Studies of the mechanism of action of asulam in plants. Part I: Antagonistic interaction of asulam and 4-aminobenzoic acid

Studies have been carried out on the herbicidal action of asulam [methyl (4-aminophenylsulphonyl)carbamate] and sulphanilamide, alone or in association either with 4-aminobenzoic acid (4ABA) or 4, 6-diamino-1-(3, 4-dichlorophenyl)-1, 2-dihydro-2, 2-dimethyl-1,3,5-triazine (DCDT). The soaking of wheat seeds (Triticum estivum L.) for 12 h at 30°C in asulam and DCDT in a 10:1 ratio doubled the inhibition of root growth produced by soaking in asulam alone; the addition of 4ABA partially reversed the activity of asulam. Foliar applications of a mixture of asulam + DCDT (1.1 + 0.55 kg ha^?1) markedly increased the activity of asulam in susceptible wheat, wild oat (Avena fatua L.), tolerant flax (Linum usitatissimum L.), and in Stellaria media L. The activity of asulam at 1.1 kg ha^?1 was reversed by 4ABA at 2.2 kg ha^?1 by about 50% in wheat and wild oat, 82% in flax and 100% in S. media. The results indicate that asulam and sulphanilamide act by similar mechanisms in apparently inhibiting the biosynthesis of folic acid.     

Socio-spatial organization reveals paternity and low kinship in the Honduran white bat (Ectophylla alba) in Costa Rica

Ectophylla alba is a tent-making bat that roosts in mixed-sex clusters comprising adults and offspring. Our goal was to determine the genetic identity of individuals belonging to different roosting groups. We tested the hypothesis of kin selection as a major force structuring group composition. We used 9 microsatellites designed for E. alba to determine the genetic identity and probability of parentage of individuals. We analyzed parentage and kinship using the software ML-Relate, GenAIEx, and Cervus. The obtained relationship probabilities (0.5) revealed a clear maternal relationship between female adults and offspring with allele compatibility, and at least 5 relationships between male adults and pups. We found a low degree of relatedness within roosting groups. Between roosting groups at different sites, the mean probability of a half-sibling relationship ranged from 0.214 to 0.244 and, for full-sibling relationship, from 0.383 to 0.553. Genetically, adult individuals were poorly related within clusters, and kinship as an evolutionary force could not explain group membership.     

Fasciola hepatica: Histology of the testis in egg-producing adults of several laboratory-maintained isolates of flukes grown to maturity in cattle and sheep and in flukes from naturally infected hosts

A total of 8 calves approximately 6 months old and 22 lambs of similar age were infected with metacercariae of Fasciola hepatica of various laboratory-maintained isolates including: Cullompton (sensitive to triclabendazole) and Sligo, Oberon and Leon (reported as resistant to triclabendazole). Ten to 16 weeks after infection, flukes were harvested from these experimental animals and the histology of the testis tissue was examined in a representative sample of flukes from each population. Adult wild-type flukes were also collected from 5 chronically infected cattle and 7 chronically infected sheep identified at post-mortem inspection. The testis tissue of these flukes was compared with that of the various laboratory-maintained isolates. Whilst the testes of the wild-type, Oberon and Leon flukes displayed all the usual cell types associated with spermatogenesis in Fasciola hepatica (spermatogonia, spermatocytes, spermatids and mature sperm), the Cullompton flukes from both cattle and sheep showed arrested spermatogenesis, with no stages later than primary spermatocytes represented in the testis profiles. The presence of numerous eosinophilic apoptotic bodies and nuclear fragments suggested that meiotic division was anomalous and incomplete. In contrast to the wild-type flukes, no mature spermatozoa were present in the testes or amongst the shelled eggs in the uterus. A high proportion of the eggs collected from these flukes hatched to release normal-appearing miracidia after an appropriate incubation period, as indeed was the case with all isolates examined and the wild-type flukes. It is concluded that the eggs of Cullompton flukes are capable of development without fertilization, i.e. are parthenogenetic. The implications of this for rapid evolution of resistant clones following an anthelmintic selection event are discussed. Amongst the Sligo flukes examined, two subtypes were recognised, namely, those flukes with all stages of spermatogenesis and mature spermatozoa present in the testes (type 1), and those flukes with all stages of spermatogenesis up to spermatids present, but no maturing spermatozoa in the testes (type 2). Each sheep infected with the Sligo isolate had both type 1 (approximately 60%) and type 2 (approximately 40%) flukes present in the population. Spermatozoa were found amongst the eggs in the uterus in 64% of flukes and this did not necessarily reflect the occurrence of spermatozoa in the testis profiles of particular flukes, suggesting that cross-fertilization had occurred. The apparent disruption of meiosis in the spermatocytes of the Cullompton flukes is consistent with reports that Cullompton flukes are triploid (3n=30), whereas the Sligo and wild-type flukes are diploid (2n=20). In the Sligo flukes the populations are apparently genetically heterogenous, with a proportion of the flukes unable to produce fully formed spermatozoa perhaps because of a failure in spermiogenesis involving elongation of the nucleus during morphogenesis.     

