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Exercise stimulates glucose uptake and increases insulin sensitivity acutely. Temporally optimizing exercise timing may minimize the nocturnal rise in glucose levels. This study examined the effect of exercise timing on evening and overnight glucose concentrations in individuals who were non-obese with normal fasting glucose levels (Non-Ob; n = 18) and individuals with obesity (OB) with impaired fasting glucose levels (OB+IFG) and without (n = 16 and n = 18, respectively). Subjects were studied on three occasions (no exercise (NOEX)), morning exercise (AMEX; 0700 h) and evening exercise (PMEX; 2000 h). The evening meal was provided (1800 h) and blood samples were taken from 1740 to 0700 h and morning endogenous glucose production (EGP) was measured. Glucose and insulin concentrations increased with the dinner meal with peak concentrations being higher in OB+IFG than in OB and Non-Ob (P = 0.04). In OB+IFG, evening glucose concentrations rose above baseline levels at about 2300 h, with the glucose concentrations staying somewhat lower with AMEX and PMEX until ∼0500 h than with NOEX. In OB+IFG, insulin concentrations decreased following the dinner meal and waned throughout the night, despite the rising glucose concentrations. In the OB and Non-Ob individuals following the dinner meal, no increase in glucose concentrations occurred in the evening period and insulin levels mirrored this. No difference was observed in the morning fasting glucose levels between study days or between groups. Regardless of time of day, exercise delays the evening rise in glucose concentrations in adults with OB+IFG but does not lower morning fasting glucose levels or improve the synchrony between glucose and insulin concentrations. KEY POINTS: Insulin resistance and type 2 diabetes have been linked to disturbances of the core clock, and glucose tolerance demonstrates a diurnal rhythm in healthy humans with better glucose tolerance in the morning than in the afternoon and evening. Skeletal muscle is a primary site for insulin resistance in people with impaired glucose tolerance. In individuals with obesity and impaired fasting glucose levels (OB+IFG), following a dinner meal, glucose concentrations started to rise and continues throughout the night, resulting in elevated glucose levels, while concomitantly, insulin levels are waning. Exercise, regardless of the time of day, suppressed the rise in glucose levels in OB+IFG for many hours during the night but did not lower morning fasting glucose levels. Morning exercise was not quite as effective as evening exercise., (© 2023 The Authors. The Journal of Physiology © 2023 The Physiological Society.)

Sleep restriction (SR) (<6 h) and physical activity (PA) are risk factors for obesity, but little work has examined the inter-related influences of both risk factors. In a free-living environment, 13 overweight/obese adults were sleep restricted for five nights to 6 h time-in-bed each night, with and without regular exercise (45 min/65% VO 2 max; counterbalanced design). Two days of recovery sleep followed SR. Subjects were measured during a mixed meal tolerance test (MMT), resting metabolic rate, cognitive testing and fat biopsy (n=8). SR increased peak glucose response (+7.3 mg/dl, p = .04), elevated fasting non-esterified fatty acid (NEFA) concentrations (+0.1 mmol/L, p = .001) and enhanced fat oxidation (p < .001) without modifying step counts or PA intensity. Inclusion of daily exercise increased step count (+4,700 steps/day, p < .001) and decreased the insulin response to a meal (p = .01) but did not prevent the increased peak glucose response or elevated NEFA levels. The weekend recovery period improved fasting glucose (p = .02), insulin (p = .02), NEFA concentrations (p = .001) and HOMA-IR (p < .01) despite reduced steps (p < .01) and increased sedentary time (p < .01). Abdominal adipose tissue (AT) samples, obtained after baseline, SR and exercise, did not differ in lipolytic capacity following SR. Fatty acid synthase protein content tended to increase following SR (p = .07), but not following exercise. In a free-living setting, SR adversely affected circulating NEFAs, fuel oxidation and peak glucose response but did not directly affect glucose tolerance or AT lipolysis. SR-associated metabolic impairments were not mitigated by exercise, yet recovery sleep completely rescued its adverse effects on glucose metabolism., (© 2021 European Sleep Research Society.)

