南极磷虾种群生物学研究进展III-摄食

鉴于南极磷虾在南极食物网中所处的关键地位,其摄食活动对南大洋海洋生态系统有着极为重要的影响。南极磷虾食物组成因季节、空间等不同而存在差异,且摄食对象的分类和鉴别也存在着较大困难,选食机制目前尚有不同意见。本文从摄食对象、摄食方式、选食机制及摄食率等方面对近百年来南极磷虾摄食生态学研究进行了总结和归纳,以期为国内外学者开展相关研究提供基础信息,并为进一步开展其摄食生态学研究提供科学思路。     

Unexpected similarity in RBC DHA and AA levels between bottlenose dolphins and humans

BackgroundThe Omega-3 Index [red blood cell (RBC) content of eicosapentaenoic acid (EPA)+docosahexaenoic acid (DHA)] is inversely related to risk of cardiovascular disease in humans. In the U.S., the average Omega-3 Index is about 4–6% of RBC fatty acids, whereas in Japan it is 9–10%. The range of physiologically-possible levels for the Omega-3 Index in other mammals is unknown.ObjectiveTo compare the RBC fatty acid composition of a common piscivorous mammal, the bottlenose dolphin (Tursiops truncatus), with that of (U.S.) humans, and to examine the extent to which dietary fatty acid patterns were reflected in RBCs.MethodsRBCs were isolated from routine blood samples collected from 35 healthy dolphins at two display facilities and were analyzed by gas chromatography. For humans, historic, deidentified RBC fatty acid data from our laboratory were used (n=11,329; mean age 58).ResultsThe mean Omega-3 Index of the dolphins was 19.9% compared with 6.0% for humans. EPA levels were 15.3% vs 1.2%, respectively, but DHA levels were virtually identical (4.6% vs 4.8%). Linoleic acid (LNA) levels were much lower in dolphins vs humans (0.5% vs 12.5%) whereas arachidonic acid (ARA) levels were similar (12.3% vs 14.5%). In a subgroup of humans with an Omega-3 Index in the >99.2 percentile, the mean index was similar to that of the dolphins. Based on an analysis of their food, the dolphins consumed about 60 g of EPA+DHA per day as compared to about 0.1 g in humans.ConclusionDolphins have an Omega-3 Index that is (only) 3–4× higher than that of U.S. adults despite their intake of EPA+DHA being about 165× higher (as a percent of kcal). RBC, EPA and LNA levels are relatively more reflective of dietary intakes than are DHA and ARA levels. The mechanisms by which certain fatty acid levels appear to be fixed and others may vary in RBC membranes are unknown.     

湖北后河自然保护区果子狸食物组成初步研究

2005年4~10月在湖北后河自然保护区,采集果子狸(Paguma larvata)粪便,应用频次法进行分析,再结合胃内容物分析,同时根据采食痕迹,对该物种春、夏和秋季的食物组成进行了研究。结果表明,果子狸食物组分以水果类植物(37·5%)、节肢动物(25·2%)为主,其次为非水果类植物(9·9%)和小型哺乳动物(7·1%)等。果子狸食物组成在不同的季节间有一定差异。春季,果子狸食物组成中以节肢动物(35·6%)为主,其次是非水果类植物(26·7%)和小型哺乳动物(15·6%),另外还有少量的软体动物(4·4%)和水果类植物(8·9%);夏季,果子狸食物组成转为以水果类植物(39·8%)和节肢动物(29·2%)为主,此外还有少量非水果类植物(2·7%)和小型哺乳动物(5·3%),以及少量鸟类(0·9%);秋季,果子狸食物组分中含有大量的水果类植物(63·9%),其他食物类别比例很小,包括鸟类(1·0%)、小型哺乳动物(0·6%)和爬行动物(0·4%)等。食物多样性指数显示,随着季节变化,果子狸食物多样性逐渐下降,小型哺乳动物和非水果类植物在其食性组成中逐渐下降,而水果类植物则转为最主要食物。     

Deficiency of Oncostatin M Receptor β (OSMRβ) Exacerbates High-fat Diet-induced Obesity and Related Metabolic Disorders in Mice

