Variation in ligand responses of the bitter taste receptors TAS2R1 and TAS2R4 among New World monkeys.

BACKGROUND: New World monkeys (NWMs) are unique in that they exhibit remarkable interspecific variation in color vision and feeding behavior, making them an excellent model for studying sensory ecology. However, it is largely unknown whether non-visual senses co-vary with feeding ecology, especially gustation, which is expected to be indispensable in food selection. Bitter taste, which is mediated by bitter taste receptors (TAS2Rs) in the tongue, helps organisms avoid ingesting potentially toxic substances in food. In this study, we compared the ligand sensitivities of the TAS2Rs of five species of NWMs by heterologous expression in HEK293T cells and calcium imaging. RESULTS: We found that TAS2R1 and TAS2R4 orthologs differ in sensitivity among the NWM species for colchicine and camphor, respectively. We then reconstructed the ancestral receptors of NWM TAS2R1 and TAS2R4, measured the evolutionary shift in ligand sensitivity, and identified the amino acid replacement at residue 62 as responsible for the high sensitivity of marmoset TAS2R4 to colchicine. CONCLUSIONS: Our results provide a basis for understanding the differences in feeding ecology among NWMs with respect to bitter taste

A tribute to Ei Horikoshi (1932-2009)

Masaaki Shimizu, Shigeru Otoh, and Nigel J. Coo

Comparative Study of Inducing Broodstock with Natural and Artificial Hormones on Reproductive Performances of Clarias gariepinus

This study was conducted to investigate the effects of artificial and natural hormones (ovaprim and pituitary extract) on the reproductive performances of Clarias gariepinus (African catfish). A total of twenty brood stock, 12 males and 8 females with mean weight of 2.0 kg each were selected for breeding following the external morphological characteristics and standard breeding procedure. The water parameters for indoor culture tanks during the study were optimal for breeding: pH 7.31; temperature, 27.6˚C. Dissolved oxygen, 5.18 mg L-1. The result revealed no significant (P > 0.05) differences in water quality parameters between the culture tanks for artificial and natural hormonal applications during the study. The percentage fertilization, hatchability, survival and fry production success were: 89.23%, 93.31%, 87.16% and 69.41%; and 79.02%, 72.56%, 67.32% and 34.67% respectively, for pituitary extract and Ovaprim®. Pituitary extract recorded higher values and significantly performed better (P < 0.05) between the two treatments.  This indicates that natural hormone (pituitary extract) is equally effective and therefore recommended   for   the   artificial   propagation   of Clarias gariepinus

Effect of Different Ages of African catfish (Clarias gariepinus) Broodstock on Reproductive Performance and Fries Production

This study was conducted at the hatchery complex of Akwa Ibom State University to investigate the effect of different ages of African catfish (Clarias gariepinus) on their reproductive performances. Eighteen (18) broodstock of Clarias gariepinus (3 males and 3 females) from each age group, six months, twelve months and eighteen months old with average body measurement of 1.1kg and 32cm for six month, 1.8kg and 43cm for 12 months and 2.5 kg and 65.7cm for 18 months were selected from AKSU fish farm labeled treatment A, B and C for the study. 3 male broodstock from each treatment were sacrificed for milt extraction without hormonal inducement. The milt from each treatment were separately pooled into one volume and divided into three portions each diluted with 2ml of normal saline solution. Three female broodstock from each treatment were separately induced with ovaprim at a single dosage of 0.5ml/kg body weight of fish and allowed for a latency period of ten hours at water temperature of 26oC before stripping manually. 3g of egg from each broodstock was mixed with the diluted milt and activated with 100 mls of normal saline. The fertilized eggs were incubated in aerated indoor concrete tanks in 3 replicates. % fertilization were accessed six (6) hours after incubation, % hatchability was accessed twenty-six hours (26) after incubation, while the percentage survival and fry production success in each treatment was accessed after ten (10) days post hatching. The results reveal that the reproductive parameters considered in this study significantly (p<0.05) increased with age of broodstocks. The percentage fertilization of egg from the least to the oldest broodstock were 63.67± 0.88, 69.50 ± 0.87 and 81.83 ± 5.05 respectively. The percentage hatchability of the oldest broodstock was 82.62 ± 1.6 significantly (P< 0.05) higher than 64.79 ± 2.74 (12 months) with the least value of 49.04 ± 5.76 recorded for six-month-old broodstock. The oldest broodstock had the highest percentage survival 83.14 ± 3.16 and fry production success of 56.05± 0.06 while the least broodstock (6-month-old) had the least value of survival 54.59 ± 2.42 and fry production success of 17.17 ± 2.59%