Traders' preference for goat characteristics in selected markets of Pangasinan, Philippines

Preference for goat characteristics was determined from 42 traders in six markets in Pangasinan, an important trading center for goats in Luzon, the Philippines, and analyzed using a hedonic price model to determine whether these characteristics are important price determinants of goats. This information is important to goat raisers to respond to the needs of the local market, and thus to achieve a better price and higher income in goat raising. Meatiness, size, breed, sex and age (in descending order) were the dominant goat characteristics preferred by traders. Meatiness had the largest positive influence on price, with a price premium of US$6.24 (US$1.00 = PhP 53), whereas the age of the animal had the smallest influence at US$3.72. However, size and meatiness are manifestations of good breeds. Therefore, continued efforts to improve breeds in order to produce good quality goats are imperative to cater to market needs. Different characteristics implied different price premiums. Traders offered a higher price premium for better goat characteristics; thus, the improvement of these characteristics could result in higher returns for goat raisers.     

Increased expression of GAPDH protein is not indicative of nitrosative stress or apoptosis in liver of starved rainbow trout (Oncorhynchus mykiss)

Short-term starvation has been linked to in vivo protein degradation in liver of rainbow trout (Oncorhynchus mykiss). However, it is unclear whether this proposed increase in protein degradation is followed by programmed cell death (apoptosis) in liver of starved trout. A preliminary study in our laboratory revealed an isoform of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) protein that increased 4.5-fold in liver of starved trout. GAPDH is a glycolytic enzyme involved in other cellular functions, including apoptosis. Increased intracellular nitric oxide (NO) promotes nuclear translocation of GAPDH that is associated with increased apoptosis in mammals. If GAPDH protein is associated with apoptosis in rainbow trout, it could potentially be used as a biomarker of cellular stress in liver of teleost fish species. The purpose of this study was to determine whether increased GAPDH protein expression in liver of starved rainbow trout is associated with NO-induced apoptosis. Targeted proteomic analysis using multiple reaction monitoring (MRM) was used to determine the level of GAPDH in nuclear and cytoplasmic fractions and inducible nitric oxide synthase (iNOS) in cell lysates. Dot blot and DNA fragmentation analyses were conducted to evaluate protein S-nitrosylation and apoptosis, respectively. Results showed that cytoplasmic GAPDH was 3.4-fold higher in liver of starved versus fed rainbow trout but could not be detected in nuclear fractions. Starvation significantly reduced hepato-somatic index but had no effect on iNOS protein expression, protein S-nitrosylation, or apoptosis. Our results indicate that starvation promoted significant reduction in liver mass that was not associated with increased apoptosis or NO-induced stress and that greater GAPDH concentration in liver of starved rainbow trout was located primarily in the cytoplasm.     

Effects of dietary β-carotene on the immune response of rainbow trout Oncorhynchus mykiss

SUMMARY: We attempt to assess the impact of different levels of dietary β-carotene on immune function in rainbow trout. Semi-purified diets containing 0, 40, 200, and 400 mg β-carotene/kg dry diet were fed for 12 weeks to fish with average weight of 45 g. In addition to the humoral and cellular immune parameters, growth and feed utilization were examined. There were no marked differences in growth and feed utilization showing that β-carotene was not particularly efficient in enhancing growth of rainbow trout. Of the immune parameters measured, total immunoglobulin was significantly highest for the 200 mg β-carotene fed group. Serum complement activity (alternate pathway) at 200 and 400 mg β-carotene supplementation was significantly higher than that of the unsupplemented group. An increasing trend in lysozyme activity was observed, however, the differences among the groups were not significant. Phagocytic activity was similar among diet groups except at the highest level of supplementation where it was the maximum. Oxygen radical production by peripheral blood leukocytes appeared to be lower at higher levels of carotenoid supplementation. Overall, dietary β-carotene clearly enhanced immune response parameters in rainbow trout such as serum complement activity and total plasma immunoglobulin but did not show a definite influence for the other factors examined in the present study.     

Reinventing residual reserves in the sea: are we favouring ease of establishment over need for protection?

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