Sixth Abdominal Segment Research Articles

Morphological diversity of male salivary glands in Panorpidae (Mecoptera)

The morphology of the male salivary glands of eighteen species of Panorpidae from China was studied using light micro- scopy. The results show that the male salivary glands differ markedly both at generic and specific levels. In Neopanorpa, the sali- vary glands consist of only two simple long secretory tubes extending to the fifth or sixth abdominal segment, whereas in Sinopanorpa, the salivary glands are composed of six extremely elongated secretory tubes. In Panorpa, the salivary glands are quite diverse, comprising two simple short secretory tubes only extending to the prothorax in the P. amurensis group (P. liui and P. jilin- ensis), six long tubes in the P. centralis group, eight to twelve in the P. diceras group and of a very variable number in the P. davidi group (especially in P. bifasciata and P. subambra). Morphology of the male salivary glands should be included in future studies on the systematics and phylogeny of the Panorpidae.

Histology and ultrastructure of the salivary glands and salivary pumps in the scorpionfly Panorpa obtusa (Mecoptera: Panorpidae)

AbstractLiu, S. and Hua, B. 2009. Histology and ultrastructure of the salivary glands and salivary pumps in the scorpionfly Panorpa obtusa (Mecoptera: Panorpidae). —Acta Zoologica (Stockholm) 91: 457–465.The morphology, histology and ultrastructure of the salivary glands and salivary pumps in the scorpionfly Panorpa obtusaCheng 1949 were investigated using light microscopy and scanning and transmission electron microscopy. The salivary glands display a distinct sexual dimorphism. The female has only two small sac‐like glands located in the prothorax, while the male possesses six long tubular glands extending into the sixth abdominal segment. The male salivary glands can be divided into five distinct regions. The apical long, thin secretory region possesses numerous secretory cells containing large secretory vesicles; the salivary reservoir expands in diameter, accumulating and temporarily storing the saliva in addition to secreting saliva; the constricted region contains prismatic cells with complex infolded plasma membrane; the sac has an internal brush border to absorb water and ions; the common salivary duct contains longitudinal muscles in the male, but not in the female. The salivary pump possesses independent strong dorsal muscles and abundant internal palm spines near its orifice. The anatomy and ultrastructure of the salivary glands and the salivary pump of scorpionflies as well as their possible functions are briefly discussed.

Visceral-Locomotory Pistoning in Crawling Caterpillars

Animals with an open coelom do not fully constrain internal tissues, and changes in tissue or organ position during body movements cannot be readily discerned from outside of the body. This complicates modeling of soft-bodied locomotion, because it obscures potentially important changes in the center of mass as a result of internal tissue movements. We used phase-contrast synchrotron X-ray imaging and transmission light microscopy to directly visualize internal soft-tissue movements in freely crawling caterpillars. Here we report a novel visceral-locomotory piston in crawling Manduca sexta larvae, in which the gut slides forward in advance of surrounding tissues. The initiation of gut sliding is synchronous with the start of the terminal prolegs' swing phase, suggesting that the animal's center of mass advances forward during the midabdominal prolegs' stance phase and is therefore decoupled from visible translations of the body. Based on synchrotron X-ray data and transmission light microscopy results, we present evidence for a two-body mechanical system with a nonlinear elastic gut that changes size and translates between the anterior and posterior of the animal. The proposed two-body system--the container and the contained--is unlike any form of legged locomotion previously reported and represents a new feature in our emerging understanding of crawling.

Identification and function of Abdominal‐A in the silkworm, Bombyx mori

Abdominal-A (adb-A) is a key gene in the development of insects. To understand its function in the silkworm, we cloned 1193 bp of the abd-A gene of Bombyx mori (Bmabd-A), including the complete coding sequence and part of the 3' untranslated region sequence. Bmabd-A has at least three mRNA splice variants with coding sequences of lengths 1032, 1044 and 1059 bp, encoding 343, 347 and 352 amino acids, respectively. Each splice variant of Bmabd-A has three exons and differs only in second exon size. Bmabd-A was expressed at low levels in unfertilized eggs, but increased gradually in fertilized eggs after laying 22 h. Bmabd-A expression decreased in ant silkworms (newly hatched silkworms). After RNA interference for Bmabd-A, the embryos had two mutant phenotypes, either completely or partially absent abdominal feet from the third to sixth abdominal segments, suggesting that Bmabd-A is responsible for normal development of the third to sixth abdominal segments during embryonic development.