During exercise, there is coordination between various hormonal systems to ensure glucoregulation. This study examined if hypoglycemia occurs during moderate-intensity exercise in non-obese and obese individuals with and without type 2 diabetes (T2D). Eighteen non-obese, 18 obese, and 10 obese with T2D completed 2 study days that included a meal at 1,800 h followed by rest (NOEX) or exercise (PMEX; 45 min/55% of VO 2 max 2 h post meal). Glucose, insulin, and glucagon concentrations were measured throughout this 5.5 h period. Subjects with T2D had elevated glucose responses to the meal on both study days, compared to non-obese and obese subjects ( P < 0.05). During evening exercise (PMEX), subjects with T2D had a greater drop in glucose concentration (-98.4 ± 13.3 mg/dL) compared to obese (-44.8 ± 7.1 mg/dL) and non-obese (-39.3 ± 6.1 mg/dL; P < 0.01) subjects. Glucose levels decreased more so in females than males in both conditions ( P < 0.01). Nadir glucose levels <70 mg/dL were observed in 33 subjects during NOEX and 39 subjects during PMEX. Obese males had a larger exercise-induced insulin drop than obese females ( P = 0.01). During PMEX, peak glucagon concentrations were elevated compared to NOEX ( P < 0.001). Male participants with T2D had an increased glucagon response during NOEX and PMEX compared to females ( P < 0.01). In conclusion, in individuals with varying glucose tolerance, there is a dramatic drop in glucose levels during moderate-intensity exercise, despite appropriate insulin concentrations prior to exercise, and glucagon levels rising during exercise. Moderate-intensity exercise can result in low glucose concentrations (<60 mg/dL), and yet many of these individuals will be asymptomatic., (Copyright © 2020 Porter, Pettit-Mee, Ready, Liu, Lastra, Chockalingam, Winn, Clart and Kanaley.)

Objective: The aim of this study was to examine the effects of sex and menopausal status on depot-specific estrogen signaling in white adipose tissue (AT) in age-matched men and women with morbid obesity., Methods: A total of 28 premenopausal women, 16 postmenopausal women, and 27 age-matched men undergoing bariatric surgery were compared for omental (OM) AT (OMAT) and abdominal subcutaneous (SQ) AT (SQAT) genes and proteins., Results: With the exception of fasting nonesterified fatty acids being higher in women (P < 0.01), no differences were found in other indicators of glucose and lipid metabolism. In OMAT, estrogen receptor (ER) beta (ERβ) levels were higher in older women than in younger women and older men (sex-age interaction, P < 0.01), and aromatase expression was higher in older men than in older women (P < 0.05). In SQAT, women had lower expression of ERβ than men (P < 0.05). Protein content of ER alpha and ERβ was highly correlated with the mitochondrial protein uncoupling protein 1 across sexes and ages (P < 0.001). Age increased SQ inflammatory gene expression in both sexes., Conclusions: In morbid obesity, sex and age affect AT ERs, lipid metabolism, mitochondrial uncoupling protein 1, and inflammatory expression in an AT depot-dependent manner. The SQAT immunometabolic profile is heavily influenced by age and menopause status, more so than OMAT., (© 2020 The Obesity Society.)

This article investigates National Defense Education Act and National Defense Education Act-related calls in the late 1950s for the training of guidance counselors, an emergent profession that was to play an instrumental role in both the measuring and placement of students in schools by "intelligence" or academic "ability". In analyzing this mid-century push for more guidance counseling in schools, this article will first explore a foundational argument for the fairness of intelligence testing made by Educational Testing Service psychometrician William Turnbull in 1951, and then later taken up and employed by other National Defense Education Act-era advocates of testing and grouping. Secondly, this analysis will proceed to National Defense Education Act expert testimony, examining here assertions of the necessity of guidance counseling in schools, and an emergent and shared vision articulating the role guidance counseling was supposed to play in school life. A pattern or structure to this vision emerges here. According to its advocates, guidance counseling would not only inform the self-understanding of the measured individual, but it would also work to condition the ideology of individual intelligence across numerous layers of social life around the student: through peer group, through teachers and school administrators, and finally through home, family, and the wider community.

