Differential expression of six genes and correlation with fatness traits in a unique broiler population

Previous results from genome wide association studies (GWASs) in chickens divergently selected for abdominal fat content of Northeast Agricultural University (NEAUHLF) showed that many single nucleotide polymorphism (SNP) variants were associated with abdominal fat content. Of them, six top significant SNPs at the genome level were located within SRD5A3, SGCZ, DLC1, GBE1, GALNT9 and DNAJB6 genes. Here, expression levels of these six candidate genes were investigated in abdominal fat and liver tissue between fat and lean broilers from the 14th generation population of NEAUHLF. The results showed that expression levels of SRD5A3, SGCZ and DNAJB6 in the abdominal fat and SRD5A3, DLC1, GALNT9, DNAJB6 and GBE1 in the liver tissue differed significantly between the fat and lean birds, and were correlated with abdominal fat traits. The findings will provide important references for further function investigation of the six candidate genes involved in abdominal fat deposition in chickens.     

Genetic analysis of abdominal fat distribution in SM/J and A/J mice

Each abdominal fat depot, such as mesenteric or epididymal, differently contributes to the development of insulin resistance. The aim of this study was to identify the genetic regions that contribute to fat accumulation in epididymal/mesenteric fat and to examine whether or not the genetic regions that affect glucose metabolism and body fat distribution are coincident. We previously mapped a major quantitative trait locus (QTL) (T2dm2sa) for impaired glucose tolerance on chromosome 2 and revealed that SM.A-T2dm2sa congenic mice showed not only glucose tolerance but also fat accumulation. In the present study, to identify the loci/genes that control the accumulation of abdominal fat, we perfomed QTL analyses of epididymal/mesenteric fat weight by using (A/J×SM.A-T2dm2sa)F2 mice in which the effect of T2dm2sa was excluded. As a result, two highly significant QTLs for mesenteric fat, as well as three significant QTLs for epididymal/mesenteric fat, were mapped on the different chromosomal regions. This suggests that the fat accumulations in individual fat depots are controlled by distinct genomic regions. Our comparison of these QTLs for abdominal fat distribution with those for glucose metabolism revealed that the major genetic factors affecting body fat distribution do not coincide with genetic factors affecting glucose metabolism in (A/J×SM.A-T2dm2sa)F2.     

Intake of dietary fats and colorectal cancer risk: Prospective findings from the UK Dietary Cohort Consortium

Introduction: Epidemiologic evidence for an association between colorectal cancer (CRC) risk and total dietary fat, saturated fat (SF), monounsaturated fat (MUFA) and polyunsaturated fat (PUFA) is inconsistent. Previous studies have used food frequency questionnaires (FFQ) to assess diet, but data from food diaries may be less prone to severe measurement error than data from FFQ. Methods: We conducted a case–control study nested within seven prospective UK cohort studies, comprising 579 cases of incident CRC and 1996 matched controls. Standardized dietary data from 4- to 7-day food diaries and from FFQ were used to estimate odds ratios for CRC risk associated with intake of fat and subtypes of fat using conditional logistic regression. We also calculated multivariate measurement error corrected odds ratios for CRC using repeated food diary measurements. Results: We observed no associations between intakes of total dietary fat or types of fat and CRC risk, irrespective of whether dietary data were obtained using food diaries or FFQ. Conclusion: Our results do not support the hypothesis that intakes of total dietary fat, SF, MUFA or PUFA are linked to risk of CRC.     

The Influence of Bacterial Diet on Fat Storage in C. elegans

Background

The nematode Caenorhabditis elegans has emerged as an important model for studies of the regulation of fat storage. C. elegans feed on bacteria, and various strains of E. coli are commonly used in research settings. However, it is not known whether particular bacterial diets affect fat storage and metabolism.

