The effect of consequent exposure of stress and dermal application of low doses of chlorpyrifos on the expression of glial fibrillary acidic protein in the hippocampus of adult mice

<p>Abstract</p> <p>Background</p> <p>Chlorpyrifos (CPF), a commonly used pesticide worldwide, has been reported to produce neurobehavioural changes. Dermal exposure to CPF is common in industries and agriculture. This study estimates changes in glial fibrillary acidic protein (GFAP) expression in hippocampal regions and correlates with histomorphometry of neurons and serum cholinesterase levels following dermal exposure to low doses of CPF with or without swim stress.</p> <p>Methods</p> <p>Male albino mice were separated into control, stress control and four treatment groups (n = 6). CPF was applied dermally over the tails under occlusive bandage (6 hours/day) at doses of 1/10th (CPF 0.1) and 1/5th dermal LD₅₀(CPF 0.2) for seven days. Consequent treatment of swim stress followed by CPF was also applied. Serum cholinesterase levels were estimated using spectroflurometric methods. Paraffin sections of the left hippocampal regions were stained with 0.2% thionin followed by the counting of neuronal density. Right hippocampal sections were treated with Dako Envision GFAP antibodies.</p> <p>Results</p> <p>CPF application in 1/10th LD₅₀did not produce significant changes in serum cholinesterase levels and neuronal density, but increased GFAP expression significantly (p < 0.001). Swim stress with CPF 0.1 group did not show increase in astrocytic density compared to CPF 0.1 alone but decreased neuronal density.</p> <p>Conclusions</p> <p>Findings suggest GFAP expression is upregulated with dermal exposure to low dose of CPF. Stress combined with sub-toxic dermal CPF exposure can produce neurotoxicity.</p

Malaysian herbs as feeding attractants and enhancers for the giant freshwater prawn (Macrobrachium rosenbergii) and the whiteleg shrimp (Litopenaeus vannamei)

Feeding attractiveness of 21 fresh herbs was examined for the giant freshwater prawn (Macrobrachium rosenbergii) and the whiteleg shrimp (Litopenaeus vannamei) at different growth stages in tanks. The feeding attractant and enhancement were assessed by behavioural observations of the test animals in response to pelleted feeds incorporated with the herbal extracts in different concentrations. For M. rosenbergii, peppermint (Mentha piperita) and dokudami (Houttuynia cordata) were the most attractive herbs at all stages, and garlic (Allium sativum) strongly attracting to the juveniles but only weekly to the adults, postlarvae and larvae. Peppermint significantly enhanced feeding of M. rosenbergii at all stages except for the larvae. Garlic was a significant feeding enhancer for M. rosenbergii juveniles and postlarvae. The inclusion of the herbal extract at high concentrations had a negative effect on the feeding. As far as L. vannamei is concerned, the red chilli (Capsicum annuum) was the best feeding attractant and ginger (Zingiber officinale) and peppermint were moderate attractants for adults and juveniles. While galangal (Alpinia galangal), ginger and yellow onion (Allium cepa sp.) enhanced feeding in L. vannamei adults, but red chilli, garlic and peppermint did not enhance feeding. Evidently, the strong feeding attractants were not necessarily effective feeding enhancers. The incorporation of several herb extracts at higher concentrations caused a negative effect on the feeding of the test animals. This could be due to the presence of feeding deterrents in the herb such as saponins which are known to lower food palatability in insect, decapod crustaceans and fishes. More long-term work is warranted to determine if inclusion of feeding enhancing herbs in artificial feed promotes growth performance of the shrimp

