Low-density lipoprotein receptor-related protein 2(LRP2)is required for lipid export in the midgut of the migratory locust,Locusta migratoria

Low-density lipoprotein receptor-related protein 2(LRP2)is a multifunctional endocytic receptor expressed in epithelial cells.In mammals,it acts as an endocytic receptor that mediates the cellular uptake of cholesterol-containing apolipoproteins to maintain lipid homeostasis.However,little is known about the role of LRP2 in lipid homeostasis in insects.In the present study,we investigated the function of LRP2 in the migratory locust Locusta migratoria(LmLRP2).The mRNA of LmLRP2 is widely distributed in various tissues,including integument,wing pads,foregut,midgut,hindgut,Malpighian tubules and fat body,and the amounts of LmLRP2 transcripts decreased gradually in the early stages and then increased in the late stages before ecdysis during the nymphal developmental stage.Fluorescence immunohistochemistry revealed that the LmLRP2 protein is mainly located in cellular membranes of the midgut and hindgut.Using RNAi to silence LmLRP2 caused molting defects in nymphs(more than 60%),and the neutral lipid was found to accumulate in the midgut and surface of the integument,but not in the fat body,of dsLmLRP2-treated nymphs.The results of a lipidomics analysis showed that the main components of lipids(diglyceride and triglyceride)were significantly increased in the midgut,but decreased in the fat body and hemolymph.Furthermore,the content of total triglyceride was significantly increased in the midgut,but markedly decreased in the fat body and hemolymph in dsLmLRP2-injected nymphs.Our results indicate that LmLRP2 is located in the cellular membranes of midgut cells,and is required for lipid export from the midgut to the hemolymphand fat body in locusts.

Azole selenourea disrupted the midgut and caused malformed development of Plutella xylostella

Chemical insecticides targeting the digestive system of diamondback moth(DBM),Plutella xylostella,have not been developed.The discovery of an insecticide with novel mode of action is a challenge for the control of DBM.In this study,a class of selenium-and difluoromethyl-modified azoles(fluoroazole selenoureas,FASU)were designed and synthesized for the control of DBM.Of these azoles,compound B4 showed the highest insecticidal activity against DBM.The LC50of third-and second-instar larvae reached 32.3 and 4.6μg mL^(–1),respectively.The midgut tissue of larvae was severely disrupted,and the larval intestinal tissue was dotted with unique red spots after treatment with compound B4.Compound B4 led to disintegration of the peritrophic matrix,swelling of the midgut epithelium,fracture of the microvilli,and extensive leakage of cellular debris in the midgut lumen.Surviving larvae grew very slowly,and the larval duration was significantly prolonged after exposure to compound B4 at sublethal doses(LC10,LC25and LC50).Furthermore,the pupation rate,emergence rate and pupae weight were significantly decreased.Compound B4 also induced abnormal pupae,causing adults to be trapped in the cocoon or failure to fly due to twisted wings.These results demonstrated that FASU could reduce the population of DBM in sublethal doses.FASU is the first synthetic insecticidal lead compound that has been shown to disrupt the midgut tissue of the larvae of DBM,and its mode of action totally differs from that of commercial chemical insecticides.

Construction of Midgut Tissue-Specific cDNA Library of Bombyx mandarina M. and Isolation and Sequence Analysis of Serine Protease Gene Fragment

[Objective] The aim of the study is to construct cDNA library of midgut tissue of wild silkworm and isolate the serine protease gene. [Method] The midgut tissue-specific cDNA library of wild silkworm was constructed via cDNA Library Construction Kit (TaKaRa), then the serine protease gene was cloned via sequencing of the yielded cDNA library. [Result] The titer of cDNA library reached 6.2×105 pfu/ml, average insert size was about 1.2 kb. The serine protease gene cDNA fragment was obtained from colony sequencing (Accession No: EU672968). The nucleotide sequence of the cloned 854 bp fragment encodes 284 amino acid residues. Homology analyses showed some homology between putative amino acid sequence of the cloned fragment and amino acid sequences of serine proteases from other ten insects. [Conclusion] The results may avail to reveal the resistance of silkworm and wild silkworm to exotic intrusion.