Methodology/Principal Findings

Fat staining of fixed nematodes, as well as biochemical analysis of lipid classes, revealed considerable differences in fat stores in C. elegans growing on four different E. coli strains. Fatty acid composition and carbohydrate levels differ in the E. coli strains examined in these studies, however these nutrient differences did not appear to have a causative effect on fat storage levels in worms. Analysis of C. elegans strains carrying mutations disrupting neuroendocrine and other fat-regulatory pathways demonstrated that the intensity of Nile Red staining of live worms does not correlate well with biochemical methods of fat quantification. Several neuroendocrine pathway mutants and eating defective mutants show higher or lower fat storage levels than wild type, however, these mutants still show differences in fat stores when grown on different bacterial strains. Of all the mutants tested, only pept-1 mutants, which lack a functional intestinal peptide transporter, fail to show differential fat stores. Furthermore, fatty acid analysis of triacylglycerol stores reveals an inverse correlation between total fat stores and the levels of 15-methylpalmitic acid, derived from leucine catabolism.

Conclusions

These studies demonstrate that nutritional cues perceived in the intestine regulate fat storage levels independently of neuroendocrine cues. The involvement of peptide transport and the accumulation of a fatty acid product derived from an amino acid suggest that specific peptides or amino acids may provide nutritional signals regulating fat metabolism and fat storage levels.     

Depot-specific regulation of autotaxin with obesity in human adipose tissue

Autotaxin (ATX) is a lysophospholipase D involved in synthesis of a bioactive mediator: lysophosphatidic. ATX is abundantly produced by adipocytes and exerts a negative action on adipose tissue expansion. In both mice and humans, ATX expression increases with obesity in association with insulin resistance. In the present study, fat depot-specific regulation of ATX was explored in human. ATX mRNA expression was quantified in visceral and subcutaneous adipose tissue in obese (BMI?>?40?kg/m²; n?=?27) and non-obese patients (BMI?<?25?kg/m²; n?=?10). Whatever the weight status of the patients is, ATX expression was always higher (1.3- to 6-fold) in subcutaneous than in visceral fat. Nevertheless, visceral fat ATX was significantly higher (42?%) in obese than in non-obese patients, whereas subcutaneous fat ATX remained unchanged. In obese patients, visceral fat ATX expression was positively correlated with diastolic arterial blood pressure (r?=?0.67; P?=?0.001). This correlation was not observed with subcutaneous fat ATX. Visceral fat ATX was mainly correlated with leptin (r?=?0.60; P?=?0.001), inducible nitric oxide synthase (r?=?0.58; P?=?0,007), and apelin receptor (r?=?0.50; P?=?0.007). These correlations were not observed with subcutaneous fat ATX. These results reveal that obesity-associated upregulation of human adipose tissue ATX is specific to the visceral fat depot.     

The DNA damage checkpoint protein ATM promotes hepatocellular apoptosis and fibrosis in a mouse model of non-alcoholic fatty liver disease

Steatoapoptosis is a hallmark of non-alcoholic fatty liver disease (NAFLD) and is an important factor in liver disease progression. We hypothesized that increased reactive oxygen species resulting from excess dietary fat contribute to liver disease by causing DNA damage and apoptotic cell death, and tested this by investigating the effects of feeding mice high fat or standard diets for 8 weeks. High fat diet feeding resulted in increased hepatic H₂O₂, superoxide production, and expression of oxidative stress response genes, confirming that the high fat diet induced hepatic oxidative stress. High fat diet feeding also increased hepatic steatosis, hepatitis and DNA damage as exemplified by an increase in the percentage of 8-hydroxyguanosine (8-OHG) positive hepatocytes in high fat diet fed mice. Consistent with reports that the DNA damage checkpoint kinase Ataxia Telangiectasia Mutated (ATM) is activated by oxidative stress, ATM phosphorylation was induced in the livers of wild type mice following high fat diet feeding. We therefore examined the effects of high fat diet feeding in Atm-deficient mice. The prevalence of apoptosis and expression of the pro-apoptotic factor PUMA were significantly reduced in Atm-deficient mice fed the high fat diet when compared with wild type controls. Furthermore, high fat diet fed Atm^−/− mice had significantly less hepatic fibrosis than Atm^+/+ or Atm^+/− mice fed the same diet. Together, these data demonstrate a prominent role for the ATM pathway in the response to hepatic fat accumulation and link ATM activation to fatty liver-induced steatoapoptosis and fibrosis, key features of NAFLD progression.     

