Subterranean Waters of Yucatán Peninsula, Mexico Reveal Epigean Species Dominance and Intraspecific Variability in Freshwater Ostracodes (Crustacea: Ostracoda)

The Yucatán Peninsula is a karstic region, rich in subterranean environments with a diverse crustacean stygobiont fauna. In order to gain insights into the biological evolution of the subterranean environments of this region, we evaluated the ostracode species composition of caves and cenotes in five independent sampling campaigns (2008, 2013, 2017–2019). Using morphometric analyses, we evaluated inter-population morphological variability; using molecular analysis based on mitochondrial COI and nuclear 18S rDNA, we evaluated genetic differentiation in selected species. The observed fauna is composed of 20 (epigean) species, presenting a lack of strict stygobionts. Morphometric analyses discriminated up to three morphotypes in each of the three most abundant species: Cytheridella ilosvayi, Alicenula sp. and Cypridopsis vidua. High intraspecific morphological variability was found either in shape or size. Phylogenetic analysis based on COI demonstrated the existence of three lineages on C. ilosvayi, with high support (>0.9). The 18S rDNA sequences were identical among individuals of different populations. A lack of congruence between the genetic markers precluded us from postulating speciation in subterranean environments. It is likely that Late Pleistocene—Early Holocene climate variation related to sea level and precipitation was forcing agent for epigean ostracode dominance in subterranean environments of the Peninsula

Topography and coral community of the Sisal Reefs, Campeche Bank, Yucatán, México

The Campeche Bank, Gulf of Mexico, is a region with abundant coral reef ecosystems that havent been studied despite providing goods and services to some human communities. This work presents the topography, coral community and conspicuous reef associated fauna of three reefs of this region: Sisal, Madagascar and Serpiente. Three-D models of reef topography were derived using a GPS-echo-sounder coupled with geostatistical methods. The coral community was assessed through composition, richness, density and size of the colonies. The size of the Sisal Reefs was bigger than other Gulf of Mexico reefs. Hard coral colonies presented an average diameter of 9 cm and an average density of 9 colonies/m2 , whereas octocoral colonies averaged 11 cm in height and presented an average density of 24 colonies/m2 . We found 18 hard coral and 14 octocoral species, all of them distributed in the Atlantic Ocean; however, this work is the first to report Carijoa riseii and Phyllangia americana for the Mexican reefs of the Gulf of Mexico. The conspicuous fauna consisted in species with aquaculture potential (e.g. Octopus maya, Panulirus argus, Periclimenes pedersoni) and conservation priority (i.e. Eretmochelys imbricata). This study shows that these reefs are important centers of marine life and provides a baseline for future research

Feeding habits of the dwarf weakfish (Cynoscion nannus) off the coasts of Jalisco and Colima, Mexico

Sciaenids from the Pacific coast of Mexico are used as a second-class fish species for human consumption (Aguilar-Palomino et al., 1996). The dwarf weakfish (Cynoscion nannus) (Castro-Aguirre and Arvizu-Martínez, 1976) is often caught as bycatch in the shrimp fishery but, because of its small size (<27 cm TL, total length), it is not considered a valuable resource. This species can be found in great numbers in waters between 100 and 812 m (Allen and Robertson, 1994; Fischer et al., 1995) associated with the soft-bottom regions off the coast of Jalisco and Colima (González-Sansón et al., 1997)

Comparison of Aerobic Scope for Metabolic Activity in Aquatic Ectotherms With Temperature Related Metabolic Stimulation: A Novel Approach for Aerobic Power Budget

Considering that swim-flume or chasing methods fail in the estimation of maximum metabolic rate and in the estimation of Aerobic Scope (AS) of sedentary or sluggish aquatic ectotherms, we propose a novel conceptual approach in which high metabolic rates can be obtained through stimulation of organism metabolic activity using high and low non-lethal temperatures that induce high (HMR) and low metabolic rates (LMR), This method was defined as TIMR: Temperature Induced Metabolic Rate, designed to obtain an aerobic power budget based on temperature-induced metabolic scope which may mirror thermal metabolic scope (TMS = HMR—LMR). Prior to use, the researcher should know the critical thermal maximum (CT max) and minimum (CT min) of animals, and calculate temperature TIMR max (at temperatures −5–10% below CT max) and TIMR min (at temperatures +5–10% above CT min), or choose a high and low non-lethal temperature that provoke a higher and lower metabolic rate than observed in routine conditions. Two sets of experiments were carried out. The first compared swim-flume open respirometry and the TIMR protocol using Centropomus undecimalis (snook), an endurance swimmer, acclimated at different temperatures. Results showed that independent of the method used and of the magnitude of the metabolic response, a similar relationship between maximum metabolic budget and acclimation temperature was observed, demonstrating that the TIMR method allows the identification of TMS. The second evaluated the effect of acclimation temperature in snook, semi-sedentary yellow tail (Ocyurus chrysurus), and sedentary clownfish (Amphiprion ocellaris), using TIMR and the chasing method. Both methods produced similar maximum metabolic rates in snook and yellowtail fish, but strong differences became visible in clownfish. In clownfish, the TIMR method led to a significantly higher TMS than the chasing method indicating that chasing may not fully exploit the aerobic power budget in sedentary species. Thus, the TIMR method provides an alternative way to estimate the difference between high and low metabolic activity under different acclimation conditions that, although not equivalent to AS may allow the standardized estimation of TMS that is relevant for sedentary species where measurement of AS via maximal swimming is inappropriate