Coral reefs worldwide are threatened by thermal stress caused by climate change. Especially devastating periods of coral loss frequently occur during El Niño-Southern Oscillation (ENSO) events originating in the Eastern Tropical Pacific (ETP). El Niño-induced thermal stress is considered the primary threat to ETP coral reefs. An increase in the frequency and intensity of ENSO events predicted in the coming decades threatens a pan-tropical collapse of coral reefs. During the 1982-1983 El Niño, most reefs in the Galapagos Islands collapsed, and many more in the region were decimated by massive coral bleaching and mortality. However, after repeated thermal stress disturbances, such as those caused by the 1997-1998 El Niño, ETP corals reefs have demonstrated regional persistence and resiliency. Using a 44 year dataset (1970-2014) of live coral cover from the ETP, we assess whether ETP reefs exhibit the same decline as seen globally for other reefs. Also, we compare the ETP live coral cover rate of change with data from the maximum Degree Heating Weeks experienced by these reefs to assess the role of thermal stress on coral reef survival. We find that during the period 1970-2014, ETP coral cover exhibited temporary reductions following major ENSO events, but no overall decline. Further, we find that ETP reef recovery patterns allow coral to persist under these El Niño-stressed conditions, often recovering from these events in 10-15 years. Accumulative heat stress explains 31% of the overall annual rate of change of living coral cover in the ETP. This suggests that ETP coral reefs have adapted to thermal extremes to date, and may have the ability to adapt to near-term future climate-change thermal anomalies. These findings for ETP reef resilience may provide general insights for the future of coral reef survival and recovery elsewhere under intensifying El Niño scenarios., (© 2020 John Wiley & Sons Ltd.)

Exercise enhances insulin sensitivity; it also improves adipocyte metabolism and reduces adipose tissue inflammation through poorly defined mechanisms. Fibroblast growth factor 21 (FGF21) is a pleiotropic hormone-like protein whose insulin-sensitizing properties are predominantly mediated via receptor signaling in adipose tissue (AT). Recently, FGF21 has also been demonstrated to have anti-inflammatory properties. Meanwhile, an association between exercise and increased circulating FGF21 levels has been reported in some, but not all studies. Thus, the role that FGF21 plays in mediating the positive metabolic effects of exercise in AT are unclear. In this study, FGF21-knockout (KO) mice were used to directly assess the role of FGF21 in mediating the metabolic and anti-inflammatory effects of exercise on white AT (WAT) and brown AT (BAT). Male FGF21KO and wild-type mice were provided running wheels or remained sedentary for 8 weeks ( n  = 9-15/group) and compared for adiposity, insulin sensitivity (i.e., HOMA-IR, Adipo-IR) and AT inflammation and metabolic function (e.g., mitochondrial enzyme activity, subunit content). Adiposity and Adipo-IR were increased in FGF21KO mice and decreased by EX. The BAT of FGF21KO animals had reduced mitochondrial content and decreased relative mass, both normalized by EX. WAT and BAT inflammation was elevated in FGF21KO mice, reduced in both genotypes by EX. EX increased WAT Pgc1alpha gene expression, citrate synthase activity, COX I content and total AMPK content in WT but not FGF21KO mice. Collectively, these findings reveal a previously unappreciated anti-inflammatory role for FGF21 in WAT and BAT, but do not support that FGF21 is necessary for EX-mediated anti-inflammatory effects., (© 2017 Society for Endocrinology.)

Carbohydrate ingestion and level of concentric versus eccentric muscle activity may alter exercise-induced health benefits for individuals who have high waist circumference as a metabolic risk factor. The purpose of this study was to determine whether metabolic and inflammation responses to an exercise recovery meal differ between women with lower (Lo-WC, <80 cm) compared with higher (Hi-WC) waist circumference when the exercise is primarily concentric (uphill walking; UPHILL) versus primarily eccentric (downhill walking; DOWNHILL). Recreationally active women (age, 18-39 years; body mass index, 19-35.4 m·kg -2 ; Lo-WC, n = 13; Hi-WC, n = 10) completed UPHILL, DOWNHILL, and resting (CONTROL) conditions followed 30 min later by a mixed meal tolerance test (MMTT) with carbohydrates to protein ratio of 4:1, and blood glucose, insulin, and inflammation markers were compared across conditions. Compared with Lo-WC, the Hi-WC group had higher (p < 0.05) (i) insulin during the MMTT in CONTROL (mean ± SE; 48.5 ± 8.2 vs 22.9 ± 2.8 pmol·L -1 ), (ii) baseline (0.7 ± 0.4 vs 2.0 ± 1.7 pg·mL -1 ) interleukin-6 (IL-6), and (iii) IL-6 responses 8 h after UPHILL and CONTROL. Both groups had (i) increases in IL-6 at 0 h after UPHILL and at 8 h after DOWNHILL, and (ii) lower glycemic responses in UPHILL. Women with Hi-WC had higher IL-6 at rest and delayed increases in IL-6 after a high-carbohydrate meal in all conditions. This is consistent with an inflammation response to the meal and or uphill walking exercise. However, both concentrically and eccentrically biased exercises offered benefits to insulin responses to a high carbohydrate meal for Hi-WC.

