Association of daily sitting time and leisure-time physical activity with body fat among U.S.adults

Background:Prolonged sitting and reduced physical activity lead to low energy expenditures.However,little is known about the joint impact of daily sitting time and physical activity on body fat distribution.We investigated the independent and joint associations of daily sitting time and physical activity with body fat among adults.Methods:This was a cross-sectional analysis of U.S.nationally representative data from the National Health and Nutrition Examination Survey2011-2018 among adults aged 20 years or older.Daily sitting time and leisure-time physical activity(LTPA)were self-reported using the Global Physical Activity Questionnaire.Body fat(total and trunk fat percentage)was determined via dual X-ray absorptiometry.Results:Among 10,808 adults,about 54.6%spent 6 h/day or more sitting;more than one-half reported no LTPA(inactive)or less than 150 min/week LTPA(insufficiently active)with only 43.3%reported 150 min/week or more LTPA(active)in the past week.After fully adjusting for sociodemographic data,lifestyle behaviors,and chronic conditions,prolonged sitting time and low levels of LTPA were associated with higher total and trunk fat percentages in both sexes.When stratifying by LTPA,the association between daily sitting time and body fat appeared to be stronger in those who were inactive/insuufficiently active.In the joint analyses,inactive/insuufficiently active adults who reported sitting more than 8 h/day had the highest total(female:3.99%(95%confidence interval(95%CI):3.09%-4.88%);male:3.79%(95%CI:2.75%-4.82%))and trunk body fat percentages(female:4.21%(95%CI:3.09%-5.32%);male:4.07%(95%CI:2.95%-5.19%))when compared with those who were active and sitting less than 4 h/day.Conclusion:Prolonged daily sitting time was associated with increased body fat among U.S.adults.The higher body fat associated with 6 h/day sitting may not be offset by achieving recommended levels of physical activity.

Body Mass Index and Body Fat Percentage in Assessment of Obesity Prevalence in Saudi Adults

Objective To assess the obesity prevalence in body mass index （BMI） and body fat percentage Saudi adults according to the international standards of （BF%）. Methods Five hundred and thirty healthy Saudi adults aged 18-72 years （mean 36.91＋15.22 years） were enrolled in this study. Their body composition was assessed by bioelectrical impendence analysis with a commercially available body composition analyzer. Standard BMI and BF% values were used to define obesity. Results The prevalence of underweight, normal underweight, overweight and obesity in Saudi adults according to the BMI criteria （〈18.5 kg/mz, 18.5-24.4 kg/m2, 25-29.9 kg/m2, 30 k＆/m2 and above, respectively） was 2.5%, 30.2%, 33.6%, and 33.8%, respectively, whereas the obesity prevalence was 60% （n=31g） in Saudi adults according to the BF% criteria （25% for males and 30% for females）, which was significantly higher than that according to BMI criteria. However, it was 50.6% （n=268） when the BMI cutoff point was 27.5 kg/m2, proposed by WHO for the Asian population. Kappa analysis showed that the obesity prevalence defined by BMI and BF% was higher in females than in males （k=0.530 vs k=0.418, P〈O.O001）. The sensitivity and specificity of BMI （30 kg/m2 and 27.5 kg/m2） were 54.1% and 96.7% and 76.4% and 88.2%, respectively, for obesity. A lower BMI cutoff point （26.60 kg/m2） was proposed in this study, which gave the maximum sensitivity （84.3%） and specificity （85.4%）, with a moderate kappa agreement （k=0.686）. Moreover, the obesity prevalence at this cutoff point （56.4%） was significantly higher than that recommended by WHO. Conclusion The specificity of BMI for obesity is high and its sensitivity is low in both sexes. Its sensitivity can be increased by changing BMI cutoff to a lower value. The choice of BF% reference is of great influence for the assessment of obesity prevalence according to the BMI.

