Characteristics of Progesterone Synthesis In Isolated Luteal Cells

Single cells were prepared from the luteinized rat ovary, and the characteristics of progesterone synthesis by these cells were examined. The isolated luteal cells were viable and functional, and respond to luteinizing hormone (LH) stimulation by synthesizing progesterone in vitro. In the absence of exogenous glucose, the rate of progesterone synthesis was 0.23 ng/ml/min. LH increased this rate 2-fold, and the duration of the initial linear phase of this reaction was sustained for up to 60 min, compared to the controls which were linear for only 15 min. This effect was dose-related: maximal stimulation was achieved with 1 J1g LH/ml, while a minimal but significant stimulation was elicited with 61 pg/ml. This steroidogenic activity was also increased by the addition of exogenous glucose and bovine serum albumin. These data serve to establish the optimum conditions for the use of single cells in studies pertaining to mechanism of LH action

Development of hybrid aluminum-air battery fuel-cell system

Industrial 4.0 accelerates the need to introduce clean energy to accommodate the increase in electricity demand globally without causing environmental issues. Metal-air battery is a new type of energy storage system in which the metal anode is consumed to generate electricity through the electrochemical reaction. Among various types of the metal anode, aluminum is a promising energy carrier. Aluminum-air battery shows advantages such as high capacity, abundance, low cost, and being environmentally friendly. Traditional aqueous aluminum-air battery experiences restriction from application due to its self-corrosion issues. In this study, instead of reducing or limiting the self-corrosion issues, a different approach is proposed so to make use of the self-corrosion issues of the aluminum-air battery. By incorporating an additional hydrogen-air subcell to the aluminum-air battery, this hybrid system turned the self-corrosion issue into a beneficial reaction by utilizing the hydrogen gas produced from the aluminum anode as the fuel to power the hydrogen-air fuel cell and improving the overall power performance. The electrical performance of each system is studied experimentally using potassium hydroxide electrolytes. The hybrid system shows a great improvement as compared to a single system. The maximum power is improved by more than 40%. This study shows that the hybrid design is feasible in enhancing the aluminum-air battery performance and yet, maintaining low cost and low weight in nature

Analysis of the Polypropylene-Based Aluminium-Air Battery

Global energy demand is rising due to the rapid development and adoption of new technologies in every sector. Hence, there is a need to introduce a clean energy source that does not cause damage to the environment. Aluminium-air battery with its high theoretical specific volumetric capacity is an exciting alternative for post-lithium energy storage and has been at the forefront of energy research for years. However, the conventional aqueous electrolyte-based aluminium-air battery with bulky liquid storage, parasitic corrosion of aluminium in contact with the electrolyte, and formation of a passive oxide or hydroxide layer has precluded its widespread application. In order to achieve successful simplification and cost-effectiveness, a novel idea of a polypropylene-based aluminium-air battery is proposed. In this work, a polypropylene-based aluminium-air battery was constructed using aluminium foil as an anode, carbon fiber cloth as an air-cathode, and Polypropylene and Kimwipes as the separator. The effects of the electrolyte concentration on the aluminium-air battery were investigated and analyzed using various discharge currents. The study showed that the performance of the polypropylene separator is better than that of the Kimwipes separator. The battery capacity is negatively correlated with the concentrations of the electrolyte. At a discharge current of 30 mA, the aluminium-air battery has a specific capacity of 375 mAh g−1 when 1 M of potassium hydroxide was used as electrolyte

Entomologic and molecular investigation into Plasmodium vivax transmission in Singapore, 2009

<p>Abstract</p> <p>Background</p> <p>Singapore has been certified malaria free since November 1982 by the World Health Organization and despite occasional local transmission, the country has maintained the standing. In 2009, three clusters of malaria cases were reported in Singapore.</p> <p>Methods</p> <p>Epidemiological, entomological and molecular studies were carried out to investigate the three clusters, namely Mandai-Sungei Kadut, Jurong Island and Sembawang.</p> <p>Results</p> <p>A total of 29 malaria patients, with no recent travel history, were reported in the three clusters. Molecular analysis based on the <it>msp3α </it>and <it>msp1 </it>genes showed two independent local transmissions: one in Mandai-Sungei Kadut and another in Sembawang. Almost all cases within each cluster were epidemiologically linked. In Jurong Island cluster, epidemiological link remains uncertain, as almost all cases had a unique genetic profile. Only two cases shared a common profile and were found to be linked to the Mandai-Sungei Kadut cluster. Entomological investigation found <it>Anopheles sinensis </it>to be the predominant Anopheline in the two areas where local transmission of <it>P. vivax </it>was confirmed. <it>Anopheles sinensis </it>was found to be attracted to human bait and bites as early as 19:45 hrs. However, all <it>Anopheles </it>mosquitoes caught were negative for sporozoites and oocysts by dissection.</p> <p>Conclusion</p> <p>Investigation of <it>P. vivax </it>cases from the three cluster areas confirmed the occurrence of local transmission in two areas. Although <it>An. sinensis </it>was the predominant Anopheline found in areas with confirmed transmission, the vector/s responsible for the outbreaks still remains cryptic.</p

Standardization of the FAO/IAEA Flight Test for Quality Control of Sterile Mosquitoes