Sense organs development in larvae of the Sultan fish Leptobarbus hoevenii

At hatching, the sense organs of the Leptobarbus hoevenii larvae were morphologically immature. However, these sense organs had developed and became functional (including first occurrence of the intra-oral taste buds) to facilitate the larval first exogenous feeding at 3 days post-hatching (dph), before the yolk sac was completely absorbed at 5 dph. During the larval metamorphosis period (5–30 dph), the larval notochord flexion and fin development had completed. The retinal rods appeared at 5 dph, and its number increased with larval growth. The lagena was formed and the inner ears were fully calcified at 15 dph, indicating that the inner ears were completely developed. The olfactory organ development was completed when the anterior and posterior pits were formed at 30 dph. Canal neuromast was first found in the 30 dph L. hoevenii head portion, but none was observed at its trunk. Further examination of the elder stage (> 30 dph) of L. hoevenii is necessary to confirm the timing of trunk canal neuromast development. These findings have provided new biological information related to the L. hoevenii migratory life history in the field, as well as insight to improve the L. hoevenii larval rearing protocols

Feeding and nutrient requirements of Sultan fish, Leptobarbus hoevenii: A review

Sultan fish (Leptobarbus hoevenii) is a commercially important freshwater fish with high potential for aquaculture production in the Southeast Asian countries, including Malaysia. Many studies have been focused on its nutrition and trophic biology but the feeding practices in the farming have not yet been reviewed. This paper reviews on nutritional management of L. hoevenii broodstock, larvae and juveniles in culture systems. In general, there are feeding guidelines developed for the L. hoevenii farming but they are not fully supported with the scientific studies. Knowledge on the larval developmental biology is lacking to fully understand the feeding ecology of this fish. In addition, there is a paucity of data on requirements of various major nutrients in L. hoevenii at different life stages. Further studies on these topics are essentially required to improve the feeding practices in the farming of L. hoevenii

Effects of maternity leave expansion on female labour demand and birth rates : a theoretical analysis

This paper aims to investigate the effects of extended maternity leave on female labour demand and the overall birth rate. To address these issues, we develop two models based on the cost-benefit analysis and optimisation approach respectively. In essence, the models demonstrate several important insights. First, the effects of more maternity leave on female labour demand depend on the nature of a job, but are generally deleterious to female job applicants. Second, longer maternity leave does not necessarily incentivise women to have more children. To the extent that the models hold true, they imply that extended maternity leave, while an appealing policy option, can actually backfire. There is also a limit to how far birth rates can increase, if at all, in response to a longer period of paid maternity leave, especially in developed countries. This gives rise to the need for policies that influence such fundamentals as attitudes toward having children, rather than maternity leave alone. Given the crucial implications of both models, we recognise the importance of further empirical research in testing their predictive power.Bachelor of Art

Touch-sensitive bristles on the carapace of the mud crab Scylla paramamosain may be receptors for courtship signals

Bristle patches on the carapace behind the eyes were found for the first time in both males and females of the four species of mud crab Scylla spp. Electrocardiography revealed that the bristle patches of Scylla paramamosain were sensitive to touch (with a glass capillary) but not to chemical stimulation (with sugarcane juice). To elucidate the function of these touch signals, the courtship behaviour of S. paramamosain was video-recorded in a broodstock tank. A male approached a female, extended a walking leg over her carapace, touched her bristle patches with a dactyl, mounted her, and probed the bristle patches further with the third maxillipeds. Touch stimulus may be a signal for courtship in Scylla and one of the chain stimuli for the completion of mating behaviour.This study was partially funded by Universiti Malaysia Sabah grant SDK0028-2018

Touch‑sensitive bristles on the carapace of the mud crab Scylla paramamosain may be receptors for courtship signals

Bristle patches on the carapace behind the eyes were found for the frst time in both males and females of the four species of mud crab Scylla spp. Electrocardiography revealed that the bristle patches of Scylla paramamosain were sensitive to touch (with a glass capillary) but not to chemical stimulation (with sugarcane juice). To elucidate the function of these touch signals, the courtship behaviour of S. paramamosain was video-recorded in a broodstock tank. A male approached a female, extended a walking leg over her carapace, touched her bristle patches with a dactyl, mounted her, and probed the bristle patches further with the third maxillipeds. Touch stimulus may be a signal for courtship in Scylla and one of the chain stimuli for the completion of mating behaviour