Maturation trade-offs in octopus females and their progeny: energy, digestion and defence indicators

Sexual maturation and reproduction influence the status of a number of physiological processes and consequently the ecology and behaviour of cephalopods. Using Octopus mimus as a study model, the present work was focused in the changes in biochemical compound and activity that take place during gonadal maturation of females and its consequences in embryo and hatchlings characteristics. To do that, a total of 31 adult females of O. mimus were sampled to follow metabolites (ovaries and digestive gland) and digestive enzyme activities (alkaline and acidic proteases) during physiological and functional maturation. Levels of protein (Prot), triacylglyceride (TG), cholesterol (Chol), glucose (Glu), and glycogen (Gly) were evaluated. Groups of eggs coming from mature females were also sampled along development and after hatching (paralarvae of 1 and 3 days old) to track metabolites (Prot, TG, Glu, Gly, TG, Chol), digestive enzymes activity (Lipase, alkaline proteases, and acidic proteases), and antioxidant/detoxification defence indicators with embryos development. Based on the data obtained, we hypothesized that immature females store Chol in their ovaries, probably from the food they ingested, but switch to TG reserves at the beginning of the maturation processes. At the same time, results suggest that these processes were energetically supported by Glu, obtained probably from Gly breakdown by gluconeogenic pathways. Also, was observed that embryos metabolites and enzyme activities (digestive and antioxidant/detoxification enzymes) where maintained without significant changes and in a low activity during the whole organogenesis, meaning that organogenesis is relatively not energetically costly. In contrast, after organogenesis, a mobilization of nutrients and activation of the metabolic and digestive enzymes was observed, together with increments in consumption of yolk and Gly, and reduction in lipid peroxidation. Derived from our results, we also have the hypothesis that reactive oxygen species (ROS) were produced during the metabolic processes that occurs in ovarian maturation. Those ROS may be in part transferred to the egg provoking a ROS charge to the embryos. The elimination of ROS in embryos started when the activity of the heart and the absorption of the yolk around stages XIV and XV were evident. Altogether, these processes allowed the paralarvae to hatch with buffered levels of ROS and with the antioxidant defence mechanisms ready to support further ROS production derived from paralarvae higher life stage requirements (feeding and metabolic demands)

Physiological characterization of Typhlatya cave shrimps: linking habitat with aerobic metabolism

The anchialine environment is characterized by a vertical stratification of water masses with different salinities. Cave shrimps of the genus Typhlatya are widespread inhabitants of the aquifer in fresh, brackish, and marine groundwater. Here we describe physiological aspects of three of the most abundant and widespread Typhlatya species that thrive in the fresh and marine groundwater habitats of the anchialine ecosystem of the Yucatan Peninsula. The aerobic scope (AS) of Typhlatya mitchelli, Typhlatya pearsei and Typhlatya dzilamensis was estimated through induced physical activity, whilst monitoring protein carbonylation and lipid peroxidation (as indicators of cellular damage), lactate accumulation (as an indicator of anaerobic metabolism) and the antioxidant system response. The critical thermal limits (CTL) of all three species as an additional measure of physiological plasticity were also determined. Our results showed that metabolic rates, AS and CTL were similar amongst the two species that inhabit fresh groundwater habitats, and differed markedly from T. dzilamensis, a species typically found in marine groundwater. The antioxidant system response in all three Typhlatya species accompanied the levels of aerobic metabolism following physical activity. However, the large amount of GSH observed in T. dzilamensis may be indicative of an adaptive trait to a more heterogeneous environment. The differences observed among Typhlatya species reflect different physiological adaptations that correspond to the environmental heterogeneity of their natural habitats. Our results suggest that the marine groundwater species, T. dzilamensis, could be better prepared to respond to a naturally more heterogeneous environment, in contrast to Typhlatya mitchelli and Typhlatya pearsei which rarely face environmental clines in the fresh groundwater habitat. Our findings contribute to a better understanding of the consequences of environmental change on ecologically important species that are restricted to live in the aquifer

Comparison of aerobic scope for metabolic activity in aquatic ectotherms with temperature related metabolic stimulation: a novel approach for aerobic power budget

