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The research assessed the inclusion of MRD-Pro®, a bacterial-derived single-cell protein (SCP), in the diets of Nile tilapia (Oreochromis niloticus) fry with an initial weight of 0.12 grams. Using a diet composed of 45% crude protein and 14% crude fat, with an initial fishmeal content of 8.0% (designated as Diet 0.00% SCP, the control), SCP replaced 50% and 100% of the fishmeal on a protein basis, incorporated at levels of 4.25% and 8.50%, respectively. In addition, two more diets were prepared with higher levels of SCP, 14.50% and 21.00%. All diets were isoproteic and isolipidic. Weight gains of fish fed with the control diet (27.26 g) and the 4.25% SCP diet (21.61 g) were statistically comparable among themselves but were significantly greater than those of fish fed the 8.50% SCP (10.45 g), 14.50% SCP (11.54 g), or 21.00% SCP (7.28 g) diets, a trend observed across all growth and feed utilization indices. Increasing dietary SCP significantly reduced the crude fat and dry matter content in fish muscle tissue, while minimal changes in the amino acid profile of fish muscle tissue were observed. The bacterial-based SCP MRD-Pro® is a nutritious feed additive that can be effectively incorporated, within limits, into the diet of tilapia fry.

By-products from finfish processing from fisheries and aquaculture are often discarded. However, the enzymatic content of viscera has potential biotechnological and industrial applications. Such is the case for the sciaenids Cynoscion othonopterus, Cynoscion xanthulus, and Cynoscion parvipinnis, which are food and game fishes from the Gulf of California and whose viscera are commonly discarded after fish dressing. In this study, optimum temperature and pH for activity, as well as molecular weights of pepsin from the stomach of C. othonopterus, C. xanthulus, and C. parvipinnis were evaluated for the first time. Pepsin molecular weights were 30, 32.1, and 32.3 kDa, respectively. The highest activity of pepsin against hemoglobin was recorded between 40 and 45ºC for C. othonopterus and C. xanthulus and at 40°C for C. parvipinnis. The optimum pH was 2.0 for the three sciaenids. Biochemical characteristics were comparable to pepsins from other marine and freshwater fish species, so they could likely be used in some processes using this enzyme, like collagen extraction, fish silage production, or fish processing, among others.

Pyridine, a compound with a heterocyclic structure, is a key player in medicinal chemistry and drug design. It is widely used as a framework for the design of biologically active molecules and is the second most common heterocycle in FDA-approved drugs. Pyridine is known for its diverse biological activity, including antituberculosis, antitumor, anticoagulant, antiviral, antimalarial, antileishmania, anti-inflammatory, anti-Alzheimer's, antitrypanosomal, antimalarial, vasodilatory, antioxidant, antimicrobial, and antiproliferative effects. This review, spanning from 2022 to 2012, involved the meticulous identification of pyridine derivatives with antiproliferative activity, as indicated by their minimum inhibitory concentration values (IC50) against various cancerous cell lines. The aim was to determine the most favorable structural characteristics for their antiproliferative activity. Using computer programs, we constructed and calculated the molecular descriptors and analyzed the electrostatic potential maps of the selected pyridine derivatives. The study found that the presence and positions of the -OMe, -OH, -C=O, and NH2 groups in the pyridine derivatives enhanced their antiproliferative activity over the cancerous cellular lines studied. Conversely, pyridine derivatives with halogen atoms or bulky groups in their structures exhibited lower antiproliferative activity. [ABSTRACT FROM AUTHOR]