First report of the apparent metabolisable energy value of black soldier fly larvae fat used in broiler chicken diets

In the available literature, there are limited data about the energetic value of insect-derived products. In particular, insect fat cannot be used in practical broiler nutrition due to the lack of precise apparent metabolisable energy (AME) value. Therefore, the present study aimed to investigate the AME and apparent metabolisable energy corrected to zero nitrogen balance (AME_N) levels of Hermetia illucens larvae fat for broiler chickens of various ages. A total of 400 1-day-old male Ross 308 chicks were randomly allotted to four dietary groups (10 replicate pens per treatment; 10 birds per pen). The following treatments were applied: HI0 – basal diet without dietary fat inclusion, HI03 – basal diet enriched with 30 g/kg H. illucens larvae fat, HI06 – basal diet enriched with 60 g/kg H. illucens larvae fat, and HI09 – basal diet enriched with 90 g/kg H. illucens larvae fat. Broilers had ad libitum access to mash form feed and water. Excreta samples were collected on d 14, d 28, and d 35. To determine the AME and AME_N values of H. illucens larvae fat, the simple linear regression method was used. The results show that the AME and AME_N values of H. illucens larvae fat for broiler chickens are 9 049 kcal/kg (37.86 MJ/kg) and 9 019 kcal/kg (37.74 MJ/kg), respectively. Additionally, because the birds’ age significantly (P < 0.001) affected the AME and AME_N levels, the implementation of H. illucens larvae fat to broiler diets should be considered in each nutritional period using the recommended regression model AME = 2 559.758 + 62.989 × fat inclusion (%) + 7.405 × day of age and AME_N = 2 543.2663 + 62.8649 × fat inclusion (%) + 7.3777 × day of age. The present data emphasised that the H. illucens larvae fat metabolisable energy is similar to that of soybean oil.     

Fat source and dietary forage-to-concentrate ratio influences milk fatty-acid composition in lactating cows

On the basis of the potential benefits to human health there is an increased interest in producing milk containing lower-saturated fatty acid (SFA) and higher unsaturated fatty acid (FA) concentrations, including cis-9 18:1 and cis-9, trans-11-conjugated linoleic acid (CLA). Twenty-four multiparous Holstein cows were used in two experiments according to a completely randomized block design, with 21-day periods to examine the effects of incremental replacement of prilled palm fat (PALM) with sunflower oil (SFO) in high-concentrate diets containing 30 g/kg dry matter (DM) of supplemental fat (Experiment 1) or increases in the forage-to-concentrate (F : C) ratio from 39 : 61 to 48 : 52 of diets containing 30 g/kg DM of SFO (Experiment 2) on milk production, digestibility and milk FA composition. Replacing PALM with SFO had no effect on DM intake, but tended to increase organic matter digestibility, yields of milk, protein and lactose, and decreased linearly milk fat content. Substituting SFO for PALM decreased linearly milk fat 8:0 to 16:0 and cis-9 16:1, and increased linearly 18:0, cis-9 18:1, trans-18:1 (Δ4 to 16), 18:2 and CLA concentrations. Increases in the F : C ratio of diets containing SFO had no effect on intake, yields of milk, milk protein or milk lactose, lowered milk protein content in a quadratic manner, and increased linearly NDF digestion and milk fat secretion. Replacing concentrates with forages in diets containing SFO increased milk fat 4:0 to 10:0 concentrations in a linear or quadratic manner, decreased linearly cis-9 16:1, trans-6 to -10 18:1, 18:2n-6, trans-7, cis-9 CLA, trans-9, cis-11 CLA and trans-10, cis-12 CLA, without altering milk fat 14:0 to 16:0, trans-11 18:1, cis-9, trans-11 CLA or 18:3n-3 concentrations. In conclusion, replacing prilled palm fat on with SFO in high-concentrate diets had no adverse effects on intake or milk production, other than decreasing milk fat content, but lowered milk fat medium-chain SFA and increased trans FA and polyunsaturated FA concentrations. Increases in the proportion of forage in diets containing SFO increased milk fat synthesis, elevated short-chain SFA and lowered trans FA concentrations, without altering milk polyunsaturated FA content. Changes in fat yield on high-concentrate diets containing SFO varied between experiments and individual animals, with decreases in milk fat secretion being associated with increases in milk fat trans-10 18:1, trans-10, cis-12 CLA and trans-9, cis-11 CLA concentrations.     