A new shrimp species of the genus Leptomenaeus Bruce, 2007 (Crustacea: Decapoda: Pontoniinae) from Vietnam

A new species of pontoniine shrimp, Leptomenaeus nhatrangensis sp. nov., is described and illustrated. This new species is the second representative of the genus. It is distinguishable from L. dolichosternum (Okuno and Mitsuhashi 2003) by the straight dorsal outline of the carapace and rostrum (1), by the rostrum overreaching the basal antennular peduncle (2), a subacute lower orbital angle (3), serrate cutting edges on the first pereiopod chela (4), fingers of the second pereiopod chela not markedly longer than palm (5), and the sixth abdominal segment not distinctly longer than postorbital carapace length (6). A single specimen of this new species was found in shallows of the Nhatrang Bay, southeastern Vietnam, on the lower surface of a large boulder.

Breeding the Mite-Resistant Honeybee by Nutritional Crossbreed Technology

Mite ( Varroa destructor) is one of the most serious parasite threats to the honey bee ( Apis mellifera) reared in China. The beekeepers mainly use the drug to control and kill the mite in the past years, but the honey products may be contaminated and the mite is becoming drug-resistant. The main idea of this paper is to research the possibility of mite-resistant honeybee rearing by nutritional crossbreed. The larvae ( Apis mellifera ligustica) are bred with the royal jelly of Apis carana carana, and then the morphological index of the worker generation, genotypic frequency and gene frequency of the MDH II, genetic resemblance, and mite resistance are measured. The results show that: compared to the parent workers, the proboscis length, anterior wing area, the total length of the third and fourth dorsal plate of the abdomen, the length of the fourth dorsal plate of the tuberculum, the area of the sixth abdominal segment, and the area of wax mirrors are significantly different, but the differences in the brachium index, dactylus index, and wing claw are not significant. Moreover, there are some mutations in the genotypic frequency and gene frequency of the MDH II. The mite resistance of the nutritional crossbreed worker is significantly higher. The morphological, physical, and biochemical characters, genetic resemblance, and the mite-resistant ability of the worker generation can be changed by nutritional crossbreeding. Nutritional crossbreeding can be a new way to breed the honeybee.

Contribution to the Knowledge of the Xantholinini from China. I (Coleoptera, Staphylinidae)

The types of some Xantholinini (Coleoptera, Staphylinidae) from China are studied. The sixth male visible abdominal segment, genital segment and aedeagus are illustrated for the first time for Nepalinus parcipennis (Bernhauer), Hypnogyra hoffmanni (Bernhauer), Xantholinus semipallidus (Bernhauer); genital segment and aedeagus are illustrated also for Nudobius nigriventris Zheng and Gyrohypnus sichuanensis Zheng. The following new species are described: Stenistoderus sinicus n. sp. (Hopeh, Hebei, Shaanxi), Leptacinus harbinensis n. sp. (Harbin), Gyrohypnus wutaishanensis n. sp. (Shaanxi), Lepidophallus boki n. sp. (Shaanxi, Sichuan, Guizhou. Yunnan, Zhejiang, Hangzhou). Two new combinations are proposed: Hypnogyra hoffmanni (Bernhauer) and Nepalinus parcipennis (Bernhauer).

DNA supercoiling factor positively regulates expression of the homeotic gene Abdominal‐B in Drosophila melanogaster

DNA supercoiling factor (SCF) generates unconstrained negative supercoils of DNA in conjunction with eukaryotic topoisomerase II. In Drosophila melanogaster, SCF localizes to puffs on polytene chromosomes and is required for dosage compensation via hypertranscripton of genes on the male X chromosome. The present study investigated the role of SCF on autosomes. Although RNAi knockdown of scf results in male lethality, some escapers showed anterior homeotic transformation of the male sixth abdominal segment, similar to that arising from reduced expression of Abdominal-B (Abd-B). Heterozygotes for an scf mutant allele (scf(1)) displayed suppression of Pc mutation-dependent posterior transformation and enhancement of anterior transformation caused by trxG mutations. The level of Abd-B mRNA decreased in scf(1) embryos compared with wild-type. Tiling array experiments showed the presence of significant SCF signals in an Abd-B promoter region. Expression from the basal Abd-B promoter on a transgene was reduced in scf(1) embryos compared with wild-type. Collectively, these results demonstrate that SCF occupies the promoter region of Abd-B and activates expression for the proper formation of abdominal segments. Furthermore, preferential occupancy of SCF around transcription start sites of many active genes suggests a role for the factor in positive regulation of promoters.

