UPRRP College of Natural Sciences

About: UPRRP College of Natural Sciences is a based out in . It is known for research contribution in the topics: Apoptosis & Population. The organization has 9323 authors who have published 11826 publications receiving 284172 citations.

Visual acuity in ray-finned fishes correlates with eye size and habitat.

Abstract: Visual acuity (the ability to resolve spatial detail) is highly variable across fishes. However, little is known about the evolutionary pressures underlying this variation. We reviewed published literature to create an acuity database for 159 species of ray-finned fishes (Actinopterygii). Within a subset of those species for which we had phylogenetic information and anatomically measured acuity data (n=81), we examined relationships between acuity and both morphological (eye size and body size) and ecological (light level, water turbidity, habitat spatial complexity and diet) variables. Acuity was significantly correlated with eye size (P<0.001); a weaker correlation with body size occurred via a correlation between eye and body size (P<0.001). Acuity decreased as light level decreased and turbidity increased; however, these decreases resulted from fishes in dark or murky environments having smaller eyes and bodies than those in bright or clear environments. We also found significantly lower acuity in horizon-dominated habitats than in featureless or complex habitats. Higher acuity in featureless habitats is likely due to species having absolutely larger eyes and bodies in that environment, though eye size relative to body size is not significantly different from that in complex environments. Controlling for relative eye size, we found that species in complex environments have even higher acuity than predicted. We found no relationship between visual acuity and diet. Our results show that eye size is a primary factor underlying variation in fish acuity. We additionally show that habitat type is an important ecological factor that correlates with acuity in certain species.

Maternal investment and size-specific reproductive output in carcharhinid sharks

Abstract: 1. Life-history theory predicts that organisms will provide an optimal level of parental investment for offspring survival balanced against the effects on their own survival and future reproductive potential. 2. Optimal resource allocation models also predict an increase in reproductive output with age as expected future reproductive effort decreases. To date, maternal investment in sharks has received limited attention. 3. We found that neonatal dusky sharks (Carcharhinus obscurus) are not independent from maternal resource allocation at the point of parturition but instead are provisioned with energy reserves in the form of an enlarged liver that constitutes approximately 20% of total body mass. 4. Analysis of long-term archived data sets showed that a large proportion of this enlarged liver is utilized during the first weeks or months of life suggesting that the reported weight loss of newborn sharks signifies a natural orientation process and is not necessarily related to prey abundance and/or indicative of high mortality rates. 5. Interrogation of near-term pup mass in two carcharhinids, the dusky and spinner shark (Carcharhinus brevipinna), further revealed an increase in reproductive output with maternal size, with evidence for a moderate decline in the largest mothers. 6. For the dusky shark, there was a trade-off between increasing litter size and near-term pup mass in support of optimal offspring size theory. 7. For both the dusky and spinner shark, there was a linear increase in near-term pup mass with month, which may indicate variable parturition strategies and/or that carcharhinids are able to adjust the length of the gestation period. 8. The identification of optimal size-specific reproductive output has direct implications for improving the reproductive potential of exploited shark populations and for structuring future management strategies.

Effect of cadmium exposure on expression of antioxidant gene transcripts in the river pufferfish, Takifugu obscurus (Tetraodontiformes).

Abstract: Cadmium (Cd) is a non-essential toxic heavy metal with the potential to induce oxidative stress Cd toxicity and its capacity for accumulation in aquatic habitats have earned its recognition as a pollutant of immediate and widespread concern To obtain a better understanding of oxidative stress-associated gene expression in different tissues, six antioxidant genes such as catalase (CAT), glutathione reductase (GR), glutathione peroxidase 1a (GPx1a), glutathione peroxidase 1b (GPx1b), Cu/Zn superoxide dismutase (Cu/Zn-SOD), and Mn superoxide dismutase (Mn-SOD) were cloned and fully sequenced in the river pufferfish, Takifugu obscurus On tissue specific mRNA expression, the liver showed the highest expression when compared to other tissues, even though each antioxidant gene showed different modes of expression patterns in the examined tissues Of the various antioxidant genes, GR was the most highly expressed in the liver, followed by CAT, GPx1, and Cu/Zn-SOD For the time-course experiment, all the antioxidant genes were significantly induced over time except for Cu/Zn-SOD in the liver, and there was a 5-fold induction in hepatic GR, CAT, and Mn-SOD mRNA compared to the control These findings indicate that the liver of T obscurus has a robust antioxidant system In addition, these results suggest that Cd exposure modulates the expression of antioxidant genes, and would indicate that the antioxidant genes would be a relevant biomarker of trace metal pollution such as Cd exposure in T obscurus