Histopathological Effects of the Protein Toxin from Xenorhabdus nematophila on the Midgut of Helicoverpa armigera

Xenorhabdus nematophila HB310, which is highly virulent for many insects, is symbiotic with Steinernema carpocapsae HB310. Toxin II was obtained using methods such as salting out and native-PAGE from the cells of X. nematophila HB310. The histopathology of toxin II on H. armigera larvae was studied by dissecting an olefin slice of the midgut. The symptoms showed that the histopathology of the H. armigera midgut was similar to that of other novel midgut-active toxins such as the δ-endotoxins from Bacillus thuringiensis, as well as Tca from Photorhabdus luminescens W14. The midgut tissues of H. armigera fourth-instar larvae began to transform after the oral intake of the toxin Ⅱ over 6 h. First, the anterior region of the peritrophic membrane （PM） began to degrade followed by the elongation of the columnar cells. The epithelium decomposed gradually, and the midgut tissues were either loose or disordered. The PM disappeared after 12 h but reappeared after 72 h following transient or sublethal exposure to the toxin Ⅱ. Toxin Ⅱ also directly destroyed in vitro PMs of H. armigera.

Intrauterine midgut volvulus without malrotation:Diagnosis from the 'coffee bean sign'

Fetal midgut volvulus is quite rare, and most cases are associated with abnormalities of intestinal rotation or fixation. We report a case of midgut volvulus without malrotation, associated with a meconium pellet, during the gestation period. This 2.79 kg, 33-wk infant was born via a spontaneous vaginal delivery caused by preterm labor. Prenatal ultrasound showed dilated bowel loops with the appearance of a 'coffee bean sign'. This patient had an unusual presentation with a distended abdomen showing skin discoloration. An emergency laparotomy revealed a midgut volvulus and a twisted small bowel, caused by complicated meconium ileus. Such nonspecific prenatal radiological signs and a low index of suspicion of a volvulus during gestation might delay appropriate surgical management and result in ischemic necrosis of the bowel. Preterm labor, specific prenatal sonographic findings (for example, the coffee bean sign) and bluish discoloration of the abdominal wall could suggest intrauterine midgut volvulus requiring prompt surgical intervention.

A Study on the Activity of Carboxylesterase and the Differential Expression of Its Gene in the Midguts of Bombyx mori Resistant to BmDNV-Z

This study was to discuss the relationship among the change in the activity of Bombyx mori carboxylesterase （BmCarE） in the midguts, the differential expression of BmCarE gene （bmcare） in the midguts, and the ability of Bombyx mori resistant to densonucleosis virus （BmDNV）, and to elucidate the molecular mechanism of resistance to BmDNV-Z. With two silkworm strains, HUABA, which is susceptible to BmDNV-Z, and BC8 （a near isogenic line of HUABA）, which is completely resistant to the same virus, as materials, the activity of BmCarE in the midgut was determined by Bio-Tek Synergy, and the differential expression of bmcare between the two strains was investigated by real-time fluorescence quantitative PCR, both at 12, 36, and 72 h post oral inoculation of the two strains with virus （hereafter referred as inoculation）. While the activity of BmCarE in the midguts of BC8 inoculation group at 12 h post inoculation was higher than that in the BC8 control group, the HUABA inoculated group, and the HUABA control group by 3.28, 2.26, and 3.02 times, respectively, with the difference being highly significant （P 〈 0.01）, there was no statistical difference among the other groups. The relative expression level of bmcare in the midguts of BC8 inoculation group at 12 h post inoculation was higher than that in the BC8 control group, the HUABA inoculation group, and the HUABA control group by 17.714, 21.76, and 15.09 times, respectively, with the difference being highly significant （P 〈 0.01）, and there was no statistical difference among other groups. The elevation of BmCarE activity and expression level of bmcare in the resistant strain at 12 h post inoculation may relate to the resistant gene （nsd/nsd） and the stimulation of BmDNV-Z. The molecular basis for the elevation of BmCarE activity in the resistant strain BC8 may be the change in the expression level of bmcare.

