Tropical life sciences research最新文献

"Terung asam" Sarawak (Solanum lasiocarpum Dunal) is an underutilised fruit vegetable. Information on the fruit growth is very lacking. Thus, this study was conducted to characterise fruit growth pattern based on physical characters and cellular structures. Data were recorded weekly from fruit set until senescence. All the morphological growth of "terung asam" fruit exhibits a single sigmoid growth pattern that fitted well to logistic model. There are three distinct phases of growth, i.e., S1, S2 and S3. At S1, the size of fruit cells was small without intercellular spaces. As fruit grew to S2, cell size increased with distinct vascular tissues. By S3, fruit has achieved its maximum size with green peel turn to yellow and finally golden yellow at late S3. Cuticle and two types of trichomes formed the outer layer of fruit. The thickness of fruit exocarp increased while density of trichomes decreased as fruit developed.

The Asian tapir is a primitive mammal whose habitat is heavily fragmented due to human activities. Studies on the Asian tapirs in Sumatra are very few, thereby basic information for developing tapir conservation programmes is limited. This study aimed to develop the species distribution model to map the potential distribution of tapirs in Batang Gadis National Park (BGNP), investigate the characteristic of tapir habitat, and identify tapir feed plants around BGNP. The model was developed using the Maximum Entropy (Maxent) approach, based on the existing information on tapir occurrence in BGNP and environmental variables. Vegetation characteristics in different land cover (primary forests, secondary forests, and open fields) were investigated using the strip transect method. This study found that zonal classification, temperature and precipitation have the greatest percentage contribution to the model. The model estimated that around 24.45% of BGNP areas are suitable for tapir habitat, and tapirs distribute near community gardens. Our results also showed that plant diversity at study sites was categorised as moderate-high. About 23 plant species dominated by the Moraceae family were identified as feed plants for tapirs. In developing tapir conservation programmes, BGNP management needs to consider tapir distribution that is closed to community gardens. We propose BGNP to enrich feed plants in open fields of the wilderness and traditional zones; reduce the canopy cover in the wilderness and utilisation zones to stimulate the growth of feed plants; facilitate local people to live harmoniously with tapirs; involve local communities in tapir conservation programmes; encourage local communities to plant non-palatable crops for tapirs; and provide a compensation scheme.

Associated gas flaring has several consequences on the environment. This study was aimed at assessing the impact of gas flaring on soil enzymes and plant antioxidant activities from gas flare-bearing communities in Nigeria. Soil and plant samples were obtained from farmlands in Ukwa West and Izombe gas flaring sites, as well as unpolluted site from Olokoro (used as control). The level of activities of soil urease, dehydrogenase, phosphatases, plant antioxidant enzymes and lactate dehydrogenase (LDH) of selected plants (Gnetum africanum [GA], Piper guineense [PG], Gongronema latifolium [GL], Pterocarpus mildbraedii [PM]) were evaluated using standard methods. The results showed that the activities of urease were significantly higher (P < 0.05) in soil from Ukwa site than Izombe and the control soil. Dehydrogenase (DHA) and phosphatases recorded higher activities (P < 0.05) for Izombe soil than in Ukwa compared with the control. For plants, superoxide dismutase (SOD), glutathione S-transferase (GST) and glutathione peroxidase (GPx) recorded a significant (P < 0.05) higher activities in all the plants assayed from Ukwa site than Izombe and the control site. The activities of GPx from GA and PG plants at Izombe site were not significant (P > 0.05) when compared with the control, except for PM and GL which recorded a significant decrease (P < 0.05) in GPX and SOD activities, respectively. The activities of catalase enzyme also decreased significantly (P < 0.05) in all plants grown at Ukwa, while an increase was seen for GA and PM grown at Izombe compared with control. The overall variability in enzymes activities is an indication that soil ecosystem and plants are altered significantly by the stress load from the gas flaring pollutants which could serve as bio-indicators for assessing ecological risks and bioremediation.

Bagworm Metisa plana is one of the major pests in Malaysia's oil palm plantation, with infestation resulting in huge economical loss. Currently, the microbial profile of the bagworm has yet to be study. Understanding the biology of the pest such as the bacterial community is crucial as bacteria associated with insects often provide benefits to the insect, giving the insect host a better chance of survival. Here, 16S amplicon sequencing was used to identify the bacteria community of M. plana. Additionally, two comparisons were made, the bacterial communities between two larval stages (early instar stage and late instar stage) from outbreak area; the bacterial communities of late instar stage larvae from non-outbreak between outbreak areas. From this study, it was found that the bacterial community of M. plana consisted of Proteobacteria, Actinobacteria, Bacterioidetes, Firmicutes and other minor phyla, with Proteobacteria being the most dominant phylum. Furthermore, bacterial genera of M. plana consisted of Pantoea, Curtobacterium, Pseudomonas, Massilia and other minor genera, with Pantoea being the most dominant. It was also found that the alpha and beta diversity in both comparisons were not significantly different. We present our data as a first insight towards the bacterial community of M. plana, paving a way towards understanding the biology of the bagworm M. plana.

