Diabetes mellitus (DM) is known to cause reproductive impairment. In men, it has been linked to altered sperm quality and testicular damage. Oxidative stress (OS) plays a pivotal role in the development of DM complications. Glutathione (GSH) is a part of a nonenzymatic antioxidant defense system that protects lipid, protein, and nucleic acids from oxidative damage. However, the protective effects of exogenous GSH on the male reproductive system have not been comprehensively examined. This study determined the impact of GSH supplementation in ameliorating the adverse effect of type 1 DM on sperm quality and the seminiferous tubules of diabetic C57BL/6NTac mice. GSH at the doses of 15 mg kg −1 and 30 mg kg −1 was given intraperitoneally to mice weekly for 6 consecutive weeks. The mice were then weighed, euthanized, and had their reproductive organs excised. The diabetic (D Group) showed significant impairment of sperm quality and testicular histology compared with the nondiabetic (ND Group). Diameters of the seminiferous lumen in diabetic mice treated with 15 mg kg −1 GSH (DGSH15) were decreased compared with the D Group. Sperm motility was also significantly increased in the DGSH15 Group. Improvement in testicular morphology might be an early indication of the protective roles played by the exogenous GSH in protecting sperm quality from effects of untreated type 1 DM or diabetic complications. Further investigation using different doses and different routes of GSH is necessary to confirm this suggestion.

Vitrification is an important tool to store surplus embryos in assisted reproductive technology (ART). However, vitrification increases oxidative damage and results in decreased viability. Studies have reported that L-glutathione (GSH) supplementation improves the preimplantation development of murine embryos. Glutathione constitutes the major non-protein sulphydryl compound in mammalian cells, which confers protection against oxidative damage. However, the effect of GSH supplementation on embryonic vitrification outcomes has yet to be reported. This study aims to determine whether GSH supplementation in culture media improves in vitro culture and vitrification outcomes, as observed through embryo morphology and preimplantation development. Female BALB/c mice aged 6–8 weeks were superovulated through an intraperitoneal injection of 10 IU of pregnant mare serum gonadotrophin (PMSG), followed by 10 IU of human chorionic gonadotrophin (hCG) 48 h later. The mated mice were euthanized by cervical dislocation 48 h after hCG to harvest embryos. Two-cell embryos were randomly assigned to be cultured in either Group 1 (GSH-free medium), Group 2 (GSH-free medium with vitrification), Group 3 (0.01 mM GSH-supplemented medium), or Group 4 (0.01 mM GSH-supplemented medium with vitrification). Non-vitrified (Groups 1 and 3) and vitrified (Groups 2 and 4) embryos were observed for morphological quality and preimplantation development at 24, 48, 72, and 96 h. In the non-vitrified groups, there were significant increases in the number of Grade-1 blastocysts in GSH cultures (p < 0.05). Similarly, in the vitrified groups, GSH supplementation was also seen to significantly increase blastocyst formation. Exogenous GSH supplementation resulted in a significant increase in intracellular GSH, a release of cytochrome c from mitochondria, and a parallel decrease in intracellular reactive oxygen species (ROS) levels in vitrified eight-cell embryos (p < 0.05). GSH supplementation was shown to upregulate Bcl2 expression and downregulate Bax expression in the vitrified preimplantation embryo group. The action of exogenous GSH was concomitant with an increase in the relative abundance of Gpx1 and Sod1. In conclusion, our study demonstrated the novel use and practical applicability of GSH supplementation for improving embryonic cryotolerance via a decrease in ROS levels and the inhibition of apoptotic events by improvement in oxidative status.