Oncostatin M (OSM) belongs to the IL-6 family of cytokines and has diverse biological effects, including the modulation of inflammatory responses. In the present study we analyzed the roles of OSM signaling in obesity and related metabolic disorders. Under a high-fat diet condition, OSM receptor β subunit-deficient (OSMRβ^−/−) mice exhibited increases in body weight and food intake compared with those observed in WT mice. In addition, adipose tissue inflammation, insulin resistance, and hepatic steatosis were more severe in OSMRβ^−/− mice than in wild-type (WT) mice. These metabolic phenotypes did not improve when OSMRβ^−/− mice were pair-fed with WT mice, suggesting that the effects of OSM signaling on these phenotypes are independent of the increases in the body weight and food intake. In the liver of OSMRβ^−/− mice, the insulin-induced phosphorylation of p70 S6 kinase remained intact, whereas insulin-induced FOXO1 phosphorylation was impaired. In addition, OSMRβ^−/− mice displayed a higher expression of genes related to de novo lipogenesis in the liver than WT mice. Furthermore, treatment of genetically obese ob/ob mice with OSM improved insulin resistance, adipose tissue inflammation, and hepatic steatosis. Intraportal administration of OSM into ob/ob mice activated STAT3 and increased the expression of long-chain acyl-CoA synthetase (ACSL) 3 and ACSL5 with decreased expression of fatty acid synthase in the liver, suggesting that OSM directly induces lipolysis and suppresses lipogenesis in the liver of obese mice. These findings suggest that defects in OSM signaling promote the deterioration of high-fat diet-induced obesity and related metabolic disorders.     

The impact of the Philadelphia beverage tax on employment: A synthetic control analysis

Prevalence of obesity and other diet-related non-communicable diseases (NCDs) have continued to rise for decades in the United States. In addition to adverse health consequences, these diseases have led to substantial economic costs in the form of medical expenses and productivity losses. To address the rise in NCDs, excise taxes on sugar-sweetened beverages (SSBs) are increasingly proposed and implemented as a policy tool for improving dietary intake and population health. To date, few empirical studies have evaluated the potential unintended economic effects of these taxes. In this paper, we examine the impact of the Philadelphia, PA, sweetened beverage tax (applied to both SSBs and artificially sweetened beverages) on employment in key industries that sell sweetened beverages as well as on net total employment. Drawing on monthly employment count data from the Bureau of Labor Statistics from January 2012 through June 2019, we conducted a synthetic control analysis of total, private sector, limited-service restaurant, and convenience store employment. The synthetic controls reproduced nearly identical pre-tax employment trends to Philadelphia and had similar values of important predictors. In the post-tax period, Philadelphia employment was not lower, on average, than the synthetic control employment for each outcome. Placebo tests suggested a null effect of the tax, and the results were robust to changes in predictors and control site criteria. Overall, we did not find that the sweetened beverage tax resulted in job losses up to two and a half years after the tax was implemented. These findings are consistent with other peer-reviewed modeling and empirical papers on the employment and unemployment effects of sweetened beverage taxes.     

The role of genotype and diet in shaping gut microbiome in a genetic vitamin A deficient mouse model

Multifactors have been reported to affect the gut microbiome, including genotype, age, diet, and nutrition. However, few reports have investigated the relative capacity of different factors to shape the gut microbiome in a single study. Our design used a genetic vitamin A-deficient mouse model, the Rbp4^?/? mouse, feeding with the low vitamin A diets at different ages of initiation (4 or 7 weeks) for 28 days. Fecal samples were collected for bacterial profiling at seven time points after diet controlling. With Rbp4 depletion, Akkermansia decreased and Bacteroides increased, whereas Desulfovibrio, Barnesiella, Clostridium_XlVa, and Lactobacillus fluctuated. The bacterial community swiftly adjusted with the vitamin A-deficient diet administration and gradually changed (e.g., decrease of Barnesiella and increase of Desulfovibrio). Age exerted a relatively weaker but long-last influence. At an earlier age to feed a vitamin A-deficient diet, a higher microbial dysbiosis index will be valued. Of note, the shaping effects of diet and age on the bacterial community varied with the difference of genotype, which might indicate a greater role of genotype than diet and age in shaping the gut microbiome.     

Insulin therapy and its consequences for the mother,foetus, and newborn in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a disease characterised by glucose intolerance and first diagnosed in pregnancy. This condition relates to an anomalous placental environment and aberrant placental vascular function. GDM-associated hyperglycaemia changes the placenta structure leading to abnormal development and functionality of this vital organ. Aiming to avoid the GDM-hyperglycaemia and its deleterious consequences in the mother, the foetus and newborn, women with GDM are firstly treated with a controlled diet therapy; however, some of the women fail to reach the recommended glycaemia values and therefore they are passed to the second line of treatment, i.e., insulin therapy. The several protocols available in the literature regarding insulin therapy are variable and not a clear consensus is yet reached. Insulin therapy restores maternal glycaemia, but this beneficial effect is not reflected in the foetus and newborn metabolism, suggesting that other factors than d-glucose may be involved in the pathophysiology of GDM. Worryingly, insulin therapy may cause alterations in the placenta and umbilical vessels as well as the foetus and newborn additional to those seen in pregnant women with GDM treated with diet. In this review, we summarised the variable information regarding indications and protocols for administration of the insulin therapy and the possible outcomes on the function and structure of the foetoplacental unit and the neonate parameters from women with GDM.     

