Embryology of Maldives Clownfish, Amphiprion nigripes (Amphiprioninae)

This study investigated the embryonic development of Maldives clownfish Amphiprion nigripes under natural conditions (28 - 30℃) at a lagoon of Agatti Island, Lakshadweep, India. The newly deposited fish egg was capsule-shaped and orange-red, with a (0.73 ± 0.04) mm3 yolk containing 5 - 10 fat globules. The embryonic development of fertilized eggs was divided into 26 stages and the time elapsing for each stage was recorded. Results showed that the cleavage was rapid, with the first division observed 1 h 20 min after fertilization. Blastulation occurred 4 h later, followed by gastrulation 12 h after fertilization, with a yolk volume of (0.61 ± 0.06) mm3. The organogenesis process started 22 h after fertilization when the blastopores closed and notochord formation began. The embryonic stage was recorded 24 h later, with the appearance of forebrain, midbrain, hindbrain, melanophores on yolk-sac and 22 somites, and a decreased yolk volume of (0.54 ± 0.08) mm3. Other organs developed well 31 h after fertilization, whereas the heart started beating and blood circulation began 78 h later. Red pigmentation (erytrophores) appeared 96 h after fertilization, with a small yolk volume of (0.22 ± 0.02) mm3. Mouth developed well and eyes were noticeable 120 h later, with head, pectoral fin and tail frequently moving 144 h after fertilization. The embryo reached the pre-hatching stage 168 h later and started to hatch after 170 - 180 h incubation. This study first detailed the embryonic development and yolk absorption of A. nigripes under natural conditions.

Coral Reef Bleaching at Agatti Island of Lakshadweep Atolls,India

A survey on coral bleaching was carried out at Agatti Island of Lakshadweep from May to June 2010.Elevated sea surface temperatures(SSTs)of the region exceeded the seasonal average and delayed the onset of monsoon,which triggered widespread bleaching of corals.The Agatti reefs showed an average of 73%bleached corals with apparent bleaching-related mortality of sea anemones(87%)and giant clams(83%).The SST increased up to 34℃with an average maximum SST of 32.5℃ during the study period between May and June 2010.Coral reefs on the southern side of the island are fully or partially exposed to sun light during low tide in contrast to the other side.This suggests that the mortality is more likely due to the low tide exposure than exclusively due to the elevated SST.Observations indicated a clear increase in coral bleaching during April 2010,at levels higher than that in normal summer.

Antibacterial and antioxidant effects from seaweed,Sargassum wightii(Greville,1848)against marine ornamental fish pathogens

Objective:To screen seaweed Sargassum wightii(S.wightii)for bioactive natural substance against marine ornamental fish bacterial pathogens,and also study the antioxidant properties,brine shrimp toxicity effect.Methods:Crude extract was made using three solvents(acetone,ethanol and methanol)and screened for antibacterial activity and purified by column chromatography,purified fractions obtained were tested for the activity.The 1st fraction of acetone extract showed maximum activity,this was again subjected for purification and obtained three sub-fractions also tested for the activity.Total phenols and flavonoid contents,reducing power,free radical scavenging activities(DPPH and H_(2)O_(2))and brine shrimp toxicity were also studied using purified acetone extract followed by standard methods.Results:The purified acetone extract showed maximum activity against eight pathogens among ten.GC-MS results revealed two major compounds such as 24-methylene cholesterol(79.9%)and methyl oleate(30.3%)which presented in higher percentage in purified extract and had highest phenols and flavonoid contents,reducing power,free radical scavenging activities,and also showed less toxicity effect.In he present study,the purified extract of S.wightii had potential antibacterial activity against Aeromonas hydrophila[(22.25±0.35)mm]and minimum activity against Streptococcus sp.[(10.00±0.00)mm].The purified extract of S.wightii also had potential total antioxidant activity of(3.87±0.04)μg at 100μg/mL concentration and the lowest activity was exhibited(1.52±0.01)μg at 25μg/mL.Conclusions:The present study concluded that the brown seaweed,S.wightii has potential antimicrobial and antioxidant activities,which can be used in aquaculture industry for treated bacterial diseases in infected fishes.

In vitro antibacterial activity of venom protein isolated from sea snake Enhydrina schistosa against drug-resistant human pathogenic bacterial strains

Objective:To evaluate the antibacterial activity of sea snake(Enhydrina schistosa)venom protein against drug-resistant human pathogenic bacterial strains.Methods:The venom was collected by milking process from the live specimens of sea snake are using capillary tubes or glass plates.Venom was purified by ion exchange chromatography and it was tested for in-vitro antibacterial activity against 10 drug-resistant human pathogenic bacterial strains using the standard disc diffusion method.Results:The notable antibacterial activity was observed at 150μg/mL concentration of purified venom and gave its minimum inhibitory concentrations values exhibited between 200-100μg/mL against all the tested bacterial strains.The maximum zone of inhibition was observed at 16.4 mm against Salmonella boydii and the minimum activity was observed at 7.5 mm against Pseudomonas aeruginosa.After the sodium-dodecyl-sulfate-polyacrylamide gel electrophoresis there were a clear single band was detected in the gel that corresponding to purified venom protein molecular weight of 44 kDa.Conclusions:These results suggested that the sea snake venom might be a feasible source for searching potential antibiotics agents against human pathogenic diseases.