Lipid composition of the fat body and haemolymph and its relation to lipid release in Oncopeltus fasciatus

Lipid composition of the fat body and haemolymph of male milkweed bug, Oncopeltus fasciatus, was determined. Triglycerides were the predominant lipids of the fat body while diglycerides accounted for the major lipid in the haemolymph. Sterols, sterol esters, and non-esterified fatty acids were present in both fat body and haemolymph besides triglycerides and diglycerides. Only traces of monoglycerides were detected.Gas chromatographic analysis of the fatty acids revealed a difference in the fatty acid composition between fat body and haemolymph glycerides and sterol esters. Oleate and linoleate were the predominant unsaturated fatty acids in both fat body and haemolymph lipids and in the milkweed seeds as well.When fat body was labelled in vivo and in vitro with ¹⁴C-palmitate, the fatty acid was incorporated largely into the triglycerides. When the prelabelled fat body was incubated with a medium containing haemolymph the fat body released lipids mainly as diglycerides. Some radioactivity was observed in the triglycerides and non-esterified fatty acids also.Electrophoretic analysis of the incubation medium containing the haemolymph revealed that the released lipids were bound to three haemolymph lipoprotein bands. Lipid mobilization, release, and transport in Oncopeltus are discussed in relation to studies on other insects.     

Yolk polypeptide synthesis in the fat body of Sarcophaga bullata: Localization,hormonal induction and cell-free translation

The fat body of adult Sarcophaga bullata consists of different cell-types. The yolk polypeptides (YPs) are localized in secretory granules in the cytoplasm of female trophocyte fat body cells while the oenocytes and larval fat body cells are immunonegative. An antiserum against the larval serum protein 1 of Drosophila crossreacts on immunoblotting with several polypeptide bands in the haemolymph with mol. wt ∼80 kD. This antiserum specifically reacts with some storage granules of the persisting larval fat body cells and not with the other fat body cell types. The trophocyte fat body cells of male Sarcophaga treated with 20-OH-ecdysone, display a similar granular type of immunoreaction with an anti-YP antiserum as in vitellogenic females. Moreover, 20-OH-ecdysone induced in the fat body of males, in contrast to methoprene, synthesis of mRNA coding for YPs to a level as high as that in vitellogenic females, as shown in the reticulocyte lysate cell-free system.     

The role of SOCS2 in recombinant human growth hormone (rhGH) regulating lipid metabolism in high-fat-diet-induced obesity mice

In addition to regulate body growth and development process, growth hormone (GH) also involved in lipid metabolism, decreasing fat mass and improving lipolysis. To normal mice, GH could reduce their fat content, but events turned uncertain coming to the pattern of feeding high-fat-diet. In order to investigate the role of GH in adipogenesis of mice with high-fat-diet, the high-fat-diet feeding mice were randomly assigned into three groups and treated with recombinant human growth hormone (rhGH) and the somatostatin analogue octreotide respectively. Results demonstrated that both rhGH and octreotide could reduce the body weight but the trends diminished in the end. HDL-C level was increased in octreotide treated groups but the activity of lipase was increased significantly in both two groups. RhGH remarkable increased the expression of SOCS2, FAS (P < 0.01) and SREBP-1c (P < 0.05), decreased the expression of SOCS1, SOCS3 (P < 0.05) and HSL (P < 0.01) in subcutaneous fat mass. In visceral fat tissue, all genes were increased except SOCS2 (P < 0.01), at the same time the visceral fat mass was decreased. The protein phosphorylation of JAK2 and STAT5 which were treated with octreotide were increased in subcutaneous fat, visceral fat and liver (P < 0.01) and were increased significant in visceral fat by rhGH treated (P < 0.01). In liver, only JAK2 protein phosphorylation was raised (P < 0.01). In conclusion, rhGH and octreotide could decrease the whole body mass before 6 days; the trend was weaken in later period with high-fat-diet. RhGH could increase the subcutaneous fat mass and reduce the visceral fat mass, and SOCS2 might be involved in regulation of the mechanism through JAK2/STAT5 signaling pathway.     

The influence of larval fat body on wing disk development in vitro

The effects are noted of various fat body treatments on betaecdysone-induced cuticle deposition in cultured wing disks of Plodia interpunctella. The percentage of disks which responded to hormone treatment in vitro depended upon the age of the disk, the amount of fat body, the time the medium was incubated with fat body, and the time the disks were exposed to beta-ecdysone in fat body-conditioned medium. Fat body from pharate pupae did not stimulate disk development.     