Considering that swim-flume or chasing methods fail in the estimation of maximum metabolic rate and in the estimation of Aerobic Scope (AS) of sedentary or sluggish aquatic ectotherms, we propose a novel conceptual approach in which high metabolic rates can be obtained through stimulation of organism metabolic activity using high and low non-lethal temperatures that induce high (HMR) and low metabolic rates (LMR), This method was defined as TIMR: Temperature Induced Metabolic Rate, designed to obtain an aerobic power budget based on temperature-induced metabolic scope which may mirror thermal metabolic scope (TMS = HMR—LMR). Prior to use, the researcher should know the critical thermal maximum (CT max) and minimum (CT min) of animals, and calculate temperature TIMR max (at temperatures −5–10% below CT max) and TIMR min (at temperatures +5–10% above CT min), or choose a high and low non-lethal temperature that provoke a higher and lower metabolic rate than observed in routine conditions. Two sets of experiments were carried out. The first compared swim-flume open respirometry and the TIMR protocol using Centropomus undecimalis (snook), an endurance swimmer, acclimated at different temperatures. Results showed that independent of the method used and of the magnitude of the metabolic response, a similar relationship between maximum metabolic budget and acclimation temperature was observed, demonstrating that the TIMR method allows the identification of TMS. The second evaluated the effect of acclimation temperature in snook, semi-sedentary yellow tail (Ocyurus chrysurus), and sedentary clownfish (Amphiprion ocellaris), using TIMR and the chasing method. Both methods produced similar maximum metabolic rates in snook and yellowtail fish, but strong differences became visible in clownfish. In clownfish, the TIMR method led to a significantly higher TMS than the chasing method indicating that chasing may not fully exploit the aerobic power budget in sedentary species. Thus, the TIMR method provides an alternative way to estimate the difference between high and low metabolic activity under different acclimation conditions that, although not equivalent to AS may allow the standardized estimation of TMS that is relevant for sedentary species where measurement of AS via maximal swimming is inappropriate

Functional characterization of a GGPPS variant indentified in atypical femoral fracture patients and delineation of the role of GGPPS in bone-relevant cell types

Atypical femoral fractures (AFFs) are a rare but potentially devastating event, often but not always linked to bisphosphonate (BP) therapy. The pathogenic mechanisms underlying AFFs remain obscure, and there are no tests available that might assist in identifying those at high risk of AFF. We previously used exome sequencing to explore the genetic background of three sisters with AFFs and three additional unrelated AFF cases, all previously treated with BPs. We detected 37 rare mutations (in 34 genes) shared by the three sisters. Notably, we found a p.Asp188Tyr mutation in the enzyme geranylgeranyl pyrophosphate synthase, a component of the mevalonate pathway, which is critical to osteoclast function and is inhibited by N-BPs. In addition, the CYP1A1 gene, responsible for the hydroxylation of 17β-estradiol, estrone, and vitamin D, was also mutated in all three sisters and one unrelated patient. Here we present a detailed list of the variants found and report functional analyses of the GGPS1 p.Asp188Tyr mutation, which showed a severe reduction in enzyme activity together with oligomerization defects. Unlike BP treatment, this genetic mutation will affect all cells in the carriers. RNAi knockdown of GGPS1 in osteoblasts produced a strong mineralization reduction and a reduced expression of osteocalcin, osterix, and RANKL, whereas in osteoclasts, it led to a lower resorption activity. Taken together, the impact of the mutated GGPPS and the relevance of the downstream effects in bone cells make it a strong candidate for AFF susceptibility. We speculate that other genes such as CYP1A1 might be involved in AFF pathogenesis, which remains to be functionally proved. The identification of the genetic background for AFFs provides new insights for future development of novel risk assessment tools. © 2018 American Society for Bone and Mineral Research

Feeding habits of the fishes Lutjanus peru and Lutjanus guttatus (Pisces: Lutjanidae) of Guerrero, México.

