Dendrobium Sabin Blue is an important orchid hybrid that has been grown extensively as cut flower, potted plant and is also popular for its deep purplish blue flowers. The most efficient long term conservation method of this hybrid is through cryopreservation. Cryopreservation involving the vitrification method consists of explants exposure to highly concentrated cryoprotective solution followed by freezing rapidly in liquid nitrogen. However, these treatments involved highly concentrated cryoprotectant that could incur toxicity to the explants. Hence, cryopreservation protocol requires biochemical analyses in understanding the damages or injuries occurred during cryopreservation treatments. In this study, biochemical analyses revealed a general reduction in chlorophyll, carotenoid and porphyrin content to 0.40 µg/g F W (thawing stage), 31.50 µg/g F W unloading stage and 2230.41 µg/g F W (thawing stage), respectively in comparison to the control treatments. In addition, increased level in proline content were obtained at different cryopreservation stages with highest level (5.42 µmole/g F W) recorded at the PVS2 dehydration stage. Fluctuated outcomes were obtained in catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POX) enzyme activities in PLBs exposed to different cryopreservation stages. Lowest values recorded for CAT enzyme activity were obtained at the dehydration stage (3.94 U/g). Lowest POX enzyme activities were obtained at the dehydration (122.36 U/g) and growth recovery (106.40 U/g) stages. Additionally, lowest APX enzyme activities values were recorded at the thawing (7.47 U/g) and unloading (7.28 U/g) stages. These have contributed to low regeneration of Dendrobium Sabin Blue protocorm like bodies (PLBs) following cryopreservation. Hence, in the future experimental design, exogenous antioxidant could be included in the cryopreservation procedures to improve the existing protocol.
In Malaysia, the aquaculture industry, particularly the production of freshwater aquaculture fish, is growing rapidly. Nevertheless, the illegal use of banned antimicrobial agents such as chloramphenicol in aquaculture has become a major concern in relation to the safety of consumers and also the development of drug-resistant strains in bacteria. Driven by those factors, the main intention of this study was to determine the prevalence and types of chloramphenicol resistance genes in E. coli isolated from aquaculture and other environmental waters. The respective chloramphenicol-resistance genes in the isolates were detected by multiplex PCR with four sense primers C-1, C-2, C-3, C-4 and one antisense primer C-R for targeting cat I, cat II, cat III and cat IV genes, respectively. Out of 27 E. coli isolated, 19 were resistant to chloramphenicol. Cat I, cat II, cat III and cat IV genes were detected in 19, 13, 10, and 6 of the E. coli isolates, respectively. The results of this study revealed that chloramphenicol-resistance E. coli is present in aquaculture and environmental waters, in the study area. This finding suggested that although banned, there could be illegal usage of chloramphenicol antibiotic in local aquaculture. The bacteria in aquaculture may have spread to other environmental water through disposal of aquaculture waste water to other environments.