Diet-Induced Obesity Promotes Colon Tumor Development in Azoxymethane-Treated Mice

Obesity is an important risk factor for colon cancer in humans, and numerous studies have shown that a high fat diet enhances colon cancer development. As both increased adiposity and high fat diet can promote tumorigenesis, we examined the effect of diet-induced obesity, without ongoing high fat diet, on colon tumor development. C57BL/6J male mice were fed regular chow or high fat diet for 8 weeks. Diets were either maintained or switched resulting in four experimental groups: regular chow (R), high fat diet (H), regular chow switched to high fat diet (RH), and high fat diet switched to regular chow (HR). Mice were then administered azoxymethane to induce colon tumors. Tumor incidence and multiplicity were dramatically smaller in the R group relative to all groups that received high fat diet at any point. The effect of obesity on colon tumors could not be explained by differences in aberrant crypt foci number. Moreover, diet did not alter colonic expression of pro-inflammatory cytokines tumor necrosis factor-α, interleukin-6, interleukin-1β, and interferon-γ, which were measured immediately after azoxymethane treatment. Crypt apoptosis and proliferation, which were measured at the same time, were increased in the HR relative to all other groups. Our results suggest that factors associated with obesity – independently of ongoing high fat diet and obesity – promote tumor development because HR group animals had significantly more tumors than R group, and these mice were fed the same regular chow throughout the entire carcinogenic period. Moreover, there was no difference in the number of aberrant crypt foci between these groups, and thus the effect of obesity appears to be on subsequent stages of tumor development when early preneoplastic lesions transition into adenomas.     

<Emphasis Type="Italic">HMG1A</Emphasis> and <Emphasis Type="Italic">PPARG</Emphasis> are differently expressed in the liver of fat and lean broilers

The expression of nine functional candidates for QT abdominal fat weight and relative abdominal fat content was investigated by real-time polymerase chain reaction (PCR) in the liver, adipose tissue, colon, muscle, pituitary gland and brain of broilers. The high mobility group AT-hook 1 (HMG1A) gene was up-regulated in liver with a ratio of means of 2.90 (P?≤?0.01) in the «fatty» group (relative abdominal fat content 3.5?±?0.18%, abdominal fat weight 35.4?±?6.09 g) relative to the «lean» group (relative abdominal fat content 1.9?±?0.56%, abdominal fat weight 19.2?±?5.06 g). Expression of this gene was highly correlated with the relative abdominal fat content (0.70, P?≤?0.01) and abdominal fat weight (0.70, P?≤?0.01). The peroxisome proliferator-activated receptor gamma (PPARG) gene was also up-regulated in the liver with a ratio of means of 3.34 (P?≤?0.01) in the «fatty» group relative to the «lean» group. Correlation of its expression was significant with both the relative abdominal fat content (0.55, P?≤?0.05) and the abdominal fat weight (0.57, P?≤?0.01). These data suggest that the HMG1A and PPARG genes were candidate genes for abdominal fat deposition in chickens. Searching of rSNPs in regulatory regions of the HMG1A and PPARG genes could provide a tool for gene-assisted selection.     

Synthesis and release of proteins from cultured larval fat body of the southwestern corn borer,Diatraea grandiosella

The larval fat body of the southwestern corn borer, Diatraea grandiosella, was cultured in vitro to examine the relationship between proteins present in the fat body, those released into the medium, and those present in the haemolymph. While the incorporation of [³H]leucine into fat body proteins was high in last instar pre-diapausing and non-diapausing larvae, it fell in early diapausing larvae to about 11% of that found in prediapausing larvae. Incorporation of [³H]leucine into the diapause-associated protein of the fat body increased gradually in pre-diapausing larvae and reached a maximum in newly-diapaused larvae at a time when the incorporation of [³H]leucine into other proteins of the fat body had declined. The proteins released from the cultured fat body showed identical electrophoretic properties and close immunochemical relationships to most of those present in the haemolymph. Small amounts of the diapause-associated protein were released in vitro from the fat body of larvae of different ages in diapause. Lipophorin was also released in vitro from the fat body of non-diapausing and diapausing larvae, and shown to be immunochemically identical to the lipophorin present in the haemolymph.     