Trypsin and pancreatic lipase promote the digestion of proteins and lipids, respectively, when they are secreted into the anterior intestine; however, since the pancreas is a diffuse tissue in fish, the characterization and quantification of pancreatic enzymes is uncommon. The objective of this study was to partially characterize and compare the enzymatic activities of lipase and trypsin within the gastrointestinal tract of Cynoscion parvipinnis, Cynoscion othonopterus and Cynoscion xanthulus, to contribute to the knowledge of the digestive physiology of these important commercial sciaenids and to reveal whether they have potential for biotechnological applications. The presence of lipase and trypsin was confirmed by zymography and the molecular weights of both enzymes were determined by electrophoresis. For lipase, molecular weights of 65.8 and 69.5 kDa were determined for C. othonopterus and C. xanthulus, respectively. For C. parvipinnis, two lipases of 61.5 and 36.0 kDa were determined. In all three species the largest lipase activity was observed in the anterior intestine, followed by pyloric caeca, with optimum activity observed at pH 8.0 and at temperatures ranging between 40 and 45°C. Molecular weights of trypsin were 24.4, 23.6 and 23.7 kDa in C. othonopterus, C. parvipinnis, and C. xanthulus, respectively. The optimum pH of activity ranged between 7.0 and 9.0 and optimum temperature between 55 and 65°C for all species. These enzymes meet certain criteria that make them potential candidates for some industrial applications, such as the food industry and the production of detergents.

Limbaugh’s damselfish, Chromis limbaughi Greenfield & Woods, 1980, is endemic to the Gulf of California, and one of the five most exploited species for the aquarium trade in this region. C. limbaughi is a gonochoristic, gregarious and territorial species without sexual dimorphism that inhabits rocky, sheltered areas. Development of captive breeding techniques for this species would not only ensure a continued supply of fish for the commercial trade, but perhaps more importantly, it would also alleviate fishing pressure and support stock enhancement. Thus, as a first step towards achieving these goals, in this work, we investigated some aspects of the reproductive biology of C. limbaughi. Seasonal fish samplings, with a total of eighty-nine fish caught in one year, were carried out at San Esteban Island, Gulf of California, Mexico. The reproductive season of C. limbaughi extends, at least, from May to September. A new maximum standard length of 10.5 cm is reported for this species. The estimated size at first sexual maturity was 7.90 cm for males and 7.59 cm for females. For both male and female gonads, the major constituent fatty acids were palmitic acid, stearic acid, oleic acid, docosahexaenoic acid, eicosapentaenoic acid and arachidonic acid. The water-quality conditions under which maturation of C. limbaughi took place were measured, and should prove useful for the management of broodstock in captivity.

Lipids are one of the main macronutrients that constitute balanced feeds used in aquaculture. Adequate utilization of dietary lipid is influenced by the activity of pancreatic lipase, one of the enzymes that promotes digestion of dietary lipids in the gastrointestinal tract of fish. The culture of Totoaba macdonaldi is quite recent; its nutritional requirements have been partially established. Knowing the characteristics of pancreatic lipase for this species could help optimize the dietary lipids included in balanced feeds for its culture. Therefore, the aim of this work is to partially characterize and evaluate the enzymatic activity of pancreatic lipase for T. macdonaldi. Biological indices showed that experimental organisms had a good nutritional status. Pancreatic lipase molecular weight was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and its activity was evaluated in crude enzymatic extracts from different gastrointestinal tract regions. The molecular weight of lipase was estimated to be 70.4 kDa; the highest lipolytic activity was observed at 45°C and at a pH optimum of 8.0 in the anterior intestine and pyloric caeca, where the concentration and activity of the enzyme was significantly higher (P=0.004) compared to the distal parts of the intestine. Biochemical characteristics observed for the pancreatic lipase of T. macdonaldi are quite similar to other lipases of fish cultured worldwide; results provided in this study will help understand the role this lipolytic enzyme plays in the digestive process of this species.