VENT ASSOCIATED MUNIDOPSIS (DECAPODA: ANOMURA: GALATHEIDAE) FROM BROTHERS SEAMOUNT, KERMADEC ARC, SOUTHWEST PACIFIC, WITH DESCRIPTION OF ONE NEW SPECIES

A species of squat lobster, Munidopsis kermadec new to science is described and illustrated from a hydrothermal vent area in Brothers Seamount, Kermadec Volcanic Arc, Southwest Pacific Ocean. It is distinguished from the allied Munidopsis lauensis, by the shape of rostrum, the erectness of eye spines, structure of the sixth abdominal segment and dactyl morphology of P2-4. This new record increases the number of species of Munidopsis reported from Southwest Pacific vent fields to five. A key is provided to distinguish the vent associated Munidopsis. New records of M. lauensis and M. sonne from Brothers Seamount are also reported here and this extends their distribution further south to the western Pacific. The habitat of the new species is briefly described. A note on the Munidopsis diversity in West Pacific vent fields is also provided.

Regulation of Body Pigmentation by the Abdominal-B Hox Protein and Its Gain and Loss in Drosophila Evolution

Hox genes have been implicated in the evolution of many animal body patterns, but the molecular events underlying trait modification have not been elucidated. Pigmentation of the posterior male abdomen is a recently acquired trait in the Drosophila melanogaster lineage. Here, we show that the Abdominal-B (ABD-B) Hox protein directly activates expression of the yellow pigmentation gene in posterior segments. ABD-B regulation of pigmentation evolved through the gain of ABD-B binding sites in a specific cis-regulatory element of the yellow gene of a common ancestor of sexually dimorphic species. Within the melanogaster species group, male-specific pigmentation has subsequently been lost by at least three different mechanisms, including the mutational inactivation of a key ABD-B binding site in one lineage. These results demonstrate how Hox regulation of traits and target genes is gained and lost at the species level and have general implications for the evolution of body form at higher taxonomic levels.

External sensilla of the locust abdomen provide the central nervous system with an interganglionic network

External mechanoreceptors and contact chemoreceptors on the cuticle of the sixth abdominal segment of locusts have divergent primary projections of their sensory neurons that form arbours in the segmental and anterior abdominal ganglia. Homologous interganglionic projections from adjacent segments converge in the neuropile of each abdominal ganglion. Of the contributing types of sensilla, three were previously unknown for locust pregenital segments: tactile mechanosensory hairs with dual innervation, external proprioceptors of the hairplate type covered by intersegmental membranes and single campaniform sensilla that monitor cuticular strain in sternites and tergites. In general, interdependence of motor coordination in the abdominal segments is based on a neural network that relies heavily on intersegmental primary afferents that cooperate to identify the location, parameters and strength of external stimuli.

Width as an alternative measurement to length for post-mortem interval estimations using Calliphora augur (Diptera: Calliphoridae) larvae

The length of fly larvae collected from corpses is often used to help provide an entomological estimate of time since death. However, ‘head-curling’ by larvae can affect the accuracy of length measurements. To investigate a possible resolution to this problem, larvae of Calliphora augur were grown on sheep's liver at two constant temperatures (20 and 25 °C). Replicate samples were collected at set time intervals until pupation. Body length and width were measured for individual larvae and examined as predictors of age. It was found that body width, as measured at the junction of the fifth and sixth abdominal segments, is comparable with body length for age prediction of maggots of C. augur grown at these temperatures. Furthermore, conversion of width to length can be done with 95% accuracy from a simple linear model.