Phosphate toxicity and tumorigenesis

In this article, we briefly summarized evidence that cellular phosphate burden from phosphate toxicity is a pathophysiological determinant of cancer cell growth. Tumor cells express more phosphate cotransporters and store more inorganic phosphate than normal cells, and dysregulated phosphate homeostasis is associated with the genesis of various human tumors. High dietary phosphate consumption causes the growth of lung and skin tumors in experimental animal models. Additional studies show that excessive phosphate burden induces growth-promoting cell signaling, stimulates neovascularization, and is associated with chromosome instability and metastasis. Studies have also shown phosphate is a mitogenic factor that affects various tumor cell growth. Among epidemiological evidence linking phosphate and tumor formation, the Health Professionals Follow-Up Study found that high dietary phosphate levels were independently associated with lethal and high-grade prostate cancer. Further research is needed to determine how excessive dietary phosphate consumption influences initiation and promotion of tumorigenesis, and to elucidate prognostic benefits of reducing phosphate burden to decrease tumor cell growth and delay metastatic progression. The results of such studies could provide the basis for therapeutic modulation of phosphate metabolism for improved patient outcome.     

Caloric restriction counteracts chemotherapy-induced inflammation and increases response to therapy in a triple negative breast cancer model

Triple negative breast cancer (TNBC) is a heterogeneous disease that has no available targeted therapies. Previously, we have shown that caloric restriction (CR) can augment the effects of radiation therapy in a TNBC mouse model. To build upon this, we now present data regarding the combination of chemotherapy and CR in the same 4T1 model. Chemotherapy can induce inflammation that breeds resistance to therapy. We propose CR as a mechanism to decrease chemotherapy-induced inflammation and increase efficacy of therapy. 12-week old Balb/c mice were orthotopically injected with a syngeneic triple negative breast cancer cell line (4T1) and were treated in one of six cohorts: ad lib fed (AL), 30% reduction in calorie intake (CR), cisplatin or docetaxol alone or a combination CR+cisplatin/docetaxol. Mice in the cohorts receiving chemotherapy+CR had longer overall survival (12 ± 2 days) as compared to the AL group. These mice also demonstrated less lung metastases at the final time point of in vivo imaging. In addition, downregulation of the IGF-1R and IRS signaling pathways were noted most significantly in those mice receiving combination therapy. Lastly, serum from these mice demonstrated an increase in inflammatory cytokines TNF-α and IL-1β in response to chemotherapy alone. This increase was dampened by the addition of CR. Taken together, these data suggest that while chemotherapy is effective in TNBC, it can cause inflammation, which can be a driver of resistance to therapy. This chemotherapy-induced inflammation can be reversed with the use of CR as a nontoxic adjunct to treatment.     

l-arginine supplementation of milk liquid or dry diets fed to pigs after weaning has a positive effect on production in the first three weeks after weaning at 21 days of age

A total of 48, 21-day-old weaned pigs, was used in a 2 × 2 factorial arrangement of treatments with the factors being diet type (milk liquid replacer vs. dry feed) and l-arginine (ARG) supplementation (0 vs. 6 g ARG/kg) to test the hypothesis that dietary supplementation with ARG would increase performance of pigs after weaning. Pigs were fed the experimental diets for 10 d (days) after weaning and then transitioned over a 3-d period to a dry Phase II diet fed in meal form devoid of supplemental ARG. The study ended at d 21. There were five replicates (pens) per treatment (a total of 12 pigs per treatment). Blood samples were collected from two pigs per replicate on d 7 and 16 of the experiment, and free amino acids (AA) and plasma urea nitrogen (PUN) levels analysed. Milk-fed pigs outperformed (P<0.001) dry-fed pigs for the first 10 d of the experiment as well as for the total 21-d period. At d 7, milk-fed pigs had higher (P<0.05) levels of most free indispensable and dispensable amino acids in their plasma. In both the milk-fed and dry-fed pigs supplemented with ARG, average daily feed intake (ADFI, P<0.05) and average daily gain (ADG, P<0.05) were increased during the dietary transition period (d 11–14), when pigs were being changed to the Phase II diet. The difference in production in the transition period caused a tendency for ARG-supplemented pigs to eat more feed (P<0.1) and grow faster (P<0.5) over the 21-d experimental period. Pigs supplemented with ARG had higher plasma ARG levels (P<0.05) at d 7 after weaning and lower plasma urea levels (P<0.05) at both d 7 and 16 after weaning. These data show the benefits of feeding a milk liquid diet as well as of ARG supplementation after weaning on production indices.