Science education reforms consistently maintain the goal that students develop an understanding of the nature of science, including both the nature of scientific knowledge and methods for making it. ...This paper articulates a framework for scaffolding epistemic aspects of inquiry that can help students understand inquiry processes in relation to the kinds of knowledge such processes can produce. This framework underlies the design of a technology-supported inquiry curriculum for evolution and natural selection that focuses students on constructing and evaluating scientific explanations for natural phenomena. The design has been refined through cycles of implementation, analysis, and revision that have documented the epistemic practices students engage in during inquiry, indicate ways in which designed tools support students' work, and suggest necessary additional social scaffolds. These findings suggest that epistemic tools can play a unique role in supporting students' inquiry, and a fruitful means for studying students' scientific epistemologies.
Multiethnicity in Teopancazco, Teotihuacan, is supported by foreign individuals found in the neighborhood center as well as by the diversity observed in funerary rituals at the site. Studies of both ...stable and strontium isotopes as well as paleodietary analysis, suggest that the population of Teopancazco was composed by three population groups: people from Teotihuacan, people from nearby sites (Tlaxcala-Hidalgo-Puebla), and people from afar, including the coastal plains. In an attempt to understand the genetic dynamics in Teopancazco we conducted an ancient DNA (aDNA) analysis based on mtDNA. Our results show that the level of genetic diversity is consistent with the multiethnicity phenomenon at the neighborhood center. Levels of genetic diversity at different time periods of Teopancazco's history show that multiethnicity was evident since the beginning and lasted until the collapse of the neighborhood center. However, a PCA and a Neighbor-Joining tree suggested the presence of a genetically differentiated group (buried at the Transitional phase) compared to the population from the initial phase (Tlamimilolpa) as well as the population from the final phase (Xolalpan) of the history of Teopancazco. Genetic studies showed no differences in genetic diversity between males and females in the adult population of Teopancazco, this data along with ample archaeological evidence, suggest a neolocal post-marital pattern of residence in Teopancazco. Nevertheless, genetic analyses on the infant population showed that the males are significantly more heterogeneous than the females suggesting a possible differential role in cultural practices by sex in the infant sector. Regarding interpopulation analysis, we found similar indices of genetic diversity between Teopancazco and heterogeneous native groups, which support the multiethnic character of Teopancazco. Finally, our data showed a close genetic relationship between Teopancazco and populations from the "Teotihuacan corridor" and from Oaxaca and the Maya region, in agreement with previous archaeological evidence.
Glucagon-like peptide 1 (GLP-1), a peptide secreted from the intestine in response to nutrient ingestion, is perhaps best known for its effect on glucose-stimulated insulin secretion. GLP-1 is also ...secreted from neurons in the caudal brainstem, and it is well-established that, in rodents, central administration of GLP-1 potently reduces food intake. Over the past decade, GLP-1 has emerged not only as an essential component of the system that regulates blood glucose levels but also as a viable therapeutic target for the treatment of type 2 diabetes mellitus. However, although GLP-1 receptor agonists are known to produce modest but statistically significant weight loss in patients with diabetes mellitus, our knowledge of how endogenous GLP-1 regulates food intake and body weight remains limited. The purpose of this Review is to discuss the evolution of our understanding of how endogenous GLP-1 modulates energy balance. Specifically, we consider contributions of both central and peripheral GLP-1 and propose an integrated model of short-term and long-term control of energy balance. Finally, we discuss this model with respect to current GLP-1-based therapies and suggest ongoing research in order to maximize the effectiveness of GLP-1-based treatment of obesity.
Cancer cells require a robust supply of reduced nitrogen to produce nucleotides, non-essential amino acids and a high cellular redox activity. Glutamine provides a major substrate for respiration as ...well as nitrogen for the production of proteins, hexosamines, and macromolecules. Therefore, glutamine is one of key molecules in cancer metabolism during cell proliferation. The notion of targeting glutamine metabolism in cancer, originally rationalized by the number of pathways fed by this nutrient, has been reinforced by more recent studies demonstrating that its metabolism is regulated by oncogenes. Glutamine can exert its effects by modulating redox homeostasis, bioenergetics, nitrogen balance or other functions, including by being a precursor of glutathione, the major nonenzymatic cellular antioxidant. Glutaminase (GA) is the first enzyme that converts glutamine to glutamate, which is in turn converted to alpha-ketoglutarate for further metabolism in the tricarboxylic acid cycle. Different GA isoforms in mammals are encoded by two genes, Gls and Gls2. As each enzymatic form of GA has distinct kinetic and molecular characteristics, it has been speculated that the differential regulation of GA isoforms may reflect distinct functions or requirements in different tissues or cell states. GA encoded by Gls gene (GLS) has been demonstrated to be regulated by oncogenes and to support tumor cell growth. GA encoded by Gls2 gene (GLS2) reduces cellular sensitivity to reactive oxygen species associated apoptosis possibly through glutathione-dependent antioxidant defense, and therefore to behave more like a tumor suppressor. Thus, modulation of GA function may be a new therapeutic target for cancer treatment.
