Genetic diversity, nutritional and biological activity of Momordica cochinchinensis (Cucurbitaceae)

Momordica cochinchinensis (Lour.) Spreng belongs in the Cucurbitaceae family and is geographically restricted to South East Asia. The fruit possesses the highest amount of nutritionally important carotenoids (lycopene and ß-carotene) of all known fruits and vegetables including tomatoes and carrots by more than 200 and 54 times, respectively. Little information is available on the influence of genetic diversity and eco-geographical differences on the nutritional and medicinal potential of the fruit. This information is essential to assist future agricultural practices for the commercialisation of M. cochinchinensis as a new fruit in the medicine, food and nutrition industries. This thesis elucidated the variation in morphology, genetics, nutritional content (carotenoids) and biological activity (anticancer) of M. cochinchinensis collected from Vietnam, Thailand and Australia. M. cochinchinensis was morphologically and genetically diverse and the highest diversity was in Vietnam, indicating the presence of a diverse gene pool which contributed to superior nutritional and medicinal varieties. Molecular profiling of M. cochinchinensis samples based on morphology and molecular analyses (ISSR and RAPD) were in agreement and clustered the samples based on the country of origin. This study also indicated that the previously unknown origin of the Australian samples was from Southern Vietnam, an important finding for tracking the parentage of the plants grown in Australia and analysing the gene flow of M. cochinchinensis to Australia. The lycopene content was greater in samples from the Lam Dong and Lam Ha provinces of Central Vietnam as detected by HPLC and corresponded to larger and heavier seeds of M. cochinchinensis. Northern Vietnam samples possessed the highest levels of combined lycopene and ß-carotene. It is recommended that the varieties from Central and Northern Vietnam should be selected in future plant development for high carotenoids. Carotenoid accumulation was influenced by climatic factors, where lycopene accumulation was greatest at lower temperatures (<14°C) and higher elevations whilst b-carotene accumulation was greatest at temperatures between 27 to 33°C. These growth conditions should be replicated in future agriculture to enhance carotenoid accumulation in the fruit. Four different analytical methods were investigated to determine the accuracy and potential of analysis of carotenoid content in the M. cochinchinensis aril samples. Colorimetry, which was linked with redness of the aril correlated with higher lycopene concentrations as quantified by chromatography (HPLC, UPLC) and UV-visible spectrophotometry but this was not the case for b-carotene. This method could be used to rapid screen lycopene rich M. cochinchinensis in the field and will be useful for resource-poor farmers. Water extracts of the aril of M. cochinchinensis had a higher cytotoxicity on breast cancer and melanoma cells than the hexane based extracts. This suggested that the anticancer bioactive compounds extracted from the arils are not the carotenoids. The cytotoxicity of the water-based extract was selective towards breast cancer (MCF7) and melanoma (MM418C1 and D24) cells and not against normal human dermal fibroblast cells (NHDF). Furthermore, treatment of cells with the water extract caused both apoptotic and necrotic cell death. The cytotoxicity of the water extract was greater for samples obtained from Northern and Central Vietnam (>70% of cell death), especially those from the Ha Noi and Lam Dong provinces, respectively. High anticancer activity of the aril extract against melanoma cells were correlated with cool climates with low temperatures (<14°C) and a high precipitation during the driest month, indicating that these conditions facilitated the production of compounds responsible for anticancer activity. The findings of this study are novel and will assist current and future agricultural practices for the commercialisation of M. cochinchinensis as a new fruit in the medicine, food and nutrition industries

