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Arthropod Structure & Development

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https://www.readbyqxmd.com/read/27720841/linking-gene-regulation-to-cell-behaviors-in-the-posterior-growth-zone-of-sequentially-segmenting-arthropods
#1
REVIEW
Terri A Williams, Lisa M Nagy
Virtually all arthropods all arthropods add their body segments sequentially, one by one in an anterior to posterior progression. That process requires not only segment specification but typically growth and elongation. Here we review the functions of some of the key genes that regulate segmentation: Wnt, caudal, Notch pathway, and pair-rule genes, and discuss what can be inferred about their evolution. We focus on how these regulatory factors are integrated with growth and elongation and discuss the importance and challenges of baseline measures of growth and elongation...
February 15, 2017: Arthropod Structure & Development
https://www.readbyqxmd.com/read/27725255/a-molecular-view-of-onychophoran-segmentation
#2
Ralf Janssen
This paper summarizes our current knowledge on the expression and assumed function of Drosophila and (other) arthropod segmentation gene orthologs in Onychophora, a closely related outgroup to Arthropoda. This includes orthologs of the so-called Drosophila segmentation gene cascade including the Hox genes, as well as other genetic factors and pathways involved in non-drosophilid arthropods. Open questions about and around the topic are addressed, such as the definition of segments in onychophorans, the unclear regulation of conserved expression patterns downstream of non-conserved factors, and the potential role of mesodermal patterning in onychophoran segmentation...
February 14, 2017: Arthropod Structure & Development
https://www.readbyqxmd.com/read/28108399/fine-structure-of-the-anterior-median-eyes-of-the-funnel-web-spider-agelena-labyrinthica-araneae-agelenidae
#3
Wolfgang-D Schröer
Only few electron microscopic studies exist on the structure of the main eyes (anterior median eyes, AME) of web spiders. The present paper provides details on the anatomy of the AME in the funnel-web spider Agelena labyrinthica. The retina consists of two separate regions with differently arranged photoreceptor cells. Its central part has sensory cells with rhabdomeres on 2, 3, or 4 sides, whereas those of the ventral retina have only two rhabdomeres on opposite sides. In addition, the rhabdomeres of the ventral retina are arranged in a specific way: Whereas in the most ventral part they form long tangential rows, those towards the center are detached and are arranged radially...
February 10, 2017: Arthropod Structure & Development
https://www.readbyqxmd.com/read/28189833/the-morphology-and-ultrastructure-of-salivary-glands-of-zoraptera-insecta
#4
R Dallai, D Mercati, Y Mashimo, R Machida, R G Beutel
The salivary glands of two species of Zoraptera, Zorotypus caudelli and Zorotypus hubbardi, were examined and documented mainly using transmission electron microscopy (TEM). The results obtained for males and females of the two species are compared and functional aspects related to ultrastructural features are discussed. The salivary glands are divided into two regions: the secretory cell region and the long efferent duct, the latter with its distal end opening in the salivarium below the hypopharyngeal base...
February 9, 2017: Arthropod Structure & Development
https://www.readbyqxmd.com/read/27871863/muscular-system-in-interna-of-peltogaster-paguri-rhizocephala-peltogastridae
#5
Aleksei A Miroliubov
Rhizocephalan parasites have a peculiar life cycle, and their adults lost almost all traits found usually in Crustacea. Despite some data on anatomy and ultrastructure of interna of Peltogastridae, some crucial aspects of morphology are still unknown. For example, there is only one mentioning of myocytes found in interna of Rhizocephalans (Sacculina carcini). So we aimed at studying the muscular system of the interna of Peltogaster paguri using serial histological sectioning and fluorescent staining (TRITC-labeled phalloidin) with confocal microscopy...
February 9, 2017: Arthropod Structure & Development
https://www.readbyqxmd.com/read/28062354/comparative-study-of-the-morphology-of-the-female-seminal-receptacles-of-ilia-nucleus-and-persephona-mediterranea-decapoda-brachyura-leucosiidae
#6
Sarah Hayer, Stephanie Köhnk, Christoph D Schubart, Susann Boretius, Stanislav N Gorb, Dirk Brandis
Because of the poor knowledge of the morphology of the female reproductive organs of most brachyuran crabs, this study investigated two Atlantic representatives of the family Leucosiidae, Ilia nucleus (Linnaeus, 1758) and Persephona mediterranea (Herbst, 1794), using histological methods and magnetic resonance imaging (MRI). While the vagina conforms to the concave type, the arrangement of the two chambers of the seminal receptacle differs strongly from that of other eubrachyuran sperm storage organs. Both chambers are oriented laterally within the crab's body...