The objective of this study was to investigate the mixed culture of Bacillus subtilis, B. licheniformis and B. megaterium to control acute hepatopancreatic necrosis disease (AHPND) or EMS (Early Mortality Syndrome) in white shrimp Litopenaeus vannamei as a model. The infected shrimps with Vibrio parahaemolyticus AHPND strain were divided into tanks and different feeding of either B. subtilis, B. licheniformis, B. megaterium or all Bacillus strains. The infected shrimps that were fed with a mixed culture of Bacillus showed significantly highest survival rate and revealed lower percent detection of V. parahaemolyticus AHPND strain by Polymerase Chain Reaction (PCR) (57.14%) with a small amount of viability count in their hepatopancreas. In contrast, the infected shrimps that were fed with each of B. subtilis, B. licheniformis or B. megaterium, revealed the spread of V. parahaemolyticus AHPND strain in all tissue by PCR detection (86.67%-100%) with a large amount of viability count (3.53 - 4.24 × 10³ CFU/g). This study indicated that the mixed culture of Bacillus subtilis, B. licheniformis and B. megaterium could control the dissemination of V. parahaemolyticus in shrimps, especially in hepatopancreatic that is the target tissue of AHPND in white shrimp (L. vannamei). The result of this study revealed the efficiency and mechanism of the mixed culture of B. subtilis, B. licheniformis and B. megaterium to control the virulence of AHPND and support the application of this mixed culture in aquaculture of shrimp farms to avoid chemical and antibiotic treatment by using it as a biological control.

Indole-3-acetic acid (IAA) is one of the most physiologically active auxins produced by rhizobacteria and is potentially applied for agriculture. Two endophytic bacteria, VR2 and MG9, isolated from the root of Chrysopogon zizanioides (L.) collected at Cha-Am, and the leaf of Bruguiera cylindrica (L.) Blume collected from a mangrove forest at Ban Laem, Phetchaburi Province, Thailand, were taxonomic characterised based on their phenotypic characteristics and 16S rRNA gene analysis. Strain VR2 was closely related to Enterobacter hormaechei CIP 103441^T (99.6% similarity), while strain MG9 was closely related to Bacillus aryabhattai B8W22^T (99.9% similarity). Consequently, they were identified as Enterobacter hormaechei and Bacillus aryabhattai, respectively. The IAA production of VR2 and MG9 strains are determined and applied to rice seeds for their root and shoot germination. Strains VR2 and MG9 greatly produced a yield of IAA, 246.00 and 195.55 μg/mL in 1,000 μg/mL of L-tryptophan at pH 6 for 48 h. They showed no significant differences in IAA to root and shoot development. However, the bacterial IAA exhibited potential nearby synthetic IAA, which had a significant effect compared to the control. IAA produced from these two strains might preferably trim down the use of synthetic IAA and could contribute to sustainable agriculture.

Sabah contributes 4.2 million hectares to the total Heart of Borneo (HoB) areas. Some of the forest reserves in the HoB are newly gazetted as Totally Protected Forest. Hence, their mammal diversity has to be comprehensively documented. This study aims to record the presence of terrestrial mammal species, and assess the prevalence of poaching in selected forest reserves within the Sabah HoB area. A total of 15 forest reserves were surveyed within a 5-year timeframe which recorded 60 terrestrial mammal species, including 21 Bornean endemics. The variation in total enumerated mammal species in the study sites may be derived from unequal sampling efforts, geographical factors and anthropogenic influences. The intensity of poaching within the study sites is high. Though this study is a rapid assessment, it created baseline information for mammal diversity in some of the least studied forest reserves in Sabah, important for conservation of its terrestrial mammals.

Limited data are available regarding the effects of Brachiaria decumbens on sheep's growth performance at different times. Therefore, this current study focused on sheep's nutrient apparent digestibility, feed efficiency, body index, and growth hormone when they are fed with low and high levels of B. decumbens diets. A total of 30 six-month-old male Dorper cross sheep were divided randomly into three treatment groups with 10 sheep per treatment. Treatment 1 (control) sheep were fed with Pennisetum purpureum and pellets as the basal diet, whereas Treatment 2 and 3 sheep were fed with feed mixed with low (10%) and high (60%) levels of B. decumbens, respectively. The study was conducted in two phases consisting of short-term feeding (seven days) and long-term feeding (90 days). Throughout the experiment, daily fecal voided were collected in the morning for seven days continuous before the end of each feeding phases for the determination of nutrient apparent digestibility. The amount of feed offered and refusals plus body weight gain were recorded daily to determine the feed efficiency (FE). Besides, the body measurements of each sheep from every treatment were measured weekly and blood samples were collected for the analysis of growth hormone (GH) concentration. There were significant differences (p < 0.05) in the nutrient apparent digestibility, growth performance, body measurement, and GH concentration among treatment sheep throughout the study period. Treatment 3 sheep fed with 60% of B. decumbens diet revealed the lowest dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) digestibility during the long-term feeding. Likewise, Treatment 3 (T3) sheep had the lowest total bodyweight gain, average daily gain, total feed intake, and daily feed intake among treatment sheep. The heart girth index (HGI) of T3 sheep was also significantly lower during the short-term feeding. Moreover, the GH concentration of T3 sheep was significantly lower as compared to the control that decreases steadily throughout the study period. In conclusion, high levels of B. decumbens showed the most significant results out of all three treatments indicating the presence of saponins, which produce negative effects on the sheep's overall performance.

Freeze-process has been applied in preserving many fresh horticultural commodities addressed to the medium-distancing distribution. In this study, effect of freezing process and storage time on durian's attributes degradation was observed. 100 durian fruits were treated with two-level combinations of freezing process. The first level involves the freezing of the said fruit at -15°C for two different freezing times, that is 10 min (treatment A) and 20 min (treatment B). Followed by frozen-storage for -10°C for 0, 10, 20 and 30 days. At different interval time, the frozen samples were thawed at 4°C for 24h. Then, physical, chemical, and sensory parameters were periodically assessed. The result showed that treatment B provide a significantly better output than treatment A. This is proven through a lower weight loss, brighter and lighter yellow of the pulp, softer pulp, lower value of moisture content on the pulp, and a remained stable of succinate acid's profile. Furthermore, based on the preference evaluation test, the fruits were accepted by respondents.