourable year. This will result in considerable savings in man power, financial resources, and time which would be wasted should the evaluation be extended for several years.     

Identification of citrus hybrids through the combination of leaf apex morphology and SSR markers

Citrus breeding programs normally face several biological obstacles such as apomixis and polyembryony that result in a cumbersome identification of hybrid seedlings. The main purpose of this work is to describe the combined use of visual selection based on the leaf apex morphology and SSR analysis to differentiate hybrid from nucellar seedlings derived from the cross between the ‘Murcott’ tangor [Citrus reticulata Blanco × Citrus sinensis (L.) Osb.] and ‘Pêra’ sweet orange [Citrus sinensis(L.) Osb.]. A new morphological variable named leaf apex morphometric index is also described as the quantitative basis of the visual selection. The efficiency of visual selection of hybrids was tested under two growth conditions, seedlings germinated in seedbeds and in plastic tubes. Putative hybrid seedlings were also confirmed through the analysis of simple sequence repeats (SSR). The visual selection of hybrid seedlings resulted in an increase of 87.2% (p < 0.01) and 202.2% (p <0.001) in the number of correctly identified hybrids when compared to the method of random picking of seedlings in seedbeds and plastic tubes,respectively. The results indicate that the combination of visual selection and SSR analysis for the identification of hybrids derived from the cross of polyembryonic citrus cultivars will improve the accuracy of the selection,save time, and reduce the costs involved in the use of molecular markers alone in citrus breeding programs. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic control of low temperature tolerance in germination of the common bean (Phaseolus vulgaris L.)

Summary Cultivars tolerant to low temperature during the germination and emergence stages and carriers of the grain quality standards demanded by consumers are needed to increase the success of irrigated common bean in Southern Minas Gerais State. To study the genetic mechanisms controlling these traits and assess the possibility of generating the desirable materials, a diallel cross involving ten cultivars including introductions and pure lines from the breeding program of ESAL was carried out. Speed of germination of the F₂ generation from the crosses was assessed under laboratory conditions at 12°C. The diallel analysis was carried out using Griffing's method IV (1956) and predictions of the cross potential were made by the methodology developed by Jinks & Pooni (1986). The results indicated that the parents differed in germination speed at low temperatures with Small White, A-488 and Rio Vermelho being the most tolerant and Carioca, ESAL 591 the most sensitive. No effect of the reciprocal crosses was observed either for germination percentage or germination speed. The parents A-488, Small White and Rio Vermelho showed the greatest general combining ability. Additive genetic effects predominated for both traits. Our results suggest that cold tolerance can be bred successfully into commercially acceptable cultivars.     

Exploring the denaturation of whey proteins upon application of moderate electric fields: a kinetic and thermodynamic study

Thermal processing often results in disruption of the native conformation of whey proteins, thus affecting functional properties. The aim of this work was to evaluate the effects of moderate electric fields on denaturation kinetics and thermodynamic properties of whey protein dispersions at temperatures ranging from 75 to 90 °C. Application of electric fields led to a lower denaturation of whey proteins, kinetically traduced by lower values of reaction order (n) and rate constant (k) (p < 0.05), when compared to those from conventional heating under equivalent heating rates and holding times. Furthermore, the application of electric fields combined with short come-up times has reduced considerably the denaturation of proteins during early stages of heating (>30% of native soluble protein than conventional heating) and has determined also considerable changes in calculated thermodynamic properties (such as E(a), ΔH(?), ΔS(?)). In general, denaturation reactions during moderate electric fields processing were less dependent on temperature increase.     

Free cyclitol, soluble carbohydrate and protein contents in Vigna unguiculata and Phaseolus vulgaris bean sprouts

Seeds sprouts have been used as a good source of basic nutrients and nutraceutical compounds. The high nutritional value of seeds derives from the deposition of compounds during development. However some of these molecules are used in metabolic processes like germination, which leads to a considerable variation in their concentrations once these events are completed. In this work, we investigate the levels of inositols (myo-inositol, D-pinitol and ononitol), soluble carbohydrates and proteins in cotyledons of Phaseolus vulgaris and Vigna unguiculata sprouts. Sprouting increased myo-inositol and glucose content and reduction of raffinose and ononitol was observed. The protein levels increased in P. vulgaris and decreased in V. unguiculata sprouting. The level of sucrose was maintained in both sprouts. D-Pinitol was detected only in quiescent seeds. Our results suggested that bean sprout is an important source of proteins, sucrose, glucose and myo-inositol. Additionally, bean sprouts have low levels of raffinose, an antinutritional compound.     

Diagnosis of Eimeria species using traditional and molecular methods in field studies

The objective of this study was to identify and characterize species of Eimeria in broiler chickens using traditional morphological and pathological plus molecular (DNA amplification) diagnostic methodologies. Using a combination of those techniques it was possible to identify the presence of multiple circulating species in the flock as well as higher frequencies for some of them, especially Eimeria praecox and Eimeria maxima, which were identified in 100% of the flocks. The frequencies of the other species were Eimeria mitis and Eimeria necatrix (93.3%), Eimeria tenella (76,7%), Eimeria acervulina (56.7%) and Eimeria brunetti (16.7%). However using the lesion score, the most common species were E. maxima (46.7%), E. acervulina (30%), E. tenella (23.3%), and E. necatrix (10%). E. brunetti and E. praecox were not identified by using lesion score. DNA amplification had detection sensitivity for Eimeria species in the field samples of at least 20 oocysts. The implementation of DNA amplification as a routine diagnostic technique in aviaries can assist Eimeria population.     

Developmental plasticity in sexual roles of butterfly species drives mutual sexual ornamentation

Current explanations for why sexual ornaments are found in both sexes include genetic correlation, same sex competition, and mutual mate choice. In this study, we report developmental plasticity in mating behavior as induced by temperature during development in the butterfly Bicyclus anynana. Males and females reciprocally change their sexual roles depending on their larval rearing temperatures. This switch is correlated with a change in mating benefits to females and costs to males. The discrete seasonal environments, wet season and dry season, are known to produce the two developmental forms and as a consequence impose alternating, symmetrical patterns of sexual selection, one season on male ornaments, the following season on female ornaments. Thus, reciprocal selection through time may result in mutual sexual ornamentation.