We propose 'the moving target hypothesis' to describe the aetiology of a contemporary coral disease that differs from that of its historical disease state. Hitting the target with coral disease aetiology is a complex pursuit that requires understanding of host and environment, and may lack a single pathogen solution. White pox disease (WPX) affects the Caribbean coral Acropora palmata. Acroporid serratiosis is a form of WPX for which the bacterial pathogen (Serratia marcescens) has been established. We used long-term (1994-2014) photographic monitoring to evaluate historical and contemporary epizootiology and aetiology of WPX affecting A. palmata at eight reefs in the Florida Keys. Ranges of WPX prevalence over time (0-71.4%) were comparable for the duration of the 20-year study. Whole colony mortality and disease severity were high in historical (1994-2004), and low in contemporary (2008-2014), outbreaks of WPX. Acroporid serratiosis was diagnosed for some historical (1999, 2003) and contemporary (2012, 2013) outbreaks, but this form of WPX was not confirmed for all WPX cases. Our results serve as a context for considering aetiology as a moving target for WPX and other coral diseases for which pathogens are established and/or candidate pathogens are identified. Coral aetiology investigations completed to date suggest that changes in pathogen, host and/or environment alter the disease state and complicate diagnosis., (© 2016 The Author(s).)

Coral surface mucus layer (SML) microbiota are critical components of the coral holobiont and play important roles in nutrient cycling and defense against pathogens. We sequenced 16S rRNA amplicons to examine the structure of the SML microbiome within and between colonies of the threatened Caribbean reef-building coral Acropora palmata in the Florida Keys. Samples were taken from three spatially distinct colony regions--uppermost (high irradiance), underside (low irradiance), and the colony base--representing microhabitats that vary in irradiance and water flow. Phylogenetic diversity (PD) values of coral SML bacteria communities were greater than surrounding seawater and lower than adjacent sediment. Bacterial diversity and community composition was consistent among the three microhabitats. Cyanobacteria, Bacteroidetes, Alphaproteobacteria, and Proteobacteria, respectively were the most abundant phyla represented in the samples. This is the first time spatial variability of the surface mucus layer of A. palmata has been studied. Homogeneity in the microbiome of A. palmata contrasts with SML heterogeneity found in other Caribbean corals. These findings suggest that, during non-stressful conditions, host regulation of SML microbiota may override diverse physiochemical influences induced by the topographical complexity of A. palmata. Documenting the spatial distribution of SML microbes is essential to understanding the functional roles these microorganisms play in coral health and adaptability to environmental perturbations.

White pox disease (WPD) affects the threatened elkhorn coral, Acropora palmata. Owing in part to the lack of a rapid and simple diagnostic test, there have been few systematic assessments of the prevalence of acroporid serratiosis (caused specifically by Serratia marcescens) versus general WPD signs. Six reefs in the Florida Keys were surveyed between 2011 and 2013 to determine the disease status of A. palmata and the prevalence of S. marcescens. WPD was noted at four of the six reefs, with WPD lesions found on 8 to 40% of the colonies surveyed. S. marcescens was detected in 26.9% (7/26) of the WPD lesions and in mucus from apparently healthy colonies both during and outside of disease events (9%; 18/201). S. marcescens was detected with greater frequency in A. palmata than in the overlying water column, regardless of disease status (P = 0.0177). S. marcescens could not be cultured from A. palmata but was isolated from healthy colonies of other coral species and was identified as pathogenic pulsed-field gel electrophoresis type PDR60. WPD lesions were frequently observed on the reef, but unlike in prior outbreaks, no whole-colony death was observed. Pathogenic S. marcescens was circulating on the reef but did not appear to be the primary pathogen in these recent WPD episodes, suggesting that other pathogens or stressors may contribute to signs of WPD. Results highlight the critical importance of diagnostics in coral disease investigations, especially given that field manifestation of disease may be similar, regardless of the etiological agent., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