Effect of lysophospholipids in diets differing in fat contents on growth performance,nutrient digestibility,milk composition and litter performance of lactating sows

It is well known that energy plays an important role in sow growth and development. Increasing the utilization of lipids will be beneficial to sows. Emulsifiers are substances which stabilize mixtures and prevent oil and water from separating, thereby enhancing the digestion of lipids. This study was conducted to evaluate the effect of dietary emulsifier (lysophospholipids (LPL)) supplementation in diets differing in fat contents on growth performance, nutrient digestibility and milk composition in lactating sows, as well as performance and fecal score in piglets. A total of 32 multiparous sows (Landrace×Yorkshire) were used in a 21-day experiment. On day 110 of gestation, sows were weighed and moved into the farrowing facility, randomly assigned in a 2×2 factorial arrangement according to their BW with two levels of LPL (0 and 30 mg/kg) and two levels of fat (4.75% and 2.38% fat; 13.66 and 13.24 MJ/kg). BW loss and backfat thickness loss were decreased (P<0.05) by LPL supplementation. Backfat thickness at weaning was higher (P<0.05) in sows fed LPL supplementation diets. The apparent total tract digestibility of dry matter, nitrogen, gross energy and crude fat in sows fed LPL diets was increased (P<0.05) compared with those fed non-LPL diets. Sows fed the high-fat diets had higher (P<0.05) milk fat on day 10 and milk lactose on day 20 than those fed the low-fat diets. Milk fat and lactose concentrations in LPL supplementation treatments was increased (P<0.05) compared with non-LPL treatments on day 10 and day 20, respectively. Positive interaction effects (P<0.05) between fat and LPL were observed for milk fat concentration on day 10. In conclusion, LPL addition decreased BW loss and backfat thickness loss, improved nutrient digestibility and milk fat as well as milk lactose concentrations. In addition, there was a complementary positive effect of dietary fat and LPL supplementation on milk fat concentration in lactating sows.     

Linking cellular zinc status to body weight and fat mass: mapping quantitative trait loci in Znt7 knockout mice

Zinc transporter 7 (Znt7, Slc30a7) knockout (KO) mice display abnormalities in body weight gain and body adiposity. Regulation of body weight and body fat accumulation is complex, involving multiple genetic and environmental factors. To understand how zinc homeostasis influences body weight and fat deposit and to identify quantitative trait loci (QTLs) that link zinc metabolism to growth and adiposity, we conducted a genome-wide mapping study using male F₂ Znt7 KO mice and wild-type (WT) littermates with a mixed 129P1/ReJ and C57BL/6J genetic background. The mice were fed a semi-purified diet containing 30-mg Zn/kg diet at weaning. Body weights and fat pad weights including epididymal, retroperitoneal, and femoral subcutaneous fat pads were measured at 16 weeks of age. We detected two significant QTLs (p < 0.05) for body weight and fat deposit. One was in the F₂ Znt7 KO population and the other in the F₂ WT population. In Znt7 KO mice, the body weight and fat deposit was significantly linked to a locus on chromosome 7 ranging from 64.3 to 78.3 Mb. In WT mice, a significant linkage of retroperitoneal fat mass was found on chromosome 8 between 14.5 and 63.5 Mb. In addition, several other suggestive QTLs (p < 0.63) for body weight and fat accumulation were detected in Znt7 KO and WT mice. In conclusion, the QTLs identified in this study may provide new hints to uncover the genes linking cellular zinc status to growth and body fat accumulation.     

Participation of hemocyte proteinase in dissociation of the fat body on pupation of Sarcophaga peregrina (flesh fly)

In holometabolous insects, larval tissues are degraded on pupation. Previously, we established an in vitro system in which Sarcophaga fat body dissociates in the presence of pupal hemocytes, mimicking the situation in vivo (Kutata et al., J. Insect Physiol.35, 559–565, 1989). In this paper, we showed that chymostatin and phenylmethylsulfonyl fluoride prevented dissociation of fat body in this system. Moreover, of the various proteinases tested, only chymotrypsin degraded the fat body in vitro. These results suggested that a chymotrypsin-like proteinase of hemocytes participates in dissociation of the fat body at the early pupal stage.