Climate Change and Soil Dynamics: A Crop Modelling Approach

The impact of global climate change is a challenge to the sustainability of many ecosystems, including soil systems. However, the performance of soil properties under future climate was rarely assessed. Therefore, this study was carried out to evaluate selected soil processes under climate change using an agri-environmental modeling approach to Sri Lanka. The Agricultural Production Systems Simulator (APSIM) model was used to simulate soil and plant-related processes using recent past (1990–2019) and future (2041–2070) climates. Future climate data were obtained for a regional climate model (RCM) under representative concentrations pathway 4.5 scenarios. Rainfalls are going to be decreased in all the tested locations under future climate scenarios while the maximum temperature showcased rises. According to simulated results, the average yield reduction under climate change was 7.4%. The simulated nitrogen content in the storage organs of paddy declined in the locations (by 6.4–25.5%) as a reason for climate change. In general, extractable soil water relative to the permanent wilting point (total available water), infiltration, and biomass carbon lost to the atmosphere decreased while soil temperature increased in the future climate. This modeling approach provides a primary-level prediction of soil dynamics under climate change, which needs to be tested using fieldwork

Chikungunya Virus Transmission at Low Temperature by Aedes albopictus Mosquitoes.

Aedes albopictus is an important vector of chikungunya virus (CHIKV). In Australia, Ae. albopictus is currently only known to be present on the islands of the Torres Strait but, should it invade the mainland, it is projected to spread to temperate regions. The ability of Australian Ae. albopictus to transmit CHIKV at the lower temperatures typical of temperate areas has not been assessed. Ae. albopictus mosquitoes were orally challenged with a CHIKV strain from either Asian or East/Central/South African (ECSA) genotypes (107 pfu/mL), and maintained at a constant temperature of either 18 °C or 28 °C. At 3- and 7-days post-infection (dpi), CHIKV RNA copies were quantified in mosquito bodies, and wings and legs using real time polymerase chain reaction (qRT-PCR), while the detection of virus in saliva (a proxy for transmission) was performed by amplification in cell culture followed by observation of cytopathic effect in Vero cells. Of the ≥95% of Ae. albopictus that survived to 7 dpi, all mosquitoes became infected and showed body dissemination of CHIKV at both temperatures and time points. Both the Asian and ECSA CHIKV genotypes were potentially transmissible by Australian Ae. albopictus at 28 °C within 3 days of oral challenge. In contrast, at 18 °C none of the mosquitoes showed evidence of ability to transmit either genotype of CHIKV at 3 dpi. Further, at 18 °C only Ae. albopictus infected with the ECSA genotype showed evidence of virus in saliva at 7 dpi. Overall, infection with the ECSA CHIKV genotype produced higher virus loads in mosquitoes compared to infection with the Asian CHIKV genotype. Our results suggest that lower ambient temperatures may impede transmission of some CHIKV strains by Ae. albopictus at early time points post infection

Chikungunya virus in Asia - Pacific: a systematic review.

Chikungunya virus (CHIKV) is a mosquito-borne pathogen that causes an acute febrile syndrome and severe, debilitating rheumatic disorders in humans that may persist for months. CHIKV's presence in Asia dates from at least 1954, but its epidemiological profile in the region remains poorly understood. We systematically reviewed CHIKV emergence, epidemiology, clinical features, atypical manifestations and distribution of virus genotypes, in 47 countries from South East Asia (SEA) and the Western Pacific Region (WPR) during the period 1954-2017. Following the Cochrane Collaboration guidelines, Pubmed and Scopus databases, surveillance reports available in the World Health Organisation (WHO) and government websites were systematically reviewed. Of the 3504 records identified, 461 were retained for data extraction. Although CHIKV has been circulating in Asia almost continuously since the 1950s, it has significantly expanded its geographic reach in the region from 2005 onwards. Most reports identified in the review originated from India. Although all ages and both sexes can be affected, younger children and the elderly are more prone to severe and occasionally fatal forms of the disease, with child fatalities recorded since 1963 from India. The most frequent clinical features identified were arthralgia, rash, fever and headache. Both the Asian and East-Central-South African (ECSA) genotypes circulate in SEA and WPR, with ECSA genotype now predominant. Our findings indicate a substantial but poorly documented burden of CHIKV infection in the Asia-Pacific region. An evidence-based consensus on typical clinical features of chikungunya could aid in enhanced diagnosis and improved surveillance of the disease