The fluorescent protein (FP) gene family is a highly diverse group of proteins whose expression govern color diversity in corals. Here, we examine the genetic diversity of FPs and the extent to which it can be used to assess phylogenetic relationships within the coral genus Agaricia. Tissue samples were collected throughout the Florida Keys from a wide range of phenotypes within the genus Agaricia (A. agaricites [n = 7], A. fragilis [n = 13], and A. lamarcki [n = 2]), as well as the confamilial species Helioseris cucullata (n = 3). Primers were developed from published cDNA sequences to amplify a region of coding and noncoding sequences of FPs. Cloning reactions were performed to capture the multiple copies of FPs and allele diversity. In the resulting 116 cloned sequences, we identified a 179-bp coding region for phylogenetic analysis. Three distinct clades were found in all 3 species of Agaricia, potentially representing 3 copies of the FP gene. Of the 3 gene copies, 2 contain distinct subclades that display reciprocal monophyly between A. agaricites and A. fragilis, whereas A. lamarcki is polyphyletic. Further resolution of the species phylogeny is necessary to fully understand how genetic diversity within this gene family is distributed among taxa and habitats.

Coral reefs are in severe decline. Infections by the human pathogen Serratia marcescens have contributed to precipitous losses in the common Caribbean elkhorn coral, Acropora palmata, culminating in its listing under the United States Endangered Species Act. During a 2003 outbreak of this coral disease, called acroporid serratiosis (APS), a unique strain of the pathogen, Serratia marcescens strain PDR60, was identified from diseased A. palmata, human wastewater, the non-host coral Siderastrea siderea and the corallivorous snail Coralliophila abbreviata. In order to examine humans as a source and other marine invertebrates as vectors and/or reservoirs of the APS pathogen, challenge experiments were conducted with A. palmata maintained in closed aquaria to determine infectivity of strain PDR60 from reef and wastewater sources. Strain PDR60 from wastewater and diseased A. palmata caused disease signs in elkhorn coral in as little as four and five days, respectively, demonstrating that wastewater is a definitive source of APS and identifying human strain PDR60 as a coral pathogen through fulfillment of Koch's postulates. A. palmata inoculated with strain PDR60 from C. abbreviata showed limited virulence, with one of three inoculated fragments developing APS signs within 13 days. Strain PDR60 from non-host coral S. siderea showed a delayed pathogenic effect, with disease signs developing within an average of 20 days. These results suggest that C. abbreviata and non-host corals may function as reservoirs or vectors of the APS pathogen. Our results provide the first example of a marine "reverse zoonosis" involving the transmission of a human pathogen (S. marcescens) to a marine invertebrate (A. palmata). These findings underscore the interaction between public health practices and environmental health indices such as coral reef survival.

Caribbean elkhorn coral, Acropora palmata, has been decimated in recent years, resulting in the listing of this species as threatened under the United States Endangered Species Act. A major contributing factor in the decline of this iconic species is white pox disease. In 2002, we identified the faecal enterobacterium, Serratia marcescens, as an etiological agent for white pox. During outbreaks in 2003 a unique strain of S. marcescens was identified in both human sewage and white pox lesions. This strain (PDR60) was also identified from corallivorious snails (Coralliophila abbreviata), reef water, and two non-acroporid coral species, Siderastrea siderea and Solenastrea bournoni. Identification of PDR60 in sewage, diseased Acropora palmata and other reef invertebrates within a discrete time frame suggests a causal link between white pox and sewage contamination on reefs and supports the conclusion that humans are a likely source of this disease.