Earlier Menarche Can Be an Indicator of More Body Fat:Study of Sexual Development and Waist Circumference in Chinese Girls

Objective This paper aims to study the relationship between body fat and sexual development in Chinese girls with different waist circumference.Methods Six thousand one hundred and fifty six girls aged 6-19 were sampled.Their body weight,height,waist circumference,percentage of body fat and secondary sex characteristics were measured.All the subjects were divided into three groups：low class waist circumference,moderate class waist circumference and high class waist circumference.The menarche percentages were analyzed by using the status method.The menarche ages were analyzed by using the retrospective method.Estimates for mean age at entry into a pubertal stage and menarche were calculated by a probit analysis.Results The incidences of moderate class and high class waist circumstance were 20.94% and 25.27%,respectively.The sexual development of the former was earlier than that of the latter.The percentages of the menarche were detected as high classmoderate classlow class.The menarche ages were expressed as high classmoderate classlow class.Conclusion A close association is found between the waist circumference and sexual development,especially the menarche age.Girls with high class waist circumference are more vulnerable to earlier menarche and excess body fat.It is important to control the occurrence of central obesity through monitoring the change of waist circumference in puberty for girls＇ health.

Percent body fat,but not body mass index,is associated with cardiometabolic risk factors in children and adolescents

Background:The epidemic of overweight and obesity has become a worldwide public health problem.Cardiometabolic diseases may originate in childhood.We investigated the association between percent body fat(PBF)measured by the bioelectrical impedance assay and cardiometabolic risk(CMR)in pediatrics.Methods:This cross-sectional study involved 3819 subjects(6-17 years old)in Shanghai.We assessed the association between PBF and body mass index(BMI)with multiple CMR factors.We examined the risk for cardiometabolic abnormalities attributable to overweight and obesity based on age-and sexspecific PBF Z-scores and BMI Z-scores,respectively.Results:PBF,but not BMI,was positively associated with multiple CMR factors in males and females except for total cholesterol in females(all p<0.05).Compared with the non-overweight group based on PBF,overweight and obese subjects had increasingly higher odds ratio of dyslipidemia(2.90(1.99-4.23),4.59(2.88-7.32)for males and 1.82(1.20-2.75),2.46(1.47-4.11)for females)and elevated blood pressure(BP)(3.26(2.35-4.51),4.55(2.92-7.09)for males and 1.59(1.07-2.34),3.98(2.27-6.17)for females).Obesity females showed a higher likelihood for hyperglycemia(2.19(1.24-3.84))than non-overweight females.In both sexes,the predictive effect of PBF on dyslipidemia and elevated BP in adolescents was better than that in children.For hyperglycemia,the predictive effect of PBF was better in male adolescents and female children.There was no risk difference for cardiometabolic abnormalities attributable to BMI-based obesity categories.Conclusions:PBF but not BMI was associated with CMR.Overweight and obesity categories based on PBF had an increased risk for cardiometabolic abnormalities in children and adolescents.

The Change of Plasm a very Low Density Lipoprotein Concentration Pre-or Post-Feeding and in Conrrelation with Body Fatness Traits in Broiler Chickens

Blood samples were taken from birds,from a commercial line of broiler chicken,being in a fully fed state and in fasting state for 2,4,6 hours respectively at 49 d of age and plasma very low density lipoprotein(VLDL) concentration was measured with turbidimetric assay.The experiment results showed that the variation coefficients of plasma VLDL concentration mersured at four different times were 58.11%,74.39%,69.70%,47.83%,respectively for male broilers,and 41.82%,60.87%.59.26%,50.0%for female broilers respectively.Plasma VLDL concentration decreased with the fasting time.There was a significant positive phenotypic correlation between abdominal fat weight,percentage of abdominal fat and plasma VLDL concentration for the birds being in fully feeding state,and the correlation decreased or no longer existed for the bired being in fasting state.The conclusion was that for practically application of plasma VLDL content selected in broiler chicken breeding,blood samples should be collected from birds being in feeding state.