[EN] Successful implementation of the sterile insect technique (SIT) against Aedes aegypti and Aedes albopictus relies on maintaining a consistent release of high-quality sterile males. Affordable, rapid, practical quality control tools based on the male's flight ability (ability to escape from a flight device) may contribute to meeting this requirement. Therefore, this study aims to standardize the use of the original FAO/IAEA rapid quality control flight test device (FTD) (version 1.0), while improving handling conditions and reducing the device's overall cost by assessing factors that could impact the subsequent flight ability of Aedes mosquitoes. The new FTD (version 1.1) is easier to use. The most important factors affecting escape rates were found to be tube color (or "shade"), the combined use of a lure and fan, mosquito species, and mosquito age and density (25; 50; 75; 100 males). Other factors measured but found to be less important were the duration of the test (30, 60, 90, 120 min), fan speed (normal 3000 rpm vs. high 6000 rpm), and mosquito strain origin. In addition, a cheaper version of the FTD (version 2.0) that holds eight individual tubes instead of 40 was designed and successfully validated against the new FTD (version 1.1). It was sensitive enough to distinguish between the effects of cold stress and high irradiation dose. Therefore, the eight-tube FTD may be used to assess Aedes' flight ability. This study demonstrated that the new designs (versions 1.1 and 2.0) of the FTD could be used for standard routine quality assessments of Aedes mosquitoes required for an SIT and other male release-based programs.The authors are grateful to Empresa de Transformación Agraria S.A., S.M.E, M.P. (TRAGSA), Spain, and to Wolbaki, China, for donating their strain for testing. They are grateful to the two reviewers for their useful comments/suggestions that improved our manuscript. This research was funded by the United States of America under the grant to the IAEA entitled ¿Surge expansion for the sterile insect technique to control mosquito populations that transmit the Zika virus.¿ The funders and the agency had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.Maïga, H.; Lu, D.; Mamai, W.; Somda, NSB.; Wallner, T.; Bakhoum, MT.; Masso, OB.... (2022). Standardization of the FAO/IAEA Flight Test for Quality Control of Sterile Mosquitoes. Frontiers in Bioengineering and Biotechnology. 10:1-14. https://doi.org/10.3389/fbioe.2022.8766751141

Entomologic and Virologic Investigation of Chikungunya, Singapore

Data from longitudinal analyses can be useful in the design and implementation of control strategies

The role of cyclic amp in oocyte maturation of goldfish, Carassius auratus

The role of cyclic AMP in oocyte maturation was investigated using denuded goldfish oocytes cultured in vitro. The oocytes were stimulated with a maturation-inducing steroid (MIS), 17α, 20ß dihydroxy-4-pregnen-3-one (17, 20 P) with or without forskolin or forskolin only. Changes in cAMP concentrations and percent maturation of the oocytes were determined. Results showed that elevated levels of cAMP maintain the oocytes in meiotic arrest while a decrease would trigger the resumption of meiotic maturation

Identification of vectors of plasmodium knowlesi and other malaria parasites, and studies on their bionomics in Kapit, Sarawak, Malaysia

The aims of this project were to identify the vectors of P. knowlesi and other malaria parasites in Kapit and to study their bionomics. A one year entomological study was undertaken with three areas chosen as adult mosquito collection sites; a longhouse, where indoor and outdoor collections were undertaken, a farm and the forest, where an elevated platform for money bait trap was also built. The methods of collection were the bare-leg catch and the monkey baited-net trap

Vector competence of Aedes aegypti and Ae. albopictus from Singapore for dengue and other arboviruses

Globally, vector-borne diseases are the leading cause of morbidity and mortality, with dengue considered to be the most important mosquito-borne diseases affecting man. Singapore is hyperendemic to dengue with all serotypes co-circulating in different proportions. Despite having a comprehensive vector surveillance and control programme, the country is not spared from the resurgence of dengue. During the past 10 years, the country has experienced three major dengue epidemics, with the latest epidemic in 2013-14 considered to be the worst. Interestingly, these outbreaks occurred while the Aedes premise index was consistently kept at a low level of 1% or less. It was hypothesized that the aggressive vector control measures in Singapore has led to a very low mosquito population that could have selected for the circulation of a virus lineage with better fitness or population of vectors that are highly competent to transmit DENV. To elucidate this, vector competence studies were carried out to determine the susceptibility of local Aedes aegypti and Ae. albopictus to different dengue serotype 2 viral lineages. Results from these experiments seemed to be in agreement to both hypotheses. Although, both mosquitoes were highly susceptible to the virus, Ae. aegypti was found to have higher competence to transmit dengue 2. This further reinforces the role of Ae. aegypti as the key driver of dengue epidemics in Singapore. At present, there is neither a licensed vaccine nor a specific treatment for dengue, thus, control and prevention of the disease is still reliant in controlling vector population. The increase in human population, continued urbanization, coupled with human migration from dengue endemic countries and the worsening global dengue situation will make the future control of dengue in Singapore more challenging. In this study, Ae. aegypti and to a lesser extent, Ae. albopictus were also found to be highly susceptible to Zika and Ross River viruses. Introduction and establishment of exotic arboviruses in Singapore is highly plausible, especially with a population that is immunologically naïve to these pathogens. The first chikungunya outbreak in 2008 attests to these possibilities. Thus, there is an urgent need to enhance current vector surveillance and control programmes with alternative entomological approaches. The use of Wolbachia for the control and prevention of dengue and other vector-borne diseases can be a promising alternative control tool that can be implemented in Singapore. Although, the use of Wolbachia induced cytoplasmic incompatibility for suppression of Ae. aegypti population seemed to be the logical approach as it aligned with current vector control method being implemented. Tapping on the pathogen blocking ability induced by Wolbachia in Ae. aegypti should also be explored. Results from the current study showed that Wolbachia is able to reduce the ability of local Ae. aegypti in transmitting dengue to a level where it may have a significant impact on dengue transmission, as deduced from a recent Wolbachia transmission model study. In addition, this blocking ability is extended to chikungunya and zika viruses. This study also shows, for the first time, the ability of wMel to block Zika viru