Héctor Acosta-Salmón

Monoamine fluctuations during the reproductive cycle of the Pacific lion's paw scallop Nodipecten subnodosus

The Pacific lions paw scallop Nodipecten subnodosus has been one of the most important commercial species of mollusc in the Baja California peninsula in Mexico since 1990. This species is a functional hermaphrodite with tropical and sub-tropical distributions and experiences wide annual temperature oscillations influencing its physiological functions. We determined norepinephrine (NE), dopamine (DA), and serotonin (5-HT) concentrations in different organs (female and male gonads, digestive gland, adductor muscle, gill, mantle, and foot) of N. subnodosus, at 6 reproductive stages (resting, initial, maturing, mature, partially spent and fully spent). Monoamine concentrations were determined by HPLC fitted with an electrochemical detector. Results indicated that monoamine concentrations increased during maturing stage, peaked at mature stage and declined after spawning. NE concentrations were higher than the rest of monoamines followed by DA, and 5-HT. NE was present in all organs at all reproductive stages. DA concentrations were higher in the gill and digestive gland during all stages. 5-HT was only detectable in the male gonadic portion at all stages except at spent stage. NE was the most abundant neurotransmitter found in the female gonad of N. subnodosus, while 5-HT was the most abundant neurotransmitter found in the male gonad. Furthermore, these two neurotransmitters accumulated in the respective gonad tissues during the initial reproductive stages I to IV and then declined after spawning (stages V and VI). This suggests that this species utilized different neurotransmitters specific for each gender and that this utilization was related to the reproductive cycle.

Long-term biological effectiveness of Pochonia chlamydosporia var. catenulata against Meloidogyne incognita infection in a crop rotation systemi

ABSTRACT The aim of this study was to determine the effectiveness of Pochonia chlamydosporia var. catenulata and the bacteria Tsukamurella paurometabola strain C-924 (HeberNem™), to control Meloidogyne incognita infection in a crop rotation system (cucumber, tomato and pepper) under greenhouse production during six crop cycles. We determined gall index, prevalence, intensity of disease, and number of juvenile nematodes in soil. At the end of the sixth cycle, plants protected with P. chlamydosporia showed a reduction in gall index (≤2), prevalence, and median (42%) intensity of disease similar or more pronounced than those observed in plants protected with T. paurometabola (80%). Both treatments were more efficient at reducing galling than at reducing prevalence and therefore reduction of intensity of disease was mainly due to the reduction in galling. The hydrolytic activity of P. chlamydosporia and its resistant spores make this fungus one of the best options for the long-term control of RKNs by decreasing egg masses or galls. Pochonia chlamydosporia var. catenulata is an important part of a potential biological control strategy in rotation systems of vegetable crop and can be used for long-time IPM strategies in Cuba and the Caribbean.