Bivariate whole-genome linkage scan for bone geometry and total body fat mass

To quantify the genetic correlations between total body fat mass （TBFM） and femoral neck geometric parameters （FNGPs） and, if pos- sible, to detect the specific genomic regions shared by them, bivariate genetic analysis and bivariate whole-genome linkage scan were carried out in a large Caucasian population. All the phenotypes studied were significantly controlled by genetic factors （P 〈 0.001） with the heritabilities ranging from 0.45 to 0.68. Significantly genetic correlations were found between TBFM and CSA （cross-section area）, W （sub-periosteal diameter）, Z （section modulus） and CT （cortical thickness） except between TBFM and BR （buckling ratio）. The peak bivariate LOD scores were 3.23 （20q12）, 2.47 （20p11）, 3.19 （6q27）, 1.68 （20p12）, and 2.47 （7q11） for the five pairs of TBFM and BR, CSA, CT, W, and Z in the entire sample, respectively. Gender-specific bivariate linkage evidences were also found for the five pairs. 6p25 had complete pleiotropic effects on the variations of TBFM ＆ Z in the female sub-population, and 6q27 and 17q11 had coincident link- ages for TBFM ＆ CSA and TBFM ＆ Z in the entire population. We identified moderate genetic correlations and several shared genomic regions between TBFM and FNGPs in a large Caucasian population.

Advances in the research and application of high-intensity focused electromagnetic technology for fat apoptosis and body shaping

With improvements in living standards and advancements in medical technology,the demand for fat reduction and body shaping is increasing.Non-invasive fat reduction and body shaping therapy has gradually become a research hotspot in plastic surgery.High-intensity electromagnetic technology,a non-invasive treatment that can reduce subcutaneous fat and strengthen muscle,has been increasingly applied in clinics in recent years.This article reviews the fat reduction and body shaping mechanism and clinical effects of this equipment and provides a reference for its clinical application.

Phantom of Human Adipose Tissue and Studies of Light Propagation and Light Absorption for Parameterization and Evaluation of Noninvasive Optical Fat Measuring Devices

A method for noninvasive determination of fat and water content in the human body is examined. A spatially resolved spectroscopy method is used which can record low intensity near infrared spectra. This novel approach is compared to other methods for the determination of fat and water content. Monte Carlo simulations of light propagation in tissue are shown and the production and characterization of optical phantoms of adipose tissue are investigated.

Fatty liver is an independent risk factor for gallbladder polyps

BACKGROUND Gallbladder polyps(GBPs)are known to be associated with obesity and metabolic diseases.However,to date,the relationship between GBPs and abnormal body fat distribution,such as fatty liver,visceral obesity,or sarcopenia,has not yet been established.AIM To evaluate whether GBPs are associated with fatty liver,visceral obesity,or sarcopenia.METHODS We retrospectively reviewed the medical records of subjects who underwent various laboratory tests,body composition measurement with a non-invasive body composition analyzer,and abdominal ultrasonography during health checkups.A total of 1405 subjects with GBPs were compared with 2810 age-and sex-matched controls.RESULTS The mean age of the subjects was 46.8±11.7 years,and 63.8%were male.According to multiple logistic regression analysis,the presence of fatty liver[odds ratio(OR)1.413;95%confidence interval(CI)1.218-1.638;P<0.001]was an independent risk factor for GBP,together with low levels of alanine aminotransferase(OR 0.993;95%CI 0.989-0.996;P<0.001).Additionally,fatty liver showed both independent(OR 1.629;95%CI,1.335-1.988;P<0.001)and dosedependent(moderate to severe fatty liver;OR 2.137;95%CI,1.662-2.749;P<0.001)relationship with large GBPs(≥5 mm).The presence of sarcopenia and high visceral fat area were not significantly associated with GBPs.CONCLUSION Fatty liver was found to be closely associated with GBPs irrespective of sarcopenia and visceral obesity.