PSAPP mice expressing the 'Swedish' amyloid precursor protein and the M146L presenilin 1 mutations are a well-characterized model for spontaneous amyloid beta plaque formation. Centella asiatica has a long history of use in India as a memory enhancing drug in Ayurvedic literature. The study investigated whether Centella asiatica extract (CaE) can alter the amyloid pathology in PSAPP mice by administering CaE (2.5 or 5.0 g/kg/day) starting at 2 months of age prior to the onset of detectable amyloid deposition and continued for either 2 months or 8 months. A significant decrease in amyloid beta 1-40 and 1-42 was detectable by ELISA following an 8 month treatment with 2.5 mg/kg of CaE. A reduction in Congo Red stained fibrillar amyloid plaques was detected with the 5.0 mg/kg CaE dose and long-term treatment regimen. It was also confirmed that CaE functions as an antioxidant in vitro, scavenging free radicals, reducing lipid peroxidation and protecting against DNA damage. The data indicate that CaE can impact the amyloid cascade altering amyloid beta pathology in the brains of PSAPP mice and modulating components of the oxidative stress response that has been implicated in the neurodegenerative changes that occur with Alzheimer's disease., (Copyright 2008 John Wiley & Sons, Ltd.)

Populations of the shallow-water Caribbean elkhorn coral, Acropora palmata, are being decimated by white pox disease, with losses of living cover in the Florida Keys typically in excess of 70%. The rate of tissue loss is rapid, averaging 2.5 cm2 x day(-1), and is greatest during periods of seasonally elevated temperature. In Florida, the spread of white pox fits the contagion model, with nearest neighbors most susceptible to infection. In this report, we identify a common fecal enterobacterium, Serratia marcescens, as the causal agent of white pox. This is the first time, to our knowledge, that a bacterial species associated with the human gut has been shown to be a marine invertebrate pathogen.

This paper examines the implications for river flows of a number of water practices and potential management options in the alluvial plains of the Upper Condamine River. It is an intensively cultivated area where irrigation is limited by the availability of water resources. The practice of capturing overland flows was investigated by the development of a model that simulates the performance of clusters of offstream storages up to sub-catchment scale. Management options examined included improvement to on-farm water use efficiency, the suppression of evaporation from open water storages, increasing the depth of those storages, decreasing their number, and improved tailwater return from irrigated land. Impacts of management options were analysed using a catchment scale water allocation model.

Mass mortalities due to disease outbreaks have recently affected major taxa in the oceans. For closely monitored groups like corals and marine mammals, reports of the frequency of epidemics and the number of new diseases have increased recently. A dramatic global increase in the severity of coral bleaching in 1997-98 is coincident with high El Niño temperatures. Such climate-mediated, physiological stresses may compromise host resistance and increase frequency of opportunistic diseases. Where documented, new diseases typically have emerged through host or range shifts of known pathogens. Both climate and human activities may have also accelerated global transport of species, bringing together pathogens and previously unexposed host populations.

Rabbit IgG prepared against malic enzyme inhibits pigeon liver fatty acid synthetase activity. By screening a number of polyclonal antibodies raised to several dehydrogenases, we have discovered that there is a direct relationship between this cross-reactivity and the existence of a common structural domain whose function is the binding of NADP+/NADPH. The presence of NADP+/NADPH in small concentrations protects against this immunoinhibition, thereby indicating a competitive binding of nucleotide and site-specific antibody at the antigenic domain. These data provide further support for the existence of an antigenic domain in the NADPH binding region of dehydrogenases which is responsible for the production of NADPH site-specific antibodies in polyclonal antisera.

The partially purified phytoene synthetase enzyme complex obtained from tomato fruit plastids dissociates into two or more subunit species on chromatography in low ionic strength buffer on DEAE-cellulose. One of these subunits prelycopersene pyrophosphate synthetase, has a molecular weight of approximately 40,000, whereas the phytoene synthetase complex has a molecular weight of 200,000. The prelycopersene pyrophosphate synthetase catalyzes the conversion of isopentenyl pyrophosphate to geranylgeranyl and prelycopersene pyrophosphates. The identities of these substances were established by thin layer chromatography in several solvent systems. The formation of both geranylgeranyl and prelycopersene pyrophosphates by this enzyme supports earlier results with cruder enzyme systems which suggested that these compounds are intermediates in the synthesis of phytoene.