Neonatal encephalopathy (NE) describes the clinical syndrome of a newborn with abnormal brain function that may result from a variety of etiologies. HIE should be distinguished from neonatal ...encephalopathy due to other causes using data gathered from the history, physical and neurological exam, and further investigations. Identifying the underlying cause of encephalopathy has important treatment implications. This review outlines conditions that cause NE and may be mistaken for HIE, along with their distinguishing clinical features, pathophysiology, investigations, and treatments. NE due to brain malformations, vascular causes, neuromuscular causes, genetic conditions, neurogenetic disorders and inborn errors of metabolism, central nervous system (CNS) and systemic infections, and toxic/metabolic disturbances are discussed.
To understand hindbrain pathways involved in the control of food intake, we examined roles for calcitonin receptor (CALCR)-containing neurons in the NTS. Ablation of NTS Calcr abrogated the long-term ...suppression of food intake, but not aversive responses, by CALCR agonists. Similarly, activating CalcrNTS neurons decreased food intake and body weight but (unlike neighboring CckNTS cells) failed to promote aversion, revealing that CalcrNTS neurons mediate a non-aversive suppression of food intake. While both CalcrNTS and CckNTS neurons decreased feeding via projections to the PBN, CckNTS cells activated aversive CGRPPBN cells while CalcrNTS cells activated distinct non-CGRP PBN cells. Hence, CalcrNTS cells suppress feeding via non-aversive, non-CGRP PBN targets. Additionally, silencing CalcrNTS cells blunted food intake suppression by gut peptides and nutrients, increasing food intake and promoting obesity. Hence, CalcrNTS neurons define a hindbrain system that participates in physiological energy balance and suppresses food intake without activating aversive systems.
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•NTS Calcr mediates food intake suppression but not aversive responses to sCT•Activating NTS Calcr neurons non-aversively suppresses feeding•These neurons act via non-CGRP PBN neurons•These neurons control long-term energy balance, not just short-term feeding
While the hindbrain is often postulated to control only short-term parameters of feeding via circuits that mediate aversive responses when activated strongly, Cheng et al. have identified a hindbrain system that participates in the physiological control of energy balance and suppresses food intake without activating aversive systems or symptoms.
The competitive, profitable, and safe operation of chemical plants depends on tight and effective coordination among the different decision making levels of the enterprise, including planning, ...scheduling, and control. The optimal integration of these functions has become critical given the disruptive effects of the recent COVID‐19 pandemic on the supply chains and the current trends in climate change. However, integrating multiple decision making levels creates modelling and computational challenges. In this study, we review the progress made in the integration of two and three decisions levels using mathematical programming and control theory tools. We highlight the model reduction and decomposition techniques that have been applied, as well as the main issues that remain unsolved. Perspectives on emergent areas of application and novel computing solutions are also discussed.
In exchange for extrafloral nectar, ants deter herbivores from the plants decreasing the herbivore damage, and increasing plant performance in terms of growth and survival. Plants of different sexes ...may exhibit differences in the investment of resources for defence, thereby differentially decreasing the amount of energy available to other physiological processes. In this context, little is known about sex‐related differences in the outcome of ant–plant interactions in plants bearing extrafloral nectaries (EFNs).
In the present study, we conducted ant‐exclusion experiments in the field to test for sex‐related differences in the outcome of ant–plant interactions in vegetative and reproductive buds of Opuntia robusta in individuals of different sexes in two populations: trioecious and dioecious. We applied tanglefoot to some plant and others were allowed ant access, and measured herbivory, relative growth rates and survival probabilities of buds during the growing season when EFNs are active. We counted the number of ants foraging in EFNs of flowers and cladodes of different sexes. We hypothesized that differences in resource investment to defence between sexes change the outcome of ant–plant interactions in terms of the number of ants foraging on EFNs, herbivory, growth, and survival probabilities.
Our results suggest sex‐specific strategies in the investment of resources for defence mediated by EFNs in O. robusta, wherein males, females and hermaphrodites from both populations respond differentially to ant presence and herbivores. These sex‐related differences affected the outcome of the ant–plant interactions, influencing changes in number of ants foraging on EFNs, and the resulting herbivory, growth and survival of flowers and cladodes among the different sexes and among populations. Our results suggest that the maintenance of EFNs in O. robusta is costly, reflecting some trade‐offs between growth/survival and defence. Buds visited by ants tended to grow slowly and survive worse in the trioecious population; in the dioecious population they grew slower but survived better. Overall, a greater number of ants visiting EFNs was related to lower herbivore damage, greater growth and survival of flowers and cladodes. Our study underscores the importance of considering plant sex in the outcome of ant–plant interactions.
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Abstract
Dietary changes are the major variation cause in the composition of the gut microbiota. The short lactation phase in phocids provides an exceptional opportunity to explore the microbiota's ...response to a quick transition from a milk-based to a solid diet. We investigated the effects of age and sex on the gut microbiota of harbor seals in Mexico using rectal and fecal samples from pups and adults. 16S gene sequencing revealed age explains most of the observed variations in microbial composition. Individuals with frequent contact (pups—female adults) have major microbial similarities than those with little or no contact (pups—male adults). Overall, adults and females (regardless of sex and age, respectively) have a greater microbial richness; as seals grow, the core microbiome shrinks, and microbial diversity increases. We found pathways related to milk and chitin digestion in pups' microbiomes, indicating pups were transitioning to a solid diet. An enrichment of routes related to dramatic weight loss and body mass indicated higher metabolic stress in pups in late breeding season, when they are weaned and start intermittent fasting. Our findings highlight the host-microbiome interaction in harbor seals during late breeding season in response to food shifts and metabolic stress.
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