Interactions among age, adiposity, bodyweight, lifestyle factors and sex steroid hormones in healthy Singaporean Chinese men

Aim： To examine the inter-relationships among age, lifestyle factors, anthropometric parameters, percent body fat and steroid hormone parameters in 531 healthy Singaporean Chinese men aged between 29 and 72 years old. Methods： Various lifestyle parameters were quantified through a survey, and testosterone （T）, estradiol （E2）, dehydroepiandrosterone sulphate （DHEAS） and sex hormone binding globulin （SHBG） were measured using established methods. Anthropometric parameters were collected and computed, and percent body fat （Siri） was measured using the DEXA scanner. Results： SHBG, DHEAS, bioavailable-T （Bio-T）, E2, Siri, Ht, W/H, W/Ht and work stress were independently correlated with age. Using multivariate analyses and adjusting for age and other related factors, exercise, smoking and alcohol consumption have positive impacts on androgen levels and body composition. However, black and green tea consumption was associated with negative effects on body composition and with higher levels of E2 and Free Estradiol Index （FEI）. Men with shorter sleep duration had significantly lower T levels as compared to those with 6 h or more of nightly sleep. Higher T levels were associated with lower levels of adiposity and other indices of adiposity, whereas higher E2 levels were related to higher levels of adiposity. Men with higher DHEAS were significantly taller and heavier than those with low DHEAS levels. Conclusion： The study showed the close interactions among the gonadal/adrenal and metabolic compartments, with age being a key determinant in their interactions. Lifestyle factors such as exercise, smoking, sleeping and alcohol and tea consumption might play significantly roles in determining the status of health in men.

Comparative effects of plant oils and trans-fat on blood lipid profiles and ischemic stroke in rats

Since plant oils are believed to be better than animal fats for cerebrovascular and cardiovascular diseases, the effects of various plant oils and trans-fat on blood lipid profiles and ischemic stroke were investigated. Sprague- Dawley rats were fed a diet containing the oils or trans-fat, and then body weights, blood lipids, and effects on brain infarction and physical dysfunction induced by middle cerebral artery occlusion （MCAO） were analyzed. All the oils and trans-fat, except perilla oil, significantly increased body fats and body weight gain. Sesame oil and trans-fat specifically increased blood cholesterols and triglycerides, respectively, while perilla oil decreased both cholesterols and triglycerides. Perilla oil not only attenuated cerebral infarction, but also restored locomotor activity and rota-rod performances of MCAO rats. It is suggested that perilla oil among oils and fats could be the first choice to reduce the risk of metabolic syndrome and ischemic stroke.

Changes in body composition of women at different age decades and its relation with to metabolic risks

Objective: Aim of this study was to investigate the changes in body composition and some biochemical parameters of women at different age and body mass index (BMI) groups and to evaluate their relations with to cardiometabolic risk factors. Methods: The study was created by retrospective research of the file records of total 800 women who got into nutritional counseling between 2002 - 2007 years at Cerrahpasa Medical Faculty. Participants were grouped as 10 - 19, 20 - 29, 30 - 39, 40 - 49, 50 - 59, ≥60 years according to ages and were divided into 4 groups as normal, overweight, obese and morbidly obese according to body mass index. Data were statistically analysed in SPSS for Windows computer program with ANOVA and Tukey HSD tests. Findings: There are significant differences between different age groups in weight, BMI, waist and hip circumferences, percentage of body water, fat and fat-free mass, basal metabolic rate and blood glucose, insulin, triglyceride, cholesterol, HDL, LDL levels and HOMA-IR values. HOMA-IR values were the highest at age group 1 and the lowest at age group 2. Although they were in the same BMI group;their waist circumference, basal metabolic rate and percent of body fat showed significant increases with advancing age. Conclusion: The findings of our study show that it will be useful to use standard values generated for each age group according to BMI levels in predicting increased cardiovascular and metabolic risks together with advancing age. While the lowest rate of obesity according to body fat percent (>30%) was found at the ages in between 20 - 29 (58.4%), it is noteworthy that the obesity rate with respect to their body fat percent has been noticed at the ages of 10 to 19 (2.3%). Comparing with the other groups, significantly higher body heights found at the ages in between 10 - 19, could possibly predicate that the new generations are having better nutrition and overhaul. On the other hand, it was known that as a result of eating bugs and/or over-nutrition, besides insertion of inactive life style, children have become more sensitive to obesity and related health problems. As seen in our study, the healthiest values are at the ages in between 20 - 29, the results were commentated as the women at those ages are showing more interest in their physical appearance and their health. In accordance with our study’s data, in order to cope with obesity and related illnesses, which are having an importance in public health, we concluded that generalizing continuous and effective trainings on nutrition concerning families even the educators starting from the childhood, can be usefull.