Midgut volvulus due to jejunal diverticula:A case report

Jejunal diverticulosis is uncommon and often asymptomatic.It can produce significant complications,and some complications are potentially life threatening and require early surgical treatment,such as obstruction,hemorrhage and perforation.There is no consensus on the management of this disease.Only a few cases of jejunal diverticulosis with midgut volvulus have been reported.We herein report a case of 57-year-old woman with jejunal diverticulosis causing small bowel volvulus who complained of intermittent upper abdominal pin-prick for 5 years that eventually progressed to a complete obstruction.The computed tomography scans revealed a mesenteric vessel "whirlpool" and laparotomy showed midgut volvulus secondary to jejunal diverticula.This case highlights jejunal diverticulosis causing small bowel volvulus as an uncommon mechanism of small bowel obstruction,which should be included in the differential diagnosis of small bowel obstruction.

Effects of inhibitors on the protease profiles and degradation of activated Cry toxins in larval midgut juices of Cnaphalocrocis medinalis (Lepidoptera:Pyralidae)

Midgut juice plays an important role in food digestion and detoxification in insects.In order to understand the potential of midgut juice of Cnaphalocrocis medinalis(Guenée)to degrade Bt proteins,the enzymatic activity of midgut juice and its degradation of Bt proteins(Cry2A,Cry1C,Cry1Aa,and Cry1Ac)were evaluated in this study through protease inhibitor treatments.The activities of total protease in midgut juices were significantly inhibited by phenylmethylsulfonyl fluoride(PMSF),tosyl-L-lysine chloromethyl ketone(TLCK),pepstatin A and leupeptin.The enzymatic activity of chymotrypsin was significantly inhibited by PMSF,and enzymatic activity of trypsin was significantly inhibited by ethylenediaminetetraacetic acid(EDTA),PMSF,tosyl phenylalanine chloromethyl ketone(TPCK),TLCK and trans-epoxysuccinyl-L-leucylamido-(4-guanidino)butane(E-64).EDTA could significantly inhibit the degradation of Cry2A by C.medinalis.EDTA,PMSF,TPCK,and TLCK could inhibit the degradation of Cry1C and Cry1Aa.EDTA,PMSF,TPCK,TLCK,and E-64 could inhibit the degradation of Cry1Ac.Our results indicated that some protease inhibitors hindered various enzymatic activities in the larval midgut of C.medinalis,which may reduce the insect’s ability to degrade Bt toxins.These findings may aid the application of protease inhibitors in the management of this insect pest in the future.

Intestinal obstruction in pregnancy with reverse rotation of the midgut:A case report

BACKGROUND Reverse rotation of the midgut is a rare type of intestinal malrotation.Volvulus of the right colon or entire midgut,stenosis of the transverse colon and obstruction of the duodenojejunal junction are common complications of reverse rotation.In this study,we report the first case of intestinal obstruction associated with reverse rotation in pregnancy.CASE SUMMARY A 31-year-old woman at 362+wk gestation presented to the emergency department with progressive abdominal cramping,nausea and bilious vomiting.Abdominal ultrasound scanning showed dilatation of the bowel.Computed tomography scanning revealed features of reverse rotation of the midgut with intestinal volvulus.After consultation with the obstetrician,the pregnancy was terminated and exploratory abdominal surgery was performed.Intra-operatively,it was found that the mesentery of the colon and small intestine was insufficiently attached.The right colon and the small intestinal mesentery was twisted,and intestinal necrosis was observed.The duodenum and duodenojejunal junction were curved in front of the transverse colon,and the transverse colon passed through the tunnel behind the mesenteric root.Intestinal reverse rotation with volvulus was confirmed.The necrotic intestine was resected and small intestine mesenteric reconstruction was performed.The patient recovered after surgery.After leaving the hospital,the patient and her daughter remained well during an 8-month follow-up period.CONCLUSION We report the diagnosis,treatment and etiology of a pregnant patient with intestinal obstruction due to reverse rotation of the midgut.For similar cases,appropriate diagnosis and treatment should be carried out according to the condition of the fetus and pregnant woman.

