Does reproductive effort influence the metabolic rate of Tomodon dorsatus snakes?

In Squamate reptiles, vitellogenesis in females is marked by an increase in the number and size of follicles, leading to an increase in aerobic metabolism to support the rising energy demand during reproductive activity. Male gametes are smaller than female gametes, and spermiogenesis requires less energy than vitellogenesis. This investigation compares the relationship between aerobic metabolism and reproductive effort in male and female viviparous Tomodon dorsatus snakes. We evaluated the influence of the males' and females' reproductive stages, along with the masses of follicles and testicles, on their aerobic metabolic rate. Our findings show that females have higher maintenance cost of pregnancy than metabolic costs of vitellogenesis. In males, we found no evidence of the reproductive effort influencing aerobic metabolic rates. In T. dorsatus, females have a long period of development and high fecundity. Therefore, the metabolic costs of vitellogenesis represent a critical component in the reproductive effort. On the other hand, males of T. dorsatus maintain a similar mass of gonads throughout the year with constant energy demand. These results reflect the difference in reproductive efforts between females and males of T. dorsatus.     

Characterization of Key Glycolytic and Oxidative Enzymes in Steinernema carpocapsae

The enzyme activities of isocitrate dehydrogenase (ICDH, NADP-specific), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), phosphoenolpyruvate carboxykinase (PEPCK), phosphofructokinase (PFK), pyruvate kinase (PK), and fructose-l,6-bisphosphatase (FBPase) were studied in the third-stage juveniles of Steinernema carpocapsae. Reaction requirements, pH optima, substrate and cofactor kinetic constants were similar to those reported previously from other parasitic helminths with the exception of LDH, which was unstable and could not be characterized for specific activity and kinetic constants. The respective pH optima were 7.5 for ICDH, 8.8 for MDH, 6.5 for PEPCK, 7.3 for PFK, 7.2 for PK, and 7.5 for FBPase. The specific activities for ICDH, MDH, PEPCK, PFK, PK, and FBPase at pH 7.5 were 4.8, 1,300, 22, 25, 35, and 6.8 (nmoles substrate ∙ min⁻¹ ∙ mg protein⁻¹), respectively. In summary, the infective juveniles of S. carpocapsae display the metabolism typical of a facultative aerobe.     

Upper thermal tolerance plasticity in tropical amphibian species from contrasting habitats: Implications for warming impact prediction

Tropical ectothermic species are currently depicted as more vulnerable to increasing temperatures because of the proximity between their upper thermal limits and environmental temperatures. Yet, the acclimatory capacity of thermal limits has rarely been measured in tropical species, even though they are generally predicted to be smaller than in temperate species. We compared critical thermal maximum (CT_max) and warming tolerance (WT: the difference between CT_max and maximum temperature, T_max), as well as CT_max acclimatory capacity of toad species from the Atlantic forest (AF) and the Brazilian Caatinga (CAA), a semi-arid habitat with high temperatures. Acclimation temperatures represented the mean temperatures of AF and CAA habitats, making estimates of CT_max and WT more ecologically realistic. CAA species mean CT_max was higher compared to AF species in both acclimation treatments. Clutches within species, as well as between AF and CAA species, differed in CT_max plasticity and we discuss the potential biological meaning of these findings. We did not find a trade-off between absolute CT_max and CT_max plasticity, indicating that species can have both high CT_max and high CT_max plasticity. Although CT_max was highly correlated to T_max, CT_max plasticity was not related to T_max or T_max coefficients of variation. CAA species mean WT was lower than for AF species, but still very high for all species, diverging from other studies with tropical species. This might be partially related to over-estimation of vulnerability due to under-appreciation of realistic acclimation treatments in CT_max estimation. Thus, some tropical species might not be as vulnerable to warming as previously predicted if CT_max is considered as a shifting population parameter.     

Novel Functions of CD147 in the Mitochondria Exacerbates Melanoma Metastasis

Melanoma is an aggressive form of skin cancer characterized by rapid invasion and metastasis. CD147 is known to be functioning in cell invasion. In this study, we showed that CD147 was translocated from the cell membrane to the mitochondria in advanced melanoma. Melanoma patients with CD147 localized to the mitochondria confer a worse prognosis. The mitochondrial CD147 levels are correlated with the invasion potential of various melanoma cell lines as well as mitochondrial energy metabolism. Depletion of CD147 decreased the activity of mitochondrial complex V. STRING analysis for protein-protein interaction networks (PPIN) in CD147-depleted melanoma cells showed that mitochondrial proteins HSP60 and ATP5B, a subunit of mitochondrial complex V, were node proteins. HSP60 upregulation was correlated with a worse prognosis of melanoma patients. Co-immunoprecipitation (Co-IP) assay indicates that CD147 interacts with HSP60. These data suggested that mitochondrial CD147 may prompt HSP60 to activate ATP5B, thereby promoting the mitochondrial aerobic oxidation and the invasive abilities of melanoma cells. Correlation analysis of the data acquired from patients was helpful to draw a 5-year survival curve for patients who screened positive and negative for mitochondrial CD147. This study unravels the function of CD147 in tumor invasion and highlights it as a potential tumor therapeutic target.     

NEAT1 is essential for metabolic changes that promote breast cancer growth and metastasis

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Aerobic glycolysis: a study of human articular cartilage

Cartilage generally is one of those tissues that exhibit aerobic glycolysis. In a previous study on rat epiphyseal cartilage it had been suggested that this phenomenon is related to potentially excessive production of pyruvate and acetyl coenzyme A, the latter derived from fatty acid oxidation and inhibiting pyruvate dehydrogenase activity. The present study has shown that, in human articular cartilage, the contribution from fatty acid oxidation is too small to account for this phenomenon although the total potential production of pyruvate could still be in excess of the requirements for acetyl coenzyme A for the Krebs' cycle. Of greater relevance may be the apparent correlations that have been found between the activities of lactate and glyceraldehyde 3-phosphate dehydrogenases (r = 0 X 82: 0.01 greater than p greater than 0.001) and between those of lactate and glucose 6-phosphate dehydrogenases (r = 0.92; p less than 0.001).     

好氧氨氧化过程中的关键酶及N2O排放研究进展

氧化亚氮(nitrous oxide, N₂O)排放量的持续增加对全球生态平衡造成了严重的威胁。微生物N₂O排放占主要来源。其中,好氧氨氧化过程是氨在有氧的条件下氧化为亚硝酸盐,其直接或间接地影响着全球产生N₂O与释放量。氨氧化古菌(ammonia-oxidizing archaea, AOA)、氨氧化细菌(ammonia-oxidizing bacteria, AOB)、全程氨氧化菌(complete ammonia oxidization, Comammox)和异养氨氧化菌(heterotrophic ammonium oxidizing bacteria, HAOB)是氨氧化过程中主要的参与者,明确这四类微生物N₂O产生的机制对缓解全球N₂O排放是必要的。本文综述了AOA、AOB、Comammox和HAOB在好氧氨氧化过程中驱动的N₂O产生途径,并结合酶学分析了一些关键酶在N₂O产生途径中的作用。本文旨在为调控生物N₂O排放提供理论基础。