Overweight and abdominal fat are associated with normal bone mineral density in patients with ulcerative colitis

BACKGROUND Low bone mineral density(BMD)is common in patients with inflammatory bowel disease.However,nutritional risk factors for low BMD in the ulcerative colitis(UC)population are still poorly understood.AIM To investigate the association of anthropometric indicators and body composition with BMD in patients with UC.METHODS This is a cross-sectional study on adult UC patients of both genders who were followed on an outpatient basis.A control group consisting of healthy volunteers,family members,and close people was also included.The nutritional indicators evaluated were body mass index(BMI),total body mass(TBM),waist circumference(WC),body fat in kg(BFkg),body fat in percentage(BF%),trunk BF(TBF),and also lean mass.Body composition and BMD assessments were performed by dual-energy X-ray absorptiometry.RESULTS The sociodemographic characteristics of patients with UC(n=68)were similar to those of healthy volunteers(n=66)(P>0.05).Most patients(97.0%)were in remission of the disease,58.8%were eutrophic,33.8%were overweight,39.0%had high WC,and 67.6%had excess BF%.However,mean BMI,WC,BFkg,and TBF of UC patients were lower when compared to those of the control group(P<0.05).Reduced BMD was present in 41.2%of patients with UC(38.2%with osteopenia and 2.9%with osteoporosis)and 3.0%in the control group(P<0.001).UC patients with low BMD had lower BMI,TBM,and BFkg values than those with normal BMD(P<0.05).Male patients were more likely to have low BMD(prevalence ratio[PR]=1.86;95%confidence interval[CI]:1.07-3.26).Those with excess weight(PR=0.43;95%CI:0.19-0.97)and high WC(PR=0.44;95%CI:0.21-0.94)were less likely to have low BMD.CONCLUSION Patients with UC in remission have a high prevalence of metabolic bone diseases.Body fat appears to protect against the development of low BMD in these patients.

Overweight and obesity in young adults with patellofemoral pain:Impact on functional capacity and strength

Purpose:This study aimed to(a)investigate the proportion of overweight/obesity in a cohort of young adults with patellofemoral pain(PFP)and(b)explore the association of body mass index(BMI),body fat,and lean mass with functional capacity and hip and knee strength in people with PFP.Methods:We included a mixed-sex sample of young adults(18-35 years old)with PFP(n=100).Measurements for BMI,percentage of body fat,and lean mass(assessed by bioelectrical impedance)were obtained.Functional capacity was assessed by the Anterior Knee Pain Scale,plank test,and single-leg hop test.Strength of the knee extensors,knee flexors,and hip abductors was evaluated isometrically using an isokinetic dynamometer.The proportion of overweight/obesity was calculated based on BMI.The association between BMI,body fat,and lean mass and functional capacity and strength was investigated using partial correlations,followed by hierarchical regression analysis,adjusted for covariates(sex,bilateral pain,and current pain level).Results:A total of 38%of our cohort had their BMI categorized as overweight/obese.Higher BMI was associated with poor functional capacity(ΔR^(2)=0.06-0.12,p<0.001)and with knee flexion strength only(ΔR^(2)=0.04,p=0.030).Higher body fat was associated with poor functional capacity(ΔR^(2)=0.05-0.15,p≤0.015)and reduced strength(ΔR^(2)=0.15-0.23,p<0.001).Lower lean mass was associated with poor functional capacity(ΔR^(2)=0.04-0.13,p≤0.032)and reduced strength(ΔR^(2)=0.29-0.31,p<0.001).Conclusion:BMI,body fat,and lean mass should be considered in the assessment and management of young people with PFP because it may be detrimental to function and strength.

