Detection of Minchinia occulta in samples of pearl oysters Pinctada maxima infected by Haplosporidium hinei

Objective   To determine if juvenile pearl oysters ( Pinctada maxima ) infected with Haplosporidium hinei are also infected with another haplosporidian parasite, Minchinia occulta .
Design   Archived samples of pearl oysters infected with H. hinei were examined using polymerase chain reaction (PCR) assays and in situ hybridisation (ISH) to analyse and identify haplosporidians. A 144-bp and 220-bp region of Minchinia DNA were targeted by PCR and amplified DNA from formalin-fixed H. hinei -infected pearl oyster samples was sequenced. A 25-bp oligonucleotide probe targeting a variable section of the parasite's small subunit rRNA gene was used in ISH.
Results   The results of DNA-based diagnostic assays supported each other. The sequences obtained by PCR were found to be almost identical to M. occulta from rock oysters and the ISH assay demonstrated infection with M. occulta in affected pearl oysters. ISH indicated a prevalence of infection of 26.7% in one of the previous outbreaks.
Conclusion   Pearl oyster spat are susceptible to infection by a Minchinia parasite, most likely M. occulta , which was recently identified in rock oysters within the pearl-producing zones of Western Australia and is associated with mortalities of up to 80% in this species. The occurrence of haplosporidian co-infections in pearl oysters suggests the immunocompetence of juvenile oysters may be an important factor in preventing infection and therefore preventing mortalities such as those occurring in the recent outbreaks of pearl oyster oedema disease.     

Ecoepidemiology of the effects of pollution on reproduction and survival of early life stages in teleosts

Evidence from the field and laboratory has shown that reproduction and early life-stage survival of several species of teleost fishes have been adversely affected following the release of several classes of synthetic, organic chemicals into the environment. Field studies from many geographic areas over several decades have found associations between exposure to synthetic chemicals in the environment and effects on hatchability, embryological success and larval survival. In more recent research, exposure to sewage treatment and bleached kraft mill effluents has been correlated with changes in reproductive system development and alterations in the endocrine physiology of wild teleost fishes. Loss of fecundity and damage during various stages of development and reproduction have been associated with exposure to endocrine disruptors, including many currently used chemicals. The supporting laboratory studies have confirmed that various wild fish species are sensitive to certain synthetic chemicals at levels of exposure of parts per billion and parts per trillion, concentrations that are biochemically, physiologically, and environmentally relevant. This paper reviews the relevant field and laboratory research, and organizes the studies using the ecoepidemiological criteria of time-order, strength of association, specificity, consistency on replication, coherence and predictive performance. There is sufficient evidence to conclude that ambient concentrations of synthetic chemicals in some regions are at or above concentrations at which certain species could be affected. The viability of fishery resources must be linked not only to the quantity of habitat but also to the quality of habitat.     

Sexual Precocity of Nellore Bulls that are Offspring of Super Precocious,Precocious and Normal Cows in Extensive Farming Conditions

The objective of this work was to verify that mothers classified as super precocious (M1) and precocious (M2) produce more precocious bulls than females classified as normal (M3). This study included 21 186 animals with an average age of 21.29 ± 1.77 months that underwent a breeding soundness evaluation from 1999 to 2008. Of these animals, 2019, 6059 and 13 108 were offspring of M1, M2 and M3 females, respectively. In the breeding soundness examination, the animals were classified as sound for reproduction, sound under a natural mating regime, unsound for reproduction and discarded. To compare the averages obtained for each category of mother within the individual breeding soundness classes, a chi‐square test with a 5% error probability was used, considering the effects of year and month of birth and farm. For the three classes of mothers (M1, M2 and M3), 67.26, 67.22 and 64.16% of bull calves were considered sound for reproduction and 19.71, 19.46 and 21.90% were considered unsound for reproduction, respectively. There was no difference in the frequency of animals that were sound for reproduction under the natural breeding regime between the three classes of mothers (8.87, 9.31 and 9.19%, respectively). There was a difference between the numbers of precocious and normal females that were discarded, with frequencies of 4.01 and 4.75%, respectively (p < 0.05). There were differences in year and month of birth and farm between super precocious and precocious cows in relation to the breeding soundness classification of the animals. It was concluded that the bull offspring of super precocious and precocious cows presented a higher percentage of approval in the breeding soundness examination than the bull offspring of normal cows, demonstrating that the selection for precocity of females has contributed to an increase in the sexual precocity of the herd in relation to the sexual maturity of bulls.     

Comparative Development of Embryonic Age by Organogenesis in Domestic Dogs and Cats

The precise determination of the embryonic chronology is very important in reproductive biotechnologies, especially in estimating embryonic age. Thus, there is a need for greater knowledge and standardization for determining the chronology of embryonic development and functional morphology. We describe aspects of embryonic development in two domestic carnivores to add knowledge about organ peculiarities and for application in veterinary practice, in prenatal development and in the biotechnology fields. We found that the development of differential characteristics of embryonic organs occurs in the first trimester of pregnancy for both species. Thus, using the combination of the crown‐rump length, macroscopic analysis and optical microscopy, it is possible to predict gestational age more precisely in animals that lack a defined breed and establish an embryonic pattern.