Drumstick is a zinc finger protein that antagonizes Lines to control patterning and morphogenesis of the Drosophila hindgut

Elongation of the Drosophila embryonic hindgut epithelium occurs by a process of oriented cell rearrangement requiring the genes drumstick (drm) and lines (lin). The elongating hindgut becomes subdivided into domains -- small intestine, large intestine and rectum -- each characterized by a specific pattern of gene expression dependent upon normal drm and lin function. We show that drm encodes an 81 amino acid (10 kDa) zinc finger protein that is a member of the Odd-skipped family. drm expression is localized to the developing midgut-hindgut junction and is required to establish the small intestine, while lin is broadly expressed throughout the gut primordium and represses small intestine fate. lin is epistatic to drm, suggesting a model in which localized expression of drm blocks lin activity, thereby allowing small intestine fate to be established. Further supporting this model, ectopic expression of Drm throughout the hindgut produces a lin phenotype. Biochemical and genetic data indicate that the first conserved zinc finger of Drm is essential for its function. We have thus defined a pathway in which a spatially localized zinc finger protein antagonizes a globally expressed protein, thereby leading to specification of a domain (the small intestine) necessary for oriented cell rearrangement.     

Regulatory interactions and role in cell type specification of the Malpighian tubules by the cut, Krüppel, and caudal genes of Drosophila.

Krüppel and caudal genes are both required for normal segmentation of the embryo, and the developmental regulatory gene cut is necessary for the normal specification of external sensory organs. These three genes are also expressed in the Malpighian tubules before and during differentiation. Two of the genes, Krüppel and cut, are known to be required for development of the tubules. We report that the absence of maternal and zygotic caudal function reduces their normal growth and elongation. Normal Krüppel function, which is known to be required for caudal expression, is also required for cut expression, while cut and caudal are expressed independently of each other. Cell type transformations of Malpighian tubules were studied by examining the effects of mutations on the expression of markers specific to Malpighian tubules, hindgut, or midgut of normal embryos. Loss of Krüppel activity confers hindgut characteristics on those cells that normally form the Malpighian tubules with all markers tested. Loss of cut function alters the expression of some markers but not others. The pathway of tissue specific gene regulation, apparently, branches beyond Krüppel to form at least a cut and a caudal branch.     

Genes controlling posterior gut development in theDrosophila embryo

Our present detailed understanding of the genetic mechanisms controlling segmentation has been made possible, in large part, by comprehensive screens of cuticular morphology that identified genes involved in epidermal patterning. To systematically identify genes involved in internal morphogenesis, specifically development of the gut, we have screened mutant embryos produced by a collection of 53 embryonic lethal mutations affecting embryonic pattern formation or differentiation, and a collection of 161 deficiencies covering, in aggregate, approximately 70% of the genome. Staining with the anti-crumbs antibody was used to characterize the Malpighian tubules and hindgut, as well as other internal organs. The geneshuckebein, tailless andwingless, and two previously undescribed loci at 24C/D and 68D/E, are required to establish the primordia for the posterior midgut and hindgut/Malpighian tubules. A locus in region 30A/C is required for extension of the midgut epithelium to surround the yolk, and region 36E/37F is required for outbudding of the Malpighian tubule primordia. Several deficiencies were identified that uncover loci with specific effects on the morphogenesis (elongation, lumen formation) of the hindgut and Malpighian tubules and on the formation of constrictions in the midgut.     

Expression patterns of genes encoding proteins with peritrophin A domains and protein localization in Mamestra configurata

Genes encoding three proteins (McPPAD1-3) with peritrophin A chitin-binding domains (PADs) were identified from a Mamestra configurata larval midgut cDNA library. In addition to midgut, McPPAD1-3 and a previously identified gene encoding the peritrophin, McPM1, were expressed in foregut, hindgut, Malpighian tubules, tracheae, fat body and cuticle; however, the corresponding McPPAD proteins exhibited different localization patterns. McPPAD1 was restricted to the digestive tract and Malpighian tubules, McPPAD2 to Malpighian tubules, and McPPAD3 to the foregut, midgut, hindgut, tracheae and cuticle. Protein fold recognition analysis using tachycitin as a guide structure modelled the McPPAD1 PADs, but not McPPAD2 or McPPAD3 PADs. The McPPAD1 PADs were predicted to contain three anti-parallel β-sheets and a hevein-like fold that form a chitin-binding pocket containing two hydrophobic R-groups in a sandwich-like orientation.     