Steroid hormone 20-hydroxyecdysone disturbs fat body lipid metabolism and negatively regulates gluconeogenesis in Hyphantria cunea larvae

The steroid hormone 20-hydroxyecdysone(20E)has been described to regulate fat body lipid metabolism in insects,but its accurate regulatory mechanism,especially the crosstalk between 20E-induced lipid metabolism and gluconeogenesis remains largely unclear.Here,we specially investigated the effect of 20E on lipid metabolism and gluconeogenesis in the fat body of Hyphantria cunea larvae,a notorious pest in forestry.Lipidomics analysis showed that a total of 1907 lipid species were identified in the fat body of H.cunea larvae assigned to 6 groups and 48 lipid classes.The differentially abundant lipids analysis showed a significant difference between 20E-treated and control samples,indicating that 20E caused a remarkable alteration of lipidomics profiles in the fat body of H.cunea larvae.Further studies demonstrated that 20E accelerated fatty acidβ-oxidation,inhibited lipid synthesis,and promoted lipolysis.Meanwhile,the activities of pyruvate carboxylase,phosphoenolpyruvate carboxykinase,fructose-1,6-bisphosphatase,and glucose-6-phosphatase were dramatically suppressed by 20E in the fat body of H.cunea larvae.As well,the transcriptions of genes encoding these 4 rate-limiting gluconeogenic enzymes were significantly downregulated in the fat body of H.cunea larvae after treatment with 20E.Taken together,our results revealed that 20E disturbed fat body lipid homeostasis,accelerated fatty acidβ-oxidation and promoted lipolysis,but negatively regulated gluconeogenesis in H.cunea larvae.The findings might provide a new insight into hormonal regulation of glucose and lipid metabolism in insect fat body.

Sequence of fat partitioning and its relationship with whole body insulin resistance

Background Currently it is unclear whether lipid accumulation occurs in a particular sequence and its relationship with whole body insulin resistance （IR）. This study aimed to answer this question.Methods Male Sprague-Dawley （SD） rats were fed on a normal or a high-fat diet for 20 weeks. Serum triglycerides （TG）, serum free fatty acids （FFA）, fasting plasma glucose （FPG）, and liver and skeletal muscle TG were measured. The glucose infusion rate （GIR） and mRNA levels of acetyl-CoA carboxylase （ACC） and carnitine palmitoyltransferase-1 （CPT-1） in the liver and skeletal muscle were determined at different stages.Results Compared with rats fed on the normal diet, serum FFA was not significantly increased in rats fed on the high-fat diet until 20 weeks. In contrast, liver TG was significantly increased by the high-fat diet by four weeks （20-fold; P ＜0.01）,and remained elevated until the end of the study. However, skeletal muscle TG was not significantly increased by the high-fat diet until 20 weeks （10.6-fold; P＜0.01）, and neither was the FPG. The GIR was significantly reduced （1.6-fold; P ＜0.01） by the high-fat diet after 8 weeks. The mRNA levels of ACC gradually increased over time and CPT-1 decreased over time, in both the liver and skeletal muscle in rats fed the high-fat diet.Conclusions Lipid accumulation in the liver occurs earlier than lipid accumulation in the skeletal muscle. Fatty liver may be one of the early markers of whole body IR. Changes in the gene expression levels of ACC and CPT-1 may have important roles in the process of IR development.

An Assessment of Predisposing Factors of Atherogenic Dyslipidemia in an Urban Pediatric Population in Cameroon

Background: Dyslipidemia in childhood contributes to an increased risk of cardiovascular diseases later in life. This study sets out to determine the prevalence of dyslipidemia and describe the associations between selected variables and dyslipidemia in Cameroon urban children. Methods: This cross-sectional hospital-based study included 415 children (188 boys and 227 girls) between the ages of 5 and 16 years. Dyslipidemia was defined as an abnormal value of one or more of the following lipids: Total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C). Percentage body fat (%BF) was estimated using bio-electric impedance analysis. A structured questionnaire was used by parents to report physical activity, screen time and eating habits of the children. Relationships between predictors and dyslipidemia were assessed using multiple binary logistic regression analyses. Results: The prevalence of dyslipidemia was 46.0%. Dyslipidemic children had significantly higher %BF, TG and LDL-C and lower HDL-C than the normal children (p p = 0.004), short stature (OR 2.8, 95% CI 1.1 - 6.8, p = 0.041), physical activity p Conclusion: This study confirms that obesity, short stature, physical activity < 60 minutes/day and never/occasional consumption of fruits/vegetables were associated with dyslipidemia. Also, a high proportion of children had one or more lipid disorders. This is concerning and indicates the importance of assessing dyslipidemia in pre-school children in future studies.