Immunotitrations of rat liver hydroxymethylglutaryl-CoA (HOMeGlt-CoA) reductase activity were performed before and after short-term changes in the nutritional or hormonal state of the animals. Changes in enzyme activity (increase or decrease) within 1 h following cholesterol feeding or glucagon or mevalonolactone administration to normal rats, or insulin administration to diabetic rats were accompanied by no change in the specific activity of the enzyme, as determined from the quantity of enzyme activity inactivated by a fixed quantity of antibody. These results support the conclusion that the loss in enzyme activity was due to conversion of the enzyme to immuno-unreactive products. In agreement with this conclusion the enzyme activity lost after these short-term physiological changes was not restorable by phosphoprotein phosphatase action. On the other hand, incubation of rat liver microsomes with ATP and Mg2+ decreased the specific activity of HOMeGlt-CoA reductase about tenfold, as determined by immunotitration. The low specific activity produced under these conditions was increased by phosphatase action to nearly the original level. The above evidence suggests that the changes in HOMeGlt-CoA reductase activity that resulted from short-term physiological changes in hormonal or nutritional states of an animal were brought about by a change in the quantity of enzyme, and not by reversible phosphorylation of pre-existing enzyme.

The mechanism of action of yeast beta-hydroxy-beta-methylglutaryl-coenzyme A reductase has been investigated through kinetic studies on the oxidation of mevaldate by nicotinamide adeninine dinucleotide phosphate (NADP) in the presence of coenzyme A (CoA) and on the reduction of mevaldate by reduced NADP (NADPH) in the absence of presence of CoA or acetyl-CoA. NADP and mevalonate were also used as product inhibitors of the reduction of mevaldate. In the reduction of mevaldate to mevalonate, coenzyme A and acetyl-CoA decreased the Km for mevaldate 30- and 3-fold, respectively. Both compounds increased the Vmax 1.5-fold. These results suggest that CoA is an allosteric activator for the second reductive step and that it acts by enhancing the binding of mevaldate. The intersecting patterns obtained from initial velocities and the patterns produced by product inhibitions suggest the following features of the mechanism. The binding of substrates and release of products proceeds sequentially in both reductive steps, and is ordered throughout or random with respect to the binding of the beta-hydroxy-beta-methylglutaryl-coenzymeA and the first NADPH. The binding of NADPH enhances the binding of the beta-hydroxy-beta-methylglutaryl portion of the CoA ester and the binding of free mevaldate, whereas the binding of NADP leads to an increased affinity of the enzyme for the hemithioacetal (of mevaldate and CoA) and for mevalonate. Thus, the replacement of NADP by NADPH after the first reductive step promotes the conversion of the hemithioacetal to the free carbonyl form, which is then rapidly reduced. The products, CoA and mevalonic acid, of the second reductive step leave the enzyme before the release of the second NADP. This release of the last product is probably the rate-limiting step for the overall process.

The short-term regulation of rat liver acetyl-CoA carboxylase by glucagon has been studied in hepatocytes from rats that had been fasted and refed a fat-free diet. Glucagon inhibition of the activity of this enzyme can be accounted for by a direct correlation between phosphorylation, polymer-protomer ratio, and activity. Glucagon rapidly inactivates acetyl-CoA carboxylase with an accompanying 4-fold increase in the phosphorylation of the enzyme and 3-fold increase in the protomer-polymer ratio of enzyme protein. Citrate, an allosteric activator of acetyl-CoA carboxylase required for enzyme activity, has no effect on these phenomena, indicating a mechanism that is independent of citrate concentration within the cell. The observation of these effects of glucagon on acetyl-CoA carboxylase activity is absolutely dependent upon the minimization of proteolytic degradation of the enzyme after cell lysis. Therefore, for the first time, an interrelationship has been demonstrated between phosphorylation, protomer-polymer ratio, and citrate for the inactivation of acetyl-CoA carboxylase by glucagon.