Sexing at the larval stage in two ant species of the Formicoxenini (Hymenoptera)

In contrast to the many studies of external morphology of hymenopteran larvae little is known on internal morphology, and especially on the structure of the reproductive organs. This study describes a simple histological method which allows a very accurate (100%) determination of male and female individuals from the very first larval instar to the fourth instar in two formicoxenine ant species. Both female and male gonads are located between the fifth and sixth abdominal segments dorsodistal from the midgut. The male gonads are larger than the female ones throughout all larval instars, and have a heart-like shape formed by a small nucleus cell type (spermatogonia) organised into four or five lobes. In contrast, female gonads are round in cross-section and are formed by two types of cells, large nucleus cells (oogonia) and small nucleus cells (prospective follicle cells). Larval sexing is equally successful as in whole larvae when only the posterior part of the larvae is used, so that the anterior part is available for further studies on ploidy, genetics or others. Due to the accuracy and effectiveness of this method already in the first instar larvae, it is a true alternative to the methods used so far for primary sex ratio determination. All of them have higher error rates in determining sex ratio.

Foil-setae, a new type of setae in the family Isotomidae (Collembola)Proceedings of the Xth international Colloquium on Apterygota, České Budějovice 2000: Apterygota at the Beginning of the Third Millennium

Summary A group of specialized setae on the sixth abdominal segment (foil setae) of Isotomidae are described. A survey of more than 100 species of family Isotomidae shows these setae to occur in certain species of several genera of subfamily Anurophorinae s.str. They are probably derived from macrosetae and are characterized by their unique shape. They appear to have evolved in several lineages and have fixed locations on the body.

Foil-setae, a new type of setae in the family Isotomidae (Collembola): Proceedings of the Xth international Colloquium on Apterygota, České Budějovice 2000: Apterygota at the Beginning of the Third Millennium

A group of specialized setae on the sixth abdominal segment (foil setae) of Isotomidae are described. A survey of more than 100 species of family Isotomidae shows these setae to occur in certain species of several genera of subfamily Anurophorinae s.str. They are probably derived from macrosetae and are characterized by their unique shape. They appear to have evolved in several lineages and have fixed locations on the body.

Maturation of muscle properties and its hormonal control in an adult insect.

The oviposition of female locusts requires longitudinal muscles to tolerate remarkable lengthening. Whether this ability together with concomitant properties develops during maturation or is present throughout life was investigated. The properties of the locust abdominal muscles involved in oviposition behaviour were investigated with respect to their maturation, segment- and gender-specificity and regulation by juvenile hormone (JH). Muscles from the sixth abdominal segment (an oviposition segment) of mature females (>18 days old) were able to tolerate large extensions (>8 mm). At this length, muscles were still able to generate considerable neurally evoked twitch tension. In contrast, muscle fibres from females less than 5 days old did not tolerate extension of more than 4 mm. At this length, tension generation was negligible. The maximum tension generated at different stimulus frequencies was significantly higher in muscles of females more than 18 days old than in females less than 5 days old. Furthermore, the cross-sectional area of muscle fibres increased significantly during reproductive development. Current-clamp recordings from denervated muscle fibres of females more than 18 days old revealed their ability to generate overshooting action potentials. The potentials were tetrodotoxin (TTX)-insensitive (0.5 micromol l(-1) TTX), but were blocked by Cd(2+) (50 micromol l(-1)) or nifedipine (50 micromol l(-1)), which suggests the involvement of L-type Ca(2+) channels. Action potentials recorded from females less than 5 days old differed considerably in amplitude and shape from those recorded from females more than 18 days old, suggesting their maturation during the first 2 weeks of adult life. Inactivation of the corpora allata (CA) by precocene inhibited the maturation of these muscle properties, whereas injection of JH into precocene-treated females reversed this effect. Homologous muscles from the third abdominal segment (a non-oviposition segment, M169) and muscles from males (M214) revealed no comparable changes, although some minor changes occurred during reproductive development. The results suggest a gender- and segment-specific maturation of muscle properties that is related to reproductive behaviour and controlled by JH.

Gene Expression in Black Tiger Prawns Following Intramuscular Injection of β-gal Plasmid

Gene expression in black tiger prawns (Penaeus monodon) was studied following intra-muscular injection of CMVβGal plasmid into the second abdominal segment. We used an in situ staining technique to detect β-gal expression in one- and three-month-old injected prawns. We found that only one of the three-month-old prawns expressed the marker gene (2 days after injection), and the site of expression was confined to the sixth abdominal segment away from the injection site. We repeated the experiment on a new batch of three-month-old prawns, but using fluorometric determination technique. This time we found that β-gal expression was detected (6/42) at the site of injection after 2, 7, and 14 days. In two other test samples, transgene expression was detected in the sixth abdominal segment only, further confirming the possibility of injected DNA dispersal. The results of the study also suggest that direct gene transfer is a feasible technique in black tiger prawns.