Cynoscion parvipinnis is an important fisheries resource of the Gulf of California used locally for human consumption. Its aquaculture potential has recently been demonstrated, and cultured organisms are already available. In this study, the gonadal developmental stage, proximate composition, fatty acid profile and other biochemical and biological indices of wild and cultured fish were characterized. A total of 80 fish, 30 cultured (15 female and 15 male) and 50 wild (31 female and 19 male), captured in November at Santa Rosa, Sonora, Mexico, were analyzed. Histological analyses of the gonads showed that 100% of the wild and cultured fish were at an early maturation stage. Wild fish had greater body weight, total length and gonadosomatic index. Cultured female fish (19.64%) possessed a slightly higher protein content in their gonads than wild females (17.11%), whereas males had similar values (14.00 and 14.83%). Cultured females (10.85%) and males (20.48%) had a significantly greater crude fat content than wild fish (female: 2.05%, male: 11.05%). Palmitic acid was the most abundant fatty acid (FA), ranging from 128.58-164.84 mg of 16:0 g-1 of gonad wet weight. After 16:0, highly unsaturated FAs like DHA, ARA and EPA were the major FA in gonadal tissue; n-3 FAs were quantitatively higher than n-6 FAs, while the n-3/n-6 ratios ranged from 2.08-2.81. In general, the biochemical composition of the gonad of wild and cultured organisms at an early maturation stage was quite similar. These data may serve as indicators of dietary requirements for a maturation diet for broodstock culture.

Juveniles of wild Pacific blue shrimp Litopenaeus stylirostris (mean initial weight ± standard deviation = 1.5 ± 0.1 g) were acclimated from a natural seawater salinity of 35‰ to salinities of 0, 2.5, 5.0, 7.5, 10, 15, and 25‰. After reaching the desired salinities, L. stylirostris were cultured for 32 d and growth, feed conversion ratio, and survival, as well as hemolymph and culture water osmolality, were determined. The L. stylirostris exposed to 0‰ died before or shortly after reaching the salinity end point. Final mean body weight of L. stylirostris held at 2.5‰ (3.1 ± 0.8 g) was significantly reduced compared with all other treatments. In contrast, those held at salinities from 5‰ to 35‰ had similar performance, with mean body final weight ranging from 3.8 to 4.5 g, showing that L. stylirostris can be cultured across this range of salinities without adversely affecting growth, survival, or feed conversion ratio. Litopenaeus stylirostris is a euryhaline organism, able to maintain its hemolymph osmolality relatively constant despite changes in salinity. The isosmotic salinity of L. stylirostris, estimated from the point of intersection between the regression lines of water salinity versus water osmolality and water salinity versus hemolymph osmolality, was 26.7‰. Litopenaeus stylirostris is an efficient osmoregulator with potential for low‐salinity culture. [ABSTRACT FROM AUTHOR]

Limbaugh's damselfish, Chromis limbaughi Greenfield & Woods, 1980, is endemic to the Gulf of California, and one of the five most exploited species for the aquarium trade in this region. C. limbaughi is a gonochoristic, gregarious and territorial species without sexual dimorphism that inhabits rocky, sheltered areas. Development of captive breeding techniques for this species would not only ensure a continued supply of fish for the commercial trade, but perhaps more importantly, it would also alleviate fishing pressure and support stock enhancement. Thus, as a first step towards achieving these goals, in this work, we investigated some aspects of the reproductive biology of C. limbaughi. Seasonal fish samplings, with a total of eighty-nine fish caught in one year, were carried out at San Esteban Island, Gulf of California, Mexico. The reproductive season of C. limbaughi extends, at least, from May to September. A new maximum standard length of 10.5 cm is reported for this species. The estimated size at first sexual maturity was 7.90 cm for males and 7.59 cm for females. For both male and female gonads, the major constituent fatty acids were palmitic acid, stearic acid, oleic acid, docosahexaenoic acid, eicosapentaenoic acid and arachidonic acid. The water-quality conditions under which maturation of C. limbaughi took place were measured, and should prove useful for the management of broodstock in captivity. [ABSTRACT FROM AUTHOR]

The article offers information on a study related to growth performance of totoaba in accordance with feed utilization and dietary lipids. Topics discussed include totoaba breeding programmes, calculation of daily feed ration based on the individual mean weight, and parameters for growth performance evaluation including weight gain, daily weight gain and percent weight gain.