Temperature alters gene expression in mosquitoes during arbovirus infection

ABSTRACTArthropod-borne viruses (arboviruses) such as dengue, Zika and chikungunya constitute a significant proportion of the global disease burden. The principal vector of these pathogens is the mosquito Aedes (Ae.) aegypti, and its ability to transmit virus to a human host is influenced by environmental factors such as temperature. However, exactly how ambient temperature influences virus replication within mosquitoes remains poorly elucidated, particularly at the molecular level. Here, we use chikungunya virus (CHIKV) as a model to understand how the host mosquito transcriptome responds to arbovirus infection under different ambient temperatures. We exposed CHIKV-infected mosquitoes to 18 °C, 28 °C and 32 °C, and found higher temperature correlated with higher virus replication levels, particularly at early time points post-infection. Lower ambient temperatures resulted in reduced virus replication levels. Using RNAseq, we found that temperature significantly altered gene expression levels in mosquitoes, particularly components of the immune response. The highest number of significantly differentially expressed genes in response to CHIKV was observed at 28 °C, with a markedly more muted effect observed at either lower (18 °C) or higher (32 °C) temperatures. At the higher temperature, the expression of many classical immune genes, including Dicer-2 in the RNAi pathway, was not substantially altered in response to CHIKV. Upregulation of Toll, IMD and JAK-STAT pathways was only observed at 28 °C. Time post infection also led to substantially different gene expression profiles, and this effect varied depending upon the which temperature mosquitoes were exposed to. Taken together, our data indicate temperature significantly modulates mosquito gene expression in response to infection, potentially leading to impairment of immune defences at higher ambient temperatures.</jats:p

Temperature modulates immune gene expression in mosquitoes during arbovirus infection.

The principal vector of dengue, Zika and chikungunya viruses is the mosquito Aedes aegypti, with its ability to transmit pathogens influenced by ambient temperature. We use chikungunya virus (CHIKV) to understand how the mosquito transcriptome responds to arbovirus infection at different ambient temperatures. We exposed CHIKV-infected mosquitoes to 18, 28 and 32°C, and found that higher temperature correlated with higher virus levels, particularly at 3 days post infection, but lower temperature resulted in reduced virus levels. RNAseq analysis indicated significantly altered gene expression levels in CHIKV infection. The highest number of significantly differentially expressed genes was observed at 28°C, with a more muted effect at the other temperatures. At the higher temperature, the expression of many classical immune genes, including Dicer-2, was not substantially altered in response to CHIKV. The upregulation of Toll, IMD and JAK-STAT pathways was only observed at 28°C. Functional annotations suggested that genes in immune response and metabolic pathways related to energy supply and DNA replication were involved in temperature-dependent changes. Time post infection also led to substantially different gene expression profiles, and this varied with temperature. In conclusion, temperature significantly modulates mosquito gene expression in response to infection, potentially leading to impairment of immune defences at higher temperatures

A Gaussian model approach to determine the commencement, termination and length of the major growing season over the dry zone of Sri Lanka

Abstract The commencement, termination and length of the major (Maha) growing season over the dry zone of Sri Lanka were determined using daily rainfall records from 1981 to 2019 of five meteorological stations (Anuradhapura, Polonnaruwa, Hambantota, Puttalam and Batticaloa). Cumulative percentages of daily rainfall were plotted against the time and maximum positive and maximum negative curvatures were derived as the commencement and termination dates of the season. A Gaussian model was fitted on the cumulative distribution curve in order to remove limitations in deriving maximum positive and maximum negative curvatures. The difference between commencement and termination dates were taken as the length of the growing season. Results disclosed that there is a considerable inter-annual variation of commencement and termination dates and the length of the Maha season. Mean commencement and termination dates fall in the standard week 44.04±2.61 (end of October) and 5.10±4.20 (1st week of February). The average seasonal length is 13.7±4.24 weeks. Terminating date acts as the key determinant of the seasonal length. Any significant (p &gt; 0.05) trend could not be observed for commencement, termination and length of the season for the analyzed period in any of the locations. It can be concluded that cumulative distribution of rainy days can be successfully used to determine commencement and termination dates of the Maha season over the dry zone of Sri Lanka where a single peak rainy period is available. However, the method needs modifications, when it applies in wet zone of the country where bimodal rainfall pattern is prominent.</jats:p