The piRNA response to BmNPV infection in the silkworm fat body and midgut

Bombyx mori nucleopolyhedrovirus(BmNPV)is a DNA virus that causes huge losses to the silkworm industry but the piRNA responses during BmNPV infection in the silkworm remain uninvestigated.Here,silkworm piRNA profiles of uninfected and BmNPV-infected fat body and midgut were determined by high-through sequencing in the early stages of BmNPV infection.A total of 2675 and 3396 genome-derived piRNAs were identified from fat body and midgut,respectively.These genome-derived piRNAs mainly originated from unannotated instead of transposon regions in the silkworm genome.In total,572 piRNAs were associated with 280 putative target genes in fat body and 805 piRNAs with 380 target genes in midgut.Compared to uninfected tissues,322 and 129 piRNAs were significantly upregulated in BmNPV-infected fat body and midgut,respectively.In addition,276 and 117 piRNAs were significantly downregulated.Moreover,differentially expressed(DE)piRNAs during BmNPV infection differed significantly between fat body and midgut.Putative DE piRNA-targeted genes were associated with“response to stimulus”and“environmental information processing”in fat body after infection with BmNPV,which may indicate an active piRNA response to BmNPV infection in fat body.This study may lay the foundation for future research of the potential roles of the piRNA pathway and specific piRNAs in BmNPV pathogenesis.

Two dehydroecdysone reductases act as fat body-specific 20E catalyzers in Bombyx mori

Periodic post-embryonic changes in insects, including growth, development and metamorphosis, are strictly controlled by many compounds, including steroid hormones. The biosynthesis and clearance of 20-hydroxyecdysone (20E), the major active form of the insect steroid hormone ecdysone, result in titer fluctuations that help control insect development. The inactivation of 20E in the silkworm Bombyx mori is highly tissue-specific, with CYP18A1 and ecdysone oxidase controlling 20E inactivation specifically in the mid-silk gland and midgut, respectively. Here, we characterized silkworm 3-dehydroecdysone 3α reductase (Bm3DE3α) and 3-dehydroecdysone 3β reductase (Bm3DE3β), two enzymes involved predominantly in the C-3-mediated catalysis of 20E in fat bodies. The ubiquitous and silk gland-specific overexpression of Bm3DE3α decreased the 20E titer, resulting in larval lethality and larval–pupal transition failure, respectively. In contrast, the ubiquitous and mid-silk gland-specific overexpression of Bm3DE3β increased the 20E titer, resulting in larval growth delays and lethality at the mid-fifth larval stage, respectively. Thus, Bm3DE3α and Bm3DE3β mediate fat body-specific steroid hormone metabolism in B. mori, indicating that highly diversified 20E metabolism-related mechanisms exist in different insect species.

Differences in nutrient uptake between the fat body and embryonic primary cultures of silkworm （Bombyx mori）

Nutrition utilization and by-product formation in cultured insect cells has been investigated in several insect cells and has been of great interest to cell culturists and physiologists. In this research the biochemical changes in embryonic and fat body primary cultures of silkworm, Bombyx mori, have been compared. TC-100 medium supplemented with 10% and 20% FBS was used in embryonic and fat body primary cultures, respectively. Medium was renewed every week and the amount of glucose, uric acid, urea, total protein and alkaline phosphatase were measured in the samples from medium of primary cultures using spectrophotometeric methods. All biochemical macromolecules except uric acid showed significant changes. Glucose decreased in embryonic tissues, while in fat body culture its amount increased. Urea accumulation in embryonic culture was higher than in the fat body cultures. Since urea is a by-product, this accumulation could be due to higher utilization of amino acids. Total protein showed considerable changes and was consumed by embryonic culture more than the fat body＇ s. Alkaline phosphatase showed stronger activity in embryonic cells.