The Midgut Bacterial Flora of Laboratory-Reared Hard Ticks, Haemaphysalis longicornis, Hyalomma asiaticum, and Rhipicephalus haemaphysaloides

Ixodid ticks play an important role in the transmission of a variety of zoonoses of viral, bacterial and protozoan origin, and they also harbor a wealth of microorganisms. To gain more detailed insights into the potential interactions between bacterial flora and tick-borne pathogens, we investigated the midgut bacterial flora of laboratory-reared Haemaphysalis longicornis, Hyalomma asiaticum and Rhipicephalus haemaphysaloides. Based on morphological, biochemical, and 16 S rDNA sequencing results, we identified 15 species belonging to 12 genera in the midgut of the three ticks. The bacterial communities were similar to those found in other studies of hematophagous arthropods. Kocuria sp. was the most frequently isolated species and its 16 S rDNA gene sequence was very similar to Kocuria koreensis P31 T. To our knowledge, this is the first report of the bacterial flora of tick midguts and the results show that there were many different bacterial species in each tick species. Among the most common genera, there may have been a novel species in the genus Kocuria. The results might be the first step for looking for different aspects of the pathogen and tick interaction.

Use of Ultrastructuke and DNA Hybridization to Detect Replication of the Nuclear Polyhedrosis Virus in Midgut Cells of Homologous Host

It was controversial issue if nuclear polyhedrosis virus(NPV) could replicate in midgut cells of host larvae from Lepidoptera by now.The replication of Mythimna separata NPV(MsNPV) in M.separata larvae midgut cells was studied by ultrastructural and DNA hybridized techniques.The paper demonstrated that the MsNPV could neither infect midgut cell nor replicate in midgut cell of homologous host.Therefore MsNPV virions released from the virial occlusion bodies were considered as direct penetration though the intercellular spaces of midgut cells to hemocoel of the host larvae.

Effect of Zinc Sulfate against the Red Palm Weevil Rhynchophorus ferrugineus with Reference to Their Histological Changes on the Larval Midgut and Adult Reproductive System

The red palm weevil Rhynchophorusferrugineus is the most important insect pest for the date palm trees in the Middle East and Gulf states. Zinc sulfate （ZnSOa＇H20） was toxicologically, biologically and physiologically evaluated as insect development disruptors against the RPW. LCs0 of Zinc sulfate against 10 days old larvae was 0.566%, 3% concentration inhibited the larvae from feeding. LCs0 concentration of zinc sulfate solution was capable to disrupting growth, development and reproduction of R. ferrugineus. Growth and development disruptions are resulted from larval feeding on the treated diet that causing percentage of mortality rate, retardation in larval and pupal duration, percentage of pupation, adults emergence, reduction in deposited eggs that laid by the resulting adults and in the egg fertility. The study further reveals that Zinc sulfate effects on histological structure of epithelial cells of the larval midgut including separation and elongation of their cells, rupture in the peritrophic membrane and in some microvilli and some degeneration of the surrounding muscles. Histological changes also was observed on the adults ovary, in this way, disrupt female gamete production through their action on the accumulation of yolk granules （vitellogenesis） and follicular epithelial cells. Disruption of male gamete production was detected by disorganized of testicular cysts and depopulation of these cysts in addition to degeneration in germ cells. Zinc sulfate may be used among other control methods by injection into the tree trunk or as fertilizer around the tree roots which in turn may have an indirect effect for controlling the RPW.

A Case Report of Adult Patent Vitellointestinal Duct Sac and Midgut Volvulus

Midgut volvulus is a clinical rare condition which appears as recurrent intermittent abdominal pain after consumption of food with intermittent colicky pain and sometimes with completely asymptomatic period. This gut twist may result in complications such as ischemia, obstruction, hemorrhage, or perforation. In the yolk sac during the third week of intrauterine life, there is normal communication with intraembryonic gut. During development proceeds, this communication gets thinner into a tube known as the vitellointestinal duct. Vitellointestinal duct usually becomes obliterated before eighth week of intrauterine life. In about 2% of people this duct persists and gives rise to a group of anomalies such as Meckel’s diverticulum is the commonest and complete patency of the duct is the rarest. Here we present the case of a 34-year-old male who presented with both conditions.