Age- and diapause-related acid and alkaline phosphatase activities in the intestine and malpighian tubules of the Colorado potato beetle, Leptinotarsa decemlineata (Say)

Specific activities for soluble (s) and membrane (m)-bound acid (ACP) and alkaline phosphatases (ALP) were determined in the midgut, hindgut, and Malpighian tubules for developing, prediapausing, and diapausing adult Colorado potato beetles, Leptinotarsa decemlineata (Say). High ACP activities were found in the hindgut and Malpighian tubules while high ALP activities were found in the Malpighian tubules. Variation in both ACP and ALP activities in each tissue reflects fluctuation in protein synthesis and secretion involved with digestion, excretion, and other unknown functions. Phosphatase activities in the tissues examined show the dynamic nature of diapause in this insect. Diapausing beetles showed increases in phosphatase activity after hormone treatments. JHA treatments increased s-ACP and m-ACP activities in all tissues but 20-HE did not increase activity in any tissue. Allatotropin tended to mimic the effects of JHA treatment. The s-ALP activity was also increased in all tissues whereas m-ALP was increased in the midgut and hindgut by JHA treatment. Malpighian tubule m-ALP activity was only increased by 20-HE treatments. Allatotropin was not as effective in increasing ALP activities as it was with ACP activities.     

Development of the Malpighian tubules in Cloeon dipterum (Ephemeroptera)

The development of the Malpighian tubules is studied in Cloeon dipterum through all stages from the youngest larva to the adult. The Malpighian tubules are found to be outgrowths of the posterior part of the endodermal midgut and not of the ectodermal hindgut. In the adult the part of the intestine with the tubule openings becomes separated by an ingrowing fold of the epithelium from the anterior main part of the midgut that forms a large thin-walled and air-filled bladder. The characteristics of the developmental stages, which served to determine the age of the animals, are given.     

黄脸油葫芦与短额负蝗马氏管组织结构比较

采用组织学方法对直翅目剑尾亚目和锥尾亚目的两个物种--黄脸油葫芦Teleogryllus emma和短额负蝗Atractomorpha sinensis成虫的马氏管进行了观察,发现两者在着生位置、方式和细胞结构上存在明显不同.着生位置上,黄脸油葫芦的马氏管着生在后肠前端与后肠后端的交界处,短额负蝗的马氏管着生在中肠与后肠的交界处.着生方式上,黄脸油葫芦的马氏管是通过一根无色透明的公共管与肠道相通的,而短额负蝗的马氏管分为12丛,每一丛直接与肠道相连.细胞结构上,黄脸油葫芦的管壁由8个细胞构成,且集中在管的中央,与管壁有空隙;而短额负蝗的管壁由3～4个细胞组成,分散在管壁外围,有马氏管凸.     

黄脸油葫芦消化道和马氏管的组织学观察

应用石蜡切片技术对黄脸油葫芦Teleogryllus emma(Ohmachi and Matsumura)成虫消化道和马氏管的显微结构进行观察。消化道由前肠、中肠和后肠3部分组成:前肠由内向外可分为6层:内膜、肠壁细胞层、底膜、纵肌、环肌和围膜;中肠组织结构也分为6层,即由内向外依次为围食膜、肠壁细胞层、底膜、环肌、纵肌和围膜;后肠的组织结构与前肠基本相似,但内膜比前肠的薄,且肌肉的排列较前肠不规则,与中肠的肌肉排列相似,即环肌在内,纵肌在外。消化道各部位的结构差异与功能有密切关系。马氏管管壁由8个左右形状多变并具有显著细胞核的大形的单层上皮细胞组成。     

Complexity in evolved regulatory variation for alcohol dehydrogenase genes in HawaiianDrosophila

Summary The alcohol dehydrogenase gene (Adh gene) ofDrosophila affinidisjuncta is expressed at a higher level in the larval midgut and Malpighian tubules than the homologous gene fromDrosophila hawaiiensis. This study analyzed thecis-acting sequences responsible for these regulatory differences in larval tissues ofDrosophila melanogaster transformants. A series of 10 chimeric and deletedAdh genes was introduced into the germ line ofD. melanogaster, and tissue-specific expression levels were quantified by gel electrophoresis of tissue extracts. Sequences in the upstream region of the two genes had the strongest influence on enzyme production in the midgut and Malpighian tubules. Other sequence elements also showed effects, some of which were tissue specific. Most gene fragments displayed context-dependent effects, thus supporting the proposed model of polygenic regulation ofAdh gene expression.     