A feeding trial was conducted to evaluate the effects of dietary trans unsaturated fatty acids (trans fat) and of the interplay of dietary saturated fatty acids (saturated fat), cis unsaturated fatty acids, (cis fat) and trans fat on tissue lipids, particularly those effects suggestive of angiotoxicity. Swine were fed for 10 months a diet containing 17% added fat. Seven blends of varying proportions of the 3 fat components provided sufficient sample points to permit an examination of the interplay. Parameters under study included weight gain, serum cholesterol and triglyceride concentrations, lipoprotein lipid profile, total lipid and cholesterol concentrations of liver, heart and aorta, fatty acid composition of liver and aorta lipids and hepatic fatty acid synthesis and cholesterol synthesis and oxidation. Fat blends containing disproportionately high levels of saturated or cis fat generally elicited responses consistent with results reported by others. The notable exception was the serum cholesterol concentration. Throughout the study, the swine were hypercholesterolemic. Swine fed the high saturated fat blend had serum cholesterol levels equal to those swine fed the high cis fat blend. Serum cholesterol levels in the swine fed the other fat blends were more elevated. Another apparent anomaly was the lower concentration of lipid in the aortas of swine fed the high-saturated fat diet. The impact of the trans fat was modulated by the relative proportions of saturated and cis fat in the diet. The impact of trans fat was of greater magnitude for most parameters when the fat blend was low in saturated fat. The sole parameter suggestive of trans fat-mediated angiotoxicity was the distribution of lipids in lipoprotein fractions. Swine fed diets containing trans fat had lower relative proportions of the alpha-lipoprotein lipids. Although hypercholesterolemic, the high fat diets were not overtly angiotoxic except when fed to swine that carried a specific immunogenetically-defined low density lipoprotein.

Four cDNA clones have been identified by hybrid-select translation to contain the sequences complementary to fatty acid synthetase mRNA. The restriction mapping of these clones indicated that three of these, pFAS-7, pFAS-17 and pFAS-18, have sequences in common, and a fourth, pFAS-15, did not hybridize with the others, suggesting sequence to another region of the mRNA. Northern analysis of cytoplasmic poly(A) +RNA showed the presence of two bands at 9.2 Kb and 8.4 Kb. Similar analysis of nuclear RNA also showed the presence of two bands at 14 and 11 Kb. These probably represent unprocessed transcripts. Southern analysis of genomic DNA digested with EcoRI, BamHI, HindIII and PstI indicate the presence of a single gene copy for fatty acid synthetase.

Proteolysis of pigeon liver fatty acid synthetase with elastase results in the quantitative cleavage of the thioesterase component from the enzyme complex. This thioesterase component is two or three times more active catalytically in the isolated state than in the native fatty acid synthetase, and its activity is not affected by the presence or absence of reducing thiols. The proteolytically cleaved thioesterase is separated from the core enzyme in one step by size-exclusion chromatography on a Sephadex G-75 column. The peptide obtained by gel permeation is homogeneous with respect to size and charge, as shown by polyacrylamide gel electrophoresis in the presence and absence of SDS. Size-exclusion chromatography on Bio-Gel A 0.5 m and Sephadex G-75 columns, sucrose density gradient ultracentrifugation, and N-terminal amino acid analysis also indicate that the proteolytically cleaved thioesterase is homogeneous. The sedimentation coefficient of the thioesterase is approximately 2.9 S. Proteolytic cleavage with elastase also quantitatively releases the [1,3-14C]- or [1,3-3H]diisopropylphosphofluoridate-labeled thioesterase component from the correspondingly labeled fatty acid synthetase. Binding studies with 14C- or 3H-labelled diisopropylphosphofluoridate and fatty acid synthetase show that 2 mol of the label are bound per mol of the enzyme when complete loss of fatty acid-synthesizing activity occurs. The molecular weight of the thioesterase component is estimated to be 36000 by size-exclusion chromatography, SDS-polyacrylamide gel electrophoresis and amino acid analysis.

During the late summer to fall of 1987, Caribbean reef corals experienced an intense and widespread discoloration event described as bleaching. Contrary to initial predictions, most bleached corals did not die. However, energy input from zooxanthellae decreased, as estimated from: (i) delta(13)C values, a measure of the discrimination against (13)C in (12)C/(13)C assimilation, of skeletal aragonite; (ii) in situ photosynthesis-irradiance measurements; (iii) and tissue biomass parameters of Montastraea annularis and Agaricia lamarcki. The delta(18)O signal, a measure of the discrimination against (18)O in (16)O/(18)O assimilation, from M. annularis skeletons demonstrated that this event coincided with abnormally elevated water temperatures.