成人中肠旋转不良的CT诊断和鉴别诊断

目的通过回顾分析15例成人中肠旋转不良病人的CT影像资料,以期能提高放射科医生对该病的正确认识、减少误诊。方法回顾性分析15例成人中肠旋转不良病人的CT影像资料,并归纳总结其CT影像特点及鉴别诊断。结果15例患者中11例出现“漩涡征”,9例出现肠系膜动静脉血管“换位征”,4例出现回盲部异位,1例出现十二指肠异位,1例出现横结肠异位;其中1例合并异位阑尾炎,1例合并小肠梗阻,1例合并胆总管轻度低位梗阻改变。结论成人中肠旋转不良患者的CT表现可能有一些较特异的征像,如“漩涡征”和肠系膜血管“换位征”等,但还需密切结合临床仔细分析,鉴别其他疾病,以提高其影像诊断的准确率、减少误诊。

家蚕蛹变态期的中肠发育变化观察及细胞凋亡与自噬相关基因的表达检测

为探究家蚕中肠在蛹变态过程中的形态发育变化,于家蚕5龄幼虫期、蛹期及蛾期以24h为间隔,对其中肠进行解剖观察,结果显示:家蚕5龄幼虫的中肠为长圆筒形,在食桑期呈绿色、膨大的管状,进入熟蚕期停止食桑后,中肠开始变黄、缩短;在熟蚕营茧化蛹的过程中,中肠持续缩短、变小,并随着发育时期的延长,最终呈椭圆形颗粒状,表面颜色由浅黄色变为棕黄色。进一步观察家蚕不同发育时期中肠组织的石蜡切片,发现幼虫中肠细胞在进入蛹变态期发生了多次凋亡与再生的过程,在上蔟3~4d、上蔟7~8d、上蔟12d~蛾期都形成了新的中肠上皮细胞,这些新的中肠上皮细胞可能是由再生细胞分化更新而来的。对家蚕中肠组织中细胞凋亡基因(Caspase-1、BmDredd)与自噬基因(Atg1、Atg13)表达模式的检测结果显示,Caspase-1、BmDredd在上蔟2d、7d、12d的表达量均降低,Atg1、Atg13在上蔟7d、9d、12d的表达量均降低,表明在家蚕的这些变态发育时期,其中肠细胞的凋亡受到了抑制,与切片观察新的中肠上皮细胞形成时期基本一致。研究结果呈现了家蚕中肠在蛹变态时期的发育变化过程,说明家蚕幼虫的中肠在蛹发育变态过程中并未彻底消亡,成虫的中肠是幼虫中肠在蛹变态时期经过多次消亡与再生过程发育而来的。

家蚕响应微孢子虫感染的可变剪接事件分析

【目的】家蚕微孢子虫(Nosema bombycis)感染引发的微粒子病是影响蚕业发展的重要病害。为了揭示可变剪接(AS)基因在家蚕响应微孢子虫感染中的作用,对其中肠内的AS事件进行分析。【方法】利用Illumina Hiseq TM 4000测序平台,对健康家蚕(对照组)和被微孢子虫感染的家蚕中肠组织进行转录组测序。使用rMATS软件对样品中的AS事件与差异剪接基因(DSGs)进行鉴定,并对DSGs进行GO富集和KEGG信号通路分析。【结果】在对照组和感染组中分别检测到5346个和4992个AS事件,两组的AS事件类型都以外显子跳跃(SE)事件为主,差异分析发现了25个显著的DSGs。GO富集分析表明,DSGs主要富集在21个条目,其中以细胞过程、物质代谢、结合、催化活性的基因数量较多;KEGG信号通路分析显示,DSGs富集数较多的是信号传导、免疫系统、多糖生物合成与降解、能量代谢等通路。【结论】家蚕中肠组织存在大量AS事件,在微孢子虫感染过程中存在25个DSGs,其功能涉及新陈代谢和细胞免疫等。

取食四种寄主植物对番茄潜叶蛾中肠肠道细菌的影响

番茄潜叶蛾Tuta absoluta是一种世界性害虫,寄主范围广泛,对多种寄主作物造成严重危害。通过16S rRNA测序分析了取食番茄、马铃薯、茄子、和人参果的番茄潜叶蛾2龄幼虫中肠肠道细菌的多样性和功能。结果显示,在上述四种寄主植物为食的番茄潜叶蛾中肠肠道细菌中,共检测到4886、6016、2781、3471个操作分类单元(OTU),其中共有905个OUT。Alpha和Beta多样性分析结果表明,取食马铃薯和茄子的番茄潜叶蛾中肠肠道细菌多样性最高。物种分类分析表明,取食不同寄主的番茄潜叶蛾,中肠肠道细菌在门水平的优势菌群均为厚壁菌门和变形菌门;在属水平上,取食番茄和马铃薯的番茄潜叶蛾中肠肠道细菌优势属为沃尔巴克氏体,取食人参果和茄子的为肠球菌属;对其代谢通路分析,发现取食四种寄主植物其中肠肠道细菌代谢通路相似,无显著差异,且占比最高的代谢通路都为生物合成和降解代谢。