February 8, 2017: Arthropod Structure & Development
https://www.readbyqxmd.com/read/28163192/sperm-ultrastructure-of-shrimp-from-family-penaeidae-crustacea-dendrobranchiata-in-a-phylogenetic-context
#7
Tavani Rocha Camargo, Natalia Rossi, Antonio L Castilho, Rogério C Costa, Fernando L Mantelatto, Fernando José Zara
We describe the sperm ultrastructure of six Penaeidae species, including at least one member of each tribe (Penaeini, Parapenaeini and Trachypenaeini). Fragments of the vas deferens of the Penaeidae Farfantepenaeus brasiliensis, F. paulensis, Litopenaeus schmitti, Parapenaeus americanus, Rimapenaeus constrictus and Xiphopenaeus kroyeri were fixed and processed according to the routine for transmission electron microscopy. The morphological results were contextualized in an evolutionary perspective using molecular markers for the phylogenetic reconstruction of this group...
February 2, 2017: Arthropod Structure & Development
https://www.readbyqxmd.com/read/28161605/haltere-morphology-and-campaniform-sensilla-arrangement-across-diptera
#8
Sweta Agrawal, David Grimaldi, Jessica L Fox
One of the primary specializations of true flies (order Diptera) is the modification of the hind wings into club-shaped halteres. Halteres are complex mechanosensory structures that provide sensory feedback essential for stable flight control via an array of campaniform sensilla at the haltere base. The morphology of these sensilla has previously been described in a small number of dipteran species, but little is known about how they vary across fly taxa. Using a synoptic set of specimens representing 42 families from all of the major infraorders of Diptera, we used scanning electron microscopy to map the gross and fine structures of halteres, including sensilla shape and arrangement...
February 1, 2017: Arthropod Structure & Development
https://www.readbyqxmd.com/read/28065803/ontogenetic-trajectory-and-allometry-of-diplonychus-rusticus-fabricius-an-oriental-aquatic-bug-hemiptera-belostomatidae-from-the-western-ghats-of-india
#9
Dnyaneshwar Doke, Rashmi Morey, Neelesh Dahanukar, Sameer M Padhye, Shruti V Paripatyadar
Despite being one of the dominant groups in freshwater ecosystems, morphological and ontogenetic studies on aquatic Hemiptera have received little attention in the Oriental region. We present the ontogenetic trajectory and allometry of the widespread Oriental belostomatid species, Diplonychus rusticus (Fabricius) for the first time. We have measured nine different morphological variables throughout the growth of the bug using both field captured and laboratory reared specimens. Our results suggest that the developmental instars can be distinguished by the size variables, as seen in the Principal Component Analysis...
January 28, 2017: Arthropod Structure & Development
https://www.readbyqxmd.com/read/28115255/formation-of-the-acrosome-complex-in-the-bush-cricket-gampsocleis-gratiosa-orthoptera-tettigoniidae
#10
Cai Xia Su, Jie Chen, Fu Ming Shi, Ming Shen Guo, Yan Lin Chang
The acrosome complex plays an indispensable role in the normal function of mature spermatozoa. However, the dynamic process of acrosome complex formation in insect remains poorly understood. Gampsocleis gratiosa Brunner von Wattenwyl possesses the typical characteristic of insect sperms, which is tractable in terms of size, and therefore was selected for the acrosome formation study in this report. The results show the acrosome formation can be divided into six phases: round, rotating, rhombic, cylindrical, transforming and mature phase, based on the morphological dynamics of acrosome complex and nucleus...