Se analiza la composición de la dieta del huachinango (Lutjanus peru) y del flamenco (Lutjanus guttatus) en la costa de Guerrero, México. Los ejemplares se obtuvieron mensualmente de las capturas comerciales en tres regiones de pesca y presentaron intervalos de talla comprendidos entre 130 y 684 mm de longitud horquilla (LH) para el caso de L. peru, y de 120 a 550 mm para L. guttatus. A partir del número y del peso de los distintos componentes alimentarios, identificados hasta el taxon más bajo posible, se calcularon los porcentajes numéricos (%N), gravimétricos (%P) y de frecuencia de ocurrencia (%FO) que fueron sintetizados como valores de importancia relativa. En los estómagos de L. peru se identificaron 68 ítems alimentarios dentro de los cuales predominan los peces (%P = 50.9), los crustáceos (%P = 35.6) y los moluscos (%P = 7.2) mientras que el espectro alimentario de L. guttatus estuvo integrado por 88 componentes que incluyeron principalmente peces (%P = 50.8) y crustáceos (%P = 43.4). Ambas especies son depredadoras generalistas, con un amplio espectro de presas. Los valores de los índices de traslape de las dietas de estas especies sugieren que no existe un alto grado de competencia intraespecífica por el alimento. Con el fin de encontrar similitudes en la dieta de estos lutjánidos en varias localidades de México y Costa Rica, se realizó un análisis de conglomerados con los valores de importancia relativa de las presas, publicados en varios trabajos. Se encontró más afinidad en la dieta de aquellas especies que habitan en una misma localidad, que entre organismos de la misma especie distribuidos en diferentes zonas. Se infiere que la disponibilidad de las presas, más que la selectividad por el alimento, determina la dieta de estas especies.Diet composition of the Pacific snapper (Lutjanus peru) 130-684 mm fork length (FL) and the spotted snapper (Lutjanus guttatus) 120-550 mm FL, was analyzed. Monthly samples were obtained from commercial landings in three regions off the coast of Guerrero, Mexico. Percentage by number (%N), percentage by weight (%W), and percentage of occurrence (%O) were calculated for each prey and summarized as the index of relative importance. Both species are polyphagous predators feeding on a variety of prey: Sixty-eight prey items, mainly fish (%W = 50.9), crustaceans (%W = 35.6), and mollusks (%W = 7.2), were found in the stomach contents of L. peru, while 88 components were identified in the diet of L. guttatus, the most important prey being fish (%W = 50.8) and crustaceans (%W = 43.4). Diet overlap between species is not significant (p&lt;0.05), indicating that competition for food is unlikely. Based on published values of the relative importance index, the diets of these Lutjanidae were analyzed considering different regions of the Pacific coast of Mexico and Costa Rica, and similarities among sites and species were discussed. The cluster analysis showed that similarities among species inhabiting in the same area are more important than within organisms of the same species living in different zones. Results suggest that prey availability rather than food selectivity, conditions the feeding behavior of these fish species

Topography and coral community of the Sisal Reefs

ABSTRACT The Campeche Bank, Gulf of Mexico, is a region with abundant coral reef ecosystems that haven&apos;t been studied despite providing goods and services to some human communities. This work presents the topography, coral community and conspicuous reef associated fauna of three reefs of this region: Sisal, Madagascar and Serpiente. Three-D models of reef topography were derived using a GPS-echo-sounder coupled with geostatistical methods. The coral community was assessed through composition, richness, density and size of the colonies. The size of the Sisal Reefs was bigger than other Gulf of Mexico reefs. Hard coral colonies presented an average diameter of 9 cm and an average density of 9 colonies/m 2 , whereas octocoral colonies averaged 11 cm in height and presented an average density of 24 colonies/m 2 . We found 18 hard coral and 14 octocoral species, all of them distributed in the Atlantic Ocean; however, this work is the first to report Carijoa riseii and Phyllangia americana for the Mexican reefs of the Gulf of Mexico. The conspicuous fauna consisted in species with aquaculture potential (e.g. Octopus maya, Panulirus argus, Periclimenes pedersoni) and conservation priority (i.e. Eretmochelys imbricata). This study shows that these reefs are important centers of marine life and provides a baseline for future research. Key words: Conservation, corals, geostatistics, Gulf of Mexico, octocorals. RESUMEN El Banco de Campeche (Golfo de México) es una región con múltiples arrecifes de coral que proveen bienes y servicios a las comunidades humanas y varios de ellos aún no han sido estudiados todavía. Este trabajo presenta información preliminar ó pionera sobre la topografía, la comunidad coralina y la fauna conspicua, asociada de tres arrecifes de esta región: Sisal, Madagascar y Serpiente. La topografía se obtuvo realizando muestreos batimétricos y métodos geoestadísticos. La comunidad coralina se evaluó a través de la composición, riqueza, densidad y tamaño de las colonias de corales pétreos y octocorales. Los arrecifes estudiados presentaron tamaños superiores a otros arrecifes del Golfo de México. Las colonias de corales duros presentaron diametros de 9 cm en promedio y una densidad de 9 colonias/m 2 , mientras que las colonias de octocorales promediaron 11 cm de altura y una densidad de 24 colonias/m 2 . Se registraron 18 especies de corales duros y 14 de octocorales. Entre estas Carijoa riseii y Phyllangia americana no habían sido registradas en arrecifes mexicanos del Golfo de México. Algunas de las especies conspicuas presentan potencial en acuicultura (e.g. Octopus maya, Panulirus argus y Periclimenes pedersoni) o prioridad para su conservación (i.e. Eretmochelys imbricata). El estudio muestra que estos arrecifes son importantes centros de vida marina y provee la base para futuras investigaciones