Transvection in the Drosophila Abd-B domain: extensive upstream sequences are involved in anchoring distant cis-regulatory regions to the promoter.

The Abd-B gene, one of the three homeotic genes in the Drosophila bithorax complex (BX-C), is required for the proper identity of the fifth through the eighth abdominal segments (corresponding to parasegments 10-14) of the fruitfly. The morphological difference between these four segments is due to the differential expression of Abd-B, which is achieved by the action of the parasegment-specific cis-regulatory regions infra-abdominal-5 (iab-5), -6, -7 and -8. The dominant gain-of-function mutation Frontabdominal-7 (Fab-7) removes a boundary separating two of these cis-regulatory regions, iab-6 and iab-7. As a consequence of the Fab-7 deletion, the parasegment 12- (PS12-) specific iab-7 is ectopically activated in PS11. This results in the transformation of the sixth abdominal segment (A6) into the seventh (A7) in Fab-7 flies. Here we report that point mutations of the Abd-B gene in trans suppress the Fab-7 phenotype in a pairing-dependent manner and thus represent a type of transvection. We show that the observed suppression is the result of trans-regulation of the defective Abd-B gene by the ectopically activated iab-7. Unlike previously demonstrated cases of trans-regulation in the Abd-B locus, trans-suppression of Fab-7 is sensitive to heterozygosity for chromosomal rearrangements that disturb homologous pairing at the nearby Ubx locus. However, in contrast to Ubx, the transvection we observed in the Abd-B locus is insensitive to the allelic status of zeste. Analysis of different deletion alleles of Abd-B that enhance trans-regulation suggests that an extensive upstream region, different from the sequences required for transcription initiation, mediates interactions between the iab cis-regulatory regions and the proximal Abd-B promoter. Moreover, we find that the amount of DNA deleted in the upstream region is roughly proportional to the strength of trans-interaction, suggesting that this region consists of numerous discrete elements that cooperate in tethering the iab regulatory domains to Abd-B. Possible implications of the tethering complex for the regulation of Abd-B are discussed. In addition, we present evidence that the tenacity of trans-interactions in the Abd-B gene may vary, depending upon the tissue and stage of development.

A NEW SPECIES OF ARRHOPALITES FROM MT. CHANGBAI, CHINA (COLLEMBOLA:SMINTHURIDAE)*

Abstract A new species, Arrhopalites chungbaishanensis is described from Mt. Changbai, northeast China. The present species shares some characters with A. octacanthus, but it differs from the latter by the number of vertical thick spines and manubrial dorsal setae, types of dental setae and the absence of tunica on unguis. In comparison with the other congeneric species, the mast striking character of the present species is its special shapes of the C‐series setae besetting on sixth abdominal segment.

Muscle activity underlying sexual behaviour in male locusts (Locusta migratoria) after normal and hormonally disturbed development

Abstract. . The activities of three sets of muscles, representing the major components of the abdominal muscle system, were recorded in the pregenital abdominal segments of adult males of Locusta migratoria. The muscular activities were associated with three consecutive actions of the male's mating behaviour: abdominal lowering, S‐bending and hooking‐up. These three actions depend mainly on the relative coordination of the dorsal versus ventral longitudinal muscles; the activity of the dorsoventral muscles is rather unpredictable, except in the sixth and seventh abdominal segments where they are regularly involved in hooking‐up. Studies on male sexual behaviour‐linked muscle activity in precocene‐induced fifth‐instar adultiforms and azadirachtin‐induced fifth‐instar over‐aged nymphs revealed no distinct differences between these creatures and normal mature males. Therefore the muscle activities associated with these adult‐specific behavioural acts can be released precociously, i.e. their occurrence is not dependent on a distinct series of instars. Moreover, the results obtained with over‐aged nymphs demonstrate that morphogenesis and ethogenesis (i.e. formation of neural circuits controlling adult‐specific behaviour) are not closely dependent on each other.