Effect of HTST Thermal Treatments on End-Use Quality Characteristics of Goat Milk

Goat milk samples were pasteurized at high-temperature (72°C, 75°C, and 81°C) and in short-time (15 s and 25 s) combinations. Physical, chemical and microbial qualities of the pasteurized milk samples were evaluated 0, 2, 3, and 4 weeks of storage at 4°C. Despite the different thermal treatments, specific-gravity and viscosity were comparatively stable immediately after pasteurization (IAP). The viscosity of pasteurized milk at 81°C showed significant increase (P<0.05) from 1.58 ± 0.18 to 2.30 ± 0.15 mPa s during four weeks of storage. Relative lightness “L” value decreased by about 10% during the storage period of 81°C pasteurization samples. Acidity increased with heat treatment irrespective of holding time, but in 81°C pasteurized sample higher acidity was developed at end of the storage. Fat oxidation 2-3 times higher at 81°C than 72°C pasteurized samples. Total protein (TP%) and nonprotein nitrogen contents were stable IAP but TP reduced significantly (P<0.05) at two weeks storage. The whey protein denaturation increased with pasteurization treatments and storage time. Antioxidant activity of raw goat milk was 34.8 ± 5.01 μmol l−1 and was decreased by 20–43% IAP compared to raw milk samples, but gradually increased during storage. IAP, mesophilic counts were in the range of 980–110 cfu ml−1 (72°C/15–81°C/25 s) and increased from 2236 to 680 cfu ml−1 samples stored at 4 weeks. Results showed that best quality stability of pasteurized goat milk achieved by heat treatments between 72°C/25 s and 75°C/25 s heat treatments up to 3 weeks of storage under 4°C

Effect of HTST Thermal Treatments on End-Use Quality Characteristics of Goat Milk

Goat milk samples were pasteurized at high-temperature (72°C, 75°C, and 81°C) and in short-time (15 s and 25 s) combinations. Physical, chemical and microbial qualities of the pasteurized milk samples were evaluated 0, 2, 3, and 4 weeks of storage at 4°C. Despite the different thermal treatments, specific-gravity and viscosity were comparatively stable immediately after pasteurization (IAP). The viscosity of pasteurized milk at 81°C showed significant increase (P&lt;0.05) from 1.58 ± 0.18 to 2.30 ± 0.15 mPa s during four weeks of storage. Relative lightness “L” value decreased by about 10% during the storage period of 81°C pasteurization samples. Acidity increased with heat treatment irrespective of holding time, but in 81°C pasteurized sample higher acidity was developed at end of the storage. Fat oxidation 2-3 times higher at 81°C than 72°C pasteurized samples. Total protein (TP%) and nonprotein nitrogen contents were stable IAP but TP reduced significantly (P&lt;0.05) at two weeks storage. The whey protein denaturation increased with pasteurization treatments and storage time. Antioxidant activity of raw goat milk was 34.8 ± 5.01 μmol l−1 and was decreased by 20–43% IAP compared to raw milk samples, but gradually increased during storage. IAP, mesophilic counts were in the range of 980–110 cfu ml−1 (72°C/15–81°C/25 s) and increased from 2236 to 680 cfu ml−1 samples stored at 4 weeks. Results showed that best quality stability of pasteurized goat milk achieved by heat treatments between 72°C/25 s and 75°C/25 s heat treatments up to 3 weeks of storage under 4°C.</jats:p