The gut structure of Sinentomon erythanum yin (Protura : Sinentomidae)

The fine structure of the midgut, pyloric region, Malpighian papillae, and hindgut of Sinentomon erythranum (Protura : Sinentomidae) is described. Midgut cells are rich in mineral concretions and are presumably involved in excretory activity; the pyloric chamber, a cavity in the proturan intestine behind the midgut, is formed by cells with microvilli pointing anteriorly; the secretion from 6 Malpighian papillae flows into this cavity. The hindgut consists of 2 regions; the anterior of the 2 has a series of specializations typical of cells engaged in active water reabsorption. Long infoldings of the apical plasma membrane reach deep into the cells. The findings are compared with the gut organization of other genera of Protura examined to date.     

The ultrastructure of Malpighian tubules and hindgut of Frankliniella occidentalis (Pergande) (Thysanoptera : Thripidae)

The ultrastructure of the western flower thrips, Frankliniella occidentalis (Pergande) (Order : Thysanoptera), has 4 Malpighian tubules that are free of the intestine as they leave their junction at the pyloric region. The tubules consist of an epithelium with a single type of microvillated cells; proximally, the cells are lined by a thin cuticle. Numerous mitochondria, basal infoldings of the plasma membrane and vesicles with varying densities suggest active transit of fluid in the cell for osmoregulation. Two of the Malpighian tubules are bent posteriorly and closely adhere to the hindgut in the region of the rectal pads where the 2 epithelia are separated only by a basal lamina. The ultrastructure of this region suggests possible fluid reabsorption from the gut lumen.     

CELLULAR SPECIALIZATION IN THE EXCRETORY EPITHELIA OF AN INSECT, Macrosteles fascifrons STÅL (HOMOPTERA)

An electron microscopic investigation of the Malpighian tubules of a leaf hopper, Macrosteles fascifrons, shows that these organs comprise three quite distinct cell types, and the structure of these and of the mid- and hindgut epithelial cells is described. In particular, a comparison is made between the organization of the basal and apical surfaces of cells in the Malpighian tubule and in the vertebrate kidney, and it is suggested that similarities between these excretory epithelia reflect functional parallels between them. While the midgut and one region of the Malpighian tubule bear a typical microvillar brush border, elsewhere in the tubule and in the hindgut the apical surface bears cytoplasmic leaflets or lamellae. The sole solid excretory material of these insects consists of the brochosomes, secreted by cells of one region of the Malpighian tubule. The structure, geometry, and development of these unusual bodies, apparently formed within specialized Golgi regions, has been investigated, and histochemical tests indicate that they contain lipid and protein components.     

GATA factors as key regulatory molecules in the development of Drosophila endoderm

Essential roles for GATA factors in the development of endoderm have been reported in various animals. A Drosophila GATA factor gene, serpent ( srp , dGATAb , ABF ), is expressed in the prospective endoderm, and loss of srp activity causes transformation of the prospective endoderm into ectodermal foregut and hindgut, indicating that srp acts as a selector gene to specify the developmental fate of the endoderm. While srp is expressed in the endoderm only during early stages, it activates a subsequent GATA factor gene, dGATAe , and the latter continues to be expressed specifically in the endoderm throughout life. dGATAe activates various functional genes in the differentiated endodermal midgut. An analogous mode of regulation has been reported in Caenorhabditis elegans , in which a pair of GATA genes, end-1/3 , specifies endodermal fate, and a downstream pair of GATA genes, elt-2/7 , activates genes in the differentiated endoderm. Functional homology of GATA genes in nature is apparently extendable to vertebrates, because endodermal GATA genes of C. elegans and Drosophila induce endoderm development in Xenopus ectoderm. These findings strongly imply evolutionary conservation of the roles of GATA factors in the endoderm across the protostomes and the deuterostomes.     