Since there was a lack of study on the diversity and genetics of marine fishes in Pulau Tinggi, Mersing, Johor could be found to date, this study was conducted to provide a baseline data of species checklist of marine fishes in Pulau Tinggi and to obtain DNA barcodes of the fish specimens using cytochrome c oxidase subunit I (COI) gene. Sample collection in this study was conducted starting from July to August 2019. Spinning rod (angling), hand-net (manual sampling) and gillnet (mid-water column) were used as sampling methods in this study. All specimens obtained in this study were first identified based on morphological features, followed by a molecular approach for unidentified individuals. The morphological and molecular classification proved that all 183 individuals of marine fishes obtained in this study belonged to 83 species, 58 genera, 36 families, 9 orders and 2 classes. Among 83 species obtained in this study, 74 (89%) possess important values for human use. According to IUCN Red List online platform, 22 species are classified as Not Evaluated (NE), one species is classified as Data Deficient (DD), 56 species are classified as Least Concern (LC), three species are classified as Near Threatened (NT) and the remaining one species is classified as vulnerable (VU). A total of seven bidirectional CO1 barcode sequences were obtained from seven species, six genera and six families. All the sequences obtained have significant E values, which were zero, with percent identity values being more than 98% and query coverage values being more than 89%. The blast results for all the sequences provided correct identification until the species level. For future research, this study has updated the latest checklist of marine fishes from Pulau Tinggi, Mersing, Johor, Malaysia.

The effects of vitrification and slow-freezing on mitochondrial functions of in vitro produced murine embryos at various developmental stages were investigated using the Confocal Laser Scanning Microscope (CLSM). Oocytes were obtained from superovulated females, fertilized with sperm and cultured. Resulting 2-, 4- and 8-cell embryos were collected and cryopreserved by vitrification and slow-freezing. Mitochondria were stained with MitoTracker Red (CMXRos). Images were viewed by CLSM and analyzed using QWin SoftwareV.3. Fluorescent intensities were used to indicate viability. Results showed that mitochondrial fluorescence intensities of cryopreserved embryos were significantly lower as compared to non-cryopreserved embryos (p<0.01). Vitrification was found to be superior to slow-freezing at all developmental stages, based on mitochondrial function.

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There is still a lack of data on the species presence of sea cucumbers in Pulau Tinggi, Johor. Therefore, this study aimed to document the species checklist of sea cucumbers (Phylum Echinodermata: Class Holothuroidea) in Pulau Tinggi, Johor, Malaysia. The live sea cucumbers were collected for approximately two months from August 2019 to September 2019 during low tide. A total of ten species of sea cucumbers representing one order and two genera were documented. Among the total number of sea cucumbers collected from Pulau Tinggi, five species were under the Holothuria while another five belonged to the genus Stichopus. In Pulau Tinggi, Holothuria (Mertensiothuria) leucospilota (Brandt, 1835) was found to be the most prevalent species as it was documented and observed at all sampling sites. Furthermore, semi-structured interviews involving 15 respondents were incorporated during the data collection to obtain more information about the sea cucumber species. This study has contributed to the latest update on the list of sea cucumber species in Pulau Tinggi, as well as more updates related to the benefits of the sea cucumber to the residents, the environmental issues, the management and the conservation of sea cucumber in Pulau Tinggi.

Cephalopods are one of the protein sources in fisheries and their unique look inspires humans in many aspects from arts to engineering. However, there was a lack of studies on cephalopod species presence and genetics in Malaysia especially in the waters of Johor. Therefore, this study aimed to document the species checklist of coastal cephalopods in Pulau Tinggi, Mersing, Johor. The sampling was limited to the coastal area of Kampung Tanjung Balang, Pulau Tinggi. The specimens of cephalopods were obtained through handpicking (for the octopus) and from the local people (for the squids). In this study, the initial species identification of the cephalopod specimens was done based on their morphological characteristics. Their tissue samples were then prepared for DNA sequencing for further species identification using cytochrome c oxidase I (COI) gene sequences. The morphological identification and the Basic Local Alignment Search Tool (BLAST) analysis results suggested their species status as Octopus laqueus, Sepioteuthis lessoniana and Uroteuthis (Photololigo) chinensis. In conclusion, this study has contributed to the latest update on the checklist of cephalopod species in Pulau Tinggi. Furthermore, adding the COI gene sequences of the local cephalopods in the GenBank database (Accession No.: MN711655-MN711658) will act as a new resource for future research on cephalopod species.