刻点血蜱成蜱中肠菌群结构的分析

旨在探明雌、雄刻点血蜱中肠菌群结构特征及其差异。从新疆沙湾市绵羊体表采集刻点血蜱雌、雄蜱,无菌条件下收集雌、雄蜱中肠内容物,提取各样本细菌总DNA,PCR扩增细菌16S rDNA V3-V4区,运用Illiumina NovaSeq高通量双末端测序,对数据进行拼接和过滤,扩增子序列变异(ASVs)降噪与物种注释后,对比分析雌、雄蜱中肠菌群结构的组成及差异。结果:雌蜱中肠菌群多样性高于雄蜱;在门水平上,变形菌门、厚壁菌门、异常球菌门、拟杆菌门、放线菌门在雌、雄蜱中肠内相对丰度较高,其中变形菌门相对丰度最高,为2个样本的优势菌门,且变形菌门在雄蜱中肠内的含量大于雌蜱;在属水平上,Schlegelella、不动杆菌属、拟杆菌属、乳杆菌属、短波单胞菌属、罗姆布茨菌属等在雌、雄蜱中肠内的相对丰度较高,其中Schlegelella的丰度最高,且在雌蜱(41.7%)中的含量高于雄蜱(0.8%);注释到种水平且2个样本共有的菌种包括:西尔瓦诺斯亚栖热菌、鲍曼不动杆菌、柯克斯氏体共生菌、肠乳杆菌、长双歧杆菌、巴氏杆菌拟杆菌等。本研究表明,刻点血蜱雌、雄蜱中肠菌群结构较为相似,但各细菌在不同分类级别上的相对丰度差异较大,这可能与雌、雄蜱吸血及生理特性不同有关。

A midgut-specific serine protease, BmSP36, is involved in dietary protein digestion in the silkworm, Bombyx mori

Serine proteases play important roles in digestion and immune responses during insect development. In the present study, the serine protease gene BmSP36, which encodes a 292-residue protein, was cloned from the midgut cells ofBombyx mori. BmSP36 contains an intact catalytic triad （H57, D102 and S195） and a conserved substrate-binding site （G189, H216 and G226）, suggesting that it is a serine protease with chymotrypsin- like specificity. The temporal and spatial expression patterns of BmSP36 indicated that its messenger RNA and protein expression mainly occurred in the midgut at the feeding stages. Western blotting, immunofluorescence and liquid chromatography-tandem mass spectrometry analyses revealed secretion of BmSP36 protein from epithelial cells into the midgut lumen. The transcriptional and translational expression of BmSP36 was down- regulated after starvation but up-regulated after refeeding. Moreover, expression of the BmSP36 gene could be up-regulated by a juvenile hormone analogue. These results enable us to better define the potential role of BmSP36 in dietary protein digestion at the feeding stages during larval development.

蜱传病原体的危害及其与媒介蜱相互作用的研究进展

蜱作为一大类传播媒介,可传播多种病原体,如嗜吞噬细胞无形体和伯氏疏螺旋体,造成人和动物的无形体病和莱姆病,危害公共卫生安全。然而,化学药物的滥用导致蜱及蜱传病原体产生耐药性,而抗蜱疫苗存在一定的局限性,亟需找到有效且绿色安全的蜱和蜱传病的防控方法。一些病原体在传播过程中逐渐进化出特定机制,如调控蜱细胞凋亡、免疫逃避等促进其在蜱体内的生长发育;而蜱自身也产生了某些应对机制来抵御或协同传播病原体,如分泌外泌体小囊泡协同传播病毒,促进自身受感染细胞凋亡,分泌唾液蛋白调节宿主补体途径,形成肠道屏障等。本文对蜱传病原体的类型和危害、病原体经蜱唾液腺传播的相互作用机制以及蜱中肠屏障和肠道菌群与病原体增殖的相互关系共3个方面进行综述,希望能为后续防控蜱和蜱传病及抗蜱药物的相关研究提供参考。