Anatomy and fine structure of the alimentary canal of the spittlebug Lepyronia coleopterata (L.) (Hemiptera: Cercopoidea)

The alimentary canal of the spittlebug Lepyronia coleopterata (L.) differentiates into esophagus, filter chamber, midgut (conical segment, tubular midgut), and hindgut (ileum, rectum). The filter chamber is composed of the anterior extremity of the midgut, posterior extremity of the midgut, proximal Malpighian tubules, and proximal ileum; it is externally enveloped by a thin cellular sheath and thick muscle layers. The sac-like anterior extremity of the midgut is coiled around by the posterior extremity of the midgut and proximal Malpighian tubules. The tubular midgut is subdivided into an anterior tubular midgut, mid-midgut, posterior tubular midgut, and distal tubular midgut. Four Malpighian tubules run alongside the ileum, and each terminates in a rod closely attached to the rectum. Ultrastructurally, the esophagus is lined with a cuticle and enveloped by circular muscles; its cytoplasm contains virus-like fine granules of high electron-density. The anterior extremity of the midgut consists of two cellular types: (1) thin epithelia with well-developed and regularly arranged microvilli, and (2) large cuboidal cells with short and sparse microvilli. Cells of the posterior extremity of the midgut have regularly arranged microvilli and shallow basal infoldings devoid of mitochondria. Cells of the proximal Malpighian tubule possess concentric granules of different electron-density. The internal proximal ileum lined with a cuticle facing the lumen and contains secretory vesicles in its cytoplasm. Dense and long microvilli at the apical border of the conical segment cells are coated with abundant electron-dense fine granules. Cells of the anterior tubular midgut contain spherical secretory granules, oval secretory vesicles of different size, and autophagic vacuoles. Ferritin-like granules exist in the mid-midgut cells. The posterior tubular midgut consists of two cellular types: 1) cells with shallow and bulb-shaped basal infoldings containing numerous mitochondria, homocentric secretory granules, and fine electron-dense granules, and 2) cells with well-developed basal infoldings and regularly-arranged apical microvilli containing vesicles filled with fine granular materials. Cells of the distal tubular midgut are similar to those of the conical segment, but lack electron-dense fine granules coating the microvilli apex. Filamentous materials coat the microvilli of the conical segment, anterior and posterior extremities of the midgut, which are possibly the perimicrovillar membrane closely related to the nutrient absorption. The lumen of the hindgut is lined with a cuticle, beneath which are cells with poorly-developed infoldings possessing numerous mitochondria. Single-membraned or double-membraned microorganisms exist in the anterior and posterior extremities of the midgut, proximal Malpighian tubule and ileum; these are probably symbiotic.     

Morphology and ultrastructure of the alimentary canal of the cicada Platypleura kaempferi (Hemiptera: Cicadidae)

The alimentary canal of cicada Platypleura kaempferi is described. It comprises the oesophagus, filter chamber, external midgut section and hindgut. The elongate oesophagus expands posteriorly, with its posterior end constricting to become a bulb. The filter chamber consists of two parts: a very thin sheath and a filter organ. The filter organ is composed of the anterior and posterior ends of the midgut (internal midgut section), and the internal proximal ends of the Malpighian tubules. The external midgut section differentiates into a collapsed sac and a midgut loop. The latter is divided into three distinct segments. The hindgut contains a dilated rectum and a long narrow ileum. The distal portions of the four Malpighian tubules are enclosed in a peritoneal sheath together with the distal ileum before reaching to the rectum. Ultrastructurally, the oesophagus and the hindgut are lined with a cuticle. The filter chamber sheath consists of cells with large irregular nuclei. Filamentous substances coat the microvilli of the cells of the internal midgut section. The posterior end of the midgut comprises two types of cells, with the first type of cells containing many vesicles and scattered elements of rough endoplasmic reticulum. The anterior and posterior segments of the midgut loop cells have ferritin‐like granules. The ileum cells have well‐developed apical leaflets associated with mitochondria. Accumulations of virus‐like particles enclosed in the membrane are observed in the esophagus, conical segment, mid‐ and posterior segments of the midgut loop.     

光滑足距小蠹消化道的解剖结构

采用体视显微和扫描电镜技术研究光滑足距小蠹Xylosandrus germanus(Blandford)消化道的解剖结构。结果表明,光滑足距小蠹消化道由前肠、中肠和后肠三部分组成。成虫前胃由8个骨化的前胃板组成,呈灯笼状结构。前胃板由板状部和片状部组成,板状部短而简单,片状部甚长,由斜面、咀嚼刷和关闭刚毛组成。胃盲囊着生在中肠近后端,有细管状和囊状2种,成虫分别有1对,幼虫有1对细管状和3~5对囊状。6根马氏管分成2组,1组4根,另一组2根。6根马氏管与后肠肠壁形成隐肾系统。消化道具有1对囊状和1对细管状的胃盲囊可作为光滑足距小蠹成虫的识别特征。