• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • 1
  • 1
  • Tagged with
  • 4
  • 4
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Effect of environmental factors on the spawning, egg hatching and metamorphosis of nauplius of the shrimp Acetes intermedius (Omori, 1975)

Chen, Yung-Hui 31 July 2000 (has links)
The planktonic shrimp Acetes intermedius is an ecologically and commercially important species. Since it was described by Omori(1975) as a new species, there have been relative few studies focused on the reproduction of this species. The aim of this study is to examine the spawning, egg hatching, larval development of A. intermedius and the related environmental factors. The newly released eggs of Acetes intermedius were round, 200 um in diameter in average, transparent, demersal and were usually green in color. The cleavage pattern of developing egg is holoblastic. Larval stages could be divided into four stages: nauplius, protozea, zoea and postlarva. Nauplius, protozoea and zoea can be further divided into 4, 3 and 2 substages, respectively. At water temperature 30 ¢J and salinity 25 psu, hatching of nauplius was around 10-11 h after spawning while protozoea, zoea and postlarva occurred around 29h, 5-6 and 7 days after spawning, respectively. Newly released eggs were introduced directly into different temperature-salinity combinations. The results revealed that eggs failed to hatch at 15¢J at all salinities tested and at salinities 0 to 10 psu at all temperatures examined. Hatching success started to decrease at salinity 15 psu at 30¢J and at 20 psu at both 25¢J and 20¢J. When salinity was not lower than 25 psu, the hatching success reaches nearly 90 % in average and is generally similar among temperatures tested. Hatching started at about 10, 14 and 28h after spawning at temperatures 30, 25, 20¢J, respectively. At salinity 25 psu, hatching time was the shortest at both 25 and 30¢J, whereas it was similar among salinities at 20¢J. Eggs and nauplii I hatched at 30 ¢J, 30 psu were incubated in the different temperature-salinity combinations. It took eggs incubated at salinities ranging from 20 to 35 psu about 28, 45 h and 5 days to develop into protozoea I at 30, 25 and 20 ¢J, respectively. Nauplii usually started to metamorphose earlier at 25 and 30 psu than at 35 and 20 psu at 25 and 30¢J while no significant trend in metamorphosis time was found among different salinities at 20¢J. Nearly 90% of nauplii metamorphosed into protozoea I at 25 and 30¢J while the metamorphosis rate of nauplii was greatly reduced at 20¢J. The metamorphosis rate was usually higher around 20-25 psu and lower at 15 and 35 psu in all temperatures examined. While spawning, the gravid females swam near the water surface and were rapidly beating pleopods. The eggs were directly released into water. Spawning usually took place at night but the timing is generally peaked around midnight. The gravid females spawned in the early spring before midnight while they spawned after midnight in summer. The spawning timing is delayed at low temperature (24¢J) while it is not affected by high temperature (30¢J). The salinity did not show any effects on spawning but the hatching success of eggs released at 15 and 35 psu was significantly lower than those at 20-30 psu. The gravid females were tended to be endogenous timed to spawn in the night since spawning was not affected by absence of presence of light.
2

The Potential of Triclabendazole in Combination with Praziquantel for the Treatment of Schistosoma mansoni Infections

sbong@murdoch.edu.au, Sze How Bong January 2007 (has links)
Previous work has suggested that triclabendazole, a member of the benzimidazole group of compounds, possessed efficacy against Schistosoma mansoni. In view of recent indications in praziquantel treatment failures and loss of sensitivity, it is imperative that new anti-schistosomals are developed as contingent treatment options, while resistance alleles, if any, remain at low frequencies. While recent studies have indicated that triclabendazole monotherapy exert weak anti-schistosomal effects, the combinatorial application of triclabendazole with praziquantel has not been explored. To assess this hypothesis, triclabendazole and its metabolites were initially assessed against the many life-stages of Schistosoma mansoni in vitro. Combinatorial drug and isobologram analyses against adult Schistosoma mansoni was also performed, and subsequently applied against other parasitic models (Giardia duodenalis and Haemonchus contortus) to assess the specificity of such effects. Subsequently, the drug combinations were assessed against Schistosoma mansoni in vivo. To further assess the suitability of combinatorial drug applications, an economic model was developed to project the cost-efficacy of praziquantel-triclabendazole drug combinations in a global focus. It was concluded that triclabendazole and its metabolites possessed good efficacy against immature schistosomula, albeit weak efficacy against adult Schistosoma mansoni. Upon combination with praziquantel, however, a strong synergistic effect against adult worms were observed in vitro. Praziquantel and triclabendazole were also shown to possess unique and independent ovicidal modes of action that can be of clinical significance. More importantly, in vivo drug trials concluded that the combinations exerted additive effects against Schistosoma mansoni harbored in mice. Economic modeling and cost-effectiveness analyses further demonstrated the feasibility of this drug combination, and may represent a new line of treatment against mansonial schistosomiasis
3

Synthese von Trihydroxyeicosansäuren zur Bestimmung der absoluten Konfiguration des d"egg-hatching-factors" bei Seepocken

Müller, Markus. Unknown Date (has links) (PDF)
Techn. Universiẗat, Diss., 2003--Braunschweig.
4

Analysis of the Impact Hyperglycemia has on Neuronal Functions Using Genetic Approaches in Caenorhabditis elegans

Ruiz, Manuel Axel 05 1900 (has links)
A chronic hyperglycemic state often results in neuropathological complications such as peripheral diabetic neuropathy (PDN). PDN is a debilitating medical condition that impacts over half of the US population with diabetes. In this study, we used the model organism Caenorhabditis elegans to determine that glucose-supplemented diet leads to an increased rate of intrauterine egg hatching (IUEH) and the reduction of dopamine and serotonin is sufficient to suppress the glucose-induced IUEH. Moreover, in this research demonstrates that a glucose-supplemented diet impacts serotonin and dopamine-associated behaviors. Additionally, we demonstrate that a diet rich in glucose impacts the structure of the serotonergic neurons HSN and NSM. These findings highlight the utility of the model organism C. elegans in elucidating the impact of a glucose-supplemented diet on the nervous system. Finally, these studies show that a glucose-supplemented diet impacts transgenerational and intergenerational phenotypes as well as changes in the transcriptional profile of subsequent generations.

Page generated in 0.0688 seconds