January 20, 2017: Arthropod Structure & Development
https://www.readbyqxmd.com/read/27998741/the-scolopidial-accessory-organ-in-the-jerusalem-cricket-orthoptera-stenopelmatidae
#11
Johannes Strauß
Multiple mechanosensory organs form the subgenual organ complex in orthopteroid insects, located in the proximal tibia. In several Ensifera (Orthoptera), a small chordotonal organ, the so-called accessory organ, is the most posterior part of this sensory complex. In order to document the presence of this accessory organ among the Ensifera, the chordotonal sensilla and their innervation in the posterior tibia of two species of Jerusalem crickets (Stenopelmatidae: Stenopelmatus) is described. The sensory structures were stained by axonal tracing...
January 4, 2017: Arthropod Structure & Development
https://www.readbyqxmd.com/read/27939748/the-length-of-a-short-sperm-elongation-and-shortening-during-spermiogenesis-in-cotesia-congregata-hymenoptera-braconidae
#12
Rustem Uzbekov, Julien Burlaud-Gaillard, Anastasiia S Garanina, Christophe Bressac
The spermatozoon of the parasitoid wasp Cotesia congregata is an extremely short gamete measuring less than 7 μm; it is as yet the shortest flagellated sperm to be identified. The mature sperm consists of an acrosome, surrounded by an extra cellular coat, a condensed nucleus, two uncoiled mitochondrial derivatives and a short axoneme. Testes of young adults contain a continuum of differentiation stages. Initially, the flagellum is approximately 5 μm long. It conserves its length in round, elongated and mature spermatids, but is reduced to less than 3 μm in mature spermatozoa...
January 4, 2017: Arthropod Structure & Development
https://www.readbyqxmd.com/read/27919803/germ-cell-proliferation-and-cluster-behavior-in-ovarioles-of-sialis-flavilatera-megaloptera-sialidae-during-larval-growth
#13
Ralph Rübsam, Jürgen Büning
Telotrophic meroistic insect ovaries are assigned to four different types. The Sialis type is found in Sialidae (Megaloptera), Raphidioptera and a coleopteran subgroup (Myxophaga: Hydroscaphidae). King and Büning (1985) proposed a hypothetical model for the development of this ovariole type; however, a detailed description of ovarian development in Sialis was missing so far. Using light and electron microscopy, we investigated developing ovaries of Sialis flavilatera starting in the 10th month of the biennial larval phase until adulthood...
January 4, 2017: Arthropod Structure & Development
https://www.readbyqxmd.com/read/28043917/stylet-biogenesis-in-bactericera-cockerelli-hemiptera-triozidae
#14
Joseph M Cicero
The discovery of 'Ca. Liberibacter solanacearum', causal agent of certain solanaceous and apiaceous crop diseases, inside the functional (intrastadial) and pharate stylet anatomy of the potato psyllid prompted elucidation of the mechanism of stylet replacement as a novel exit portal in the transmission pathway. In Hemiptera, presumptive (formative) stylets, secreted during consecutive pharate instars, replace functional stylets lost with the exuviae. In potato psyllids, each functional stylet has a hollow core filled with a cytology that extends out of the core to form a hemispherical aggregate of cells, the 'end-cap', somewhat resembling a golf ball on a tee...
December 30, 2016: Arthropod Structure & Development
https://www.readbyqxmd.com/read/28017815/ultrastructure-of-chemoreceptive-tarsal-sensilla-in-an-armored-harvestman-and-evidence-of-olfaction-across-laniatores-arachnida-opiliones
#15
Guilherme Gainett, Peter Michalik, Carsten H G Müller, Gonzalo Giribet, Giovanni Talarico, Rodrigo H Willemart
Harvestmen (Arachnida, Opiliones) are especially dependent on chemical cues and are often regarded as animals that rely mainly on contact chemoreception. Information on harvestman sensilla is scarce when compared to other arachnid orders, especially concerning internal morphology. Using scanning (SEM) and transmission (TEM) electron microscopy, we investigated tarsal sensilla on the distal tarsomeres (DT) of all leg pairs in Heteromitobates discolor (Laniatores, Gonyleptidae). Furthermore, we explored the typological diversity of sensilla present on the DT I and II in members of the suborder Laniatores, which include two thirds of the formally described opilionid fauna, using species from 17 families representing all main laniatorian lineages...
December 22, 2016: Arthropod Structure & Development
https://www.readbyqxmd.com/read/27847335/patterns-of-inner-chorion-structure-in-anastrepha-diptera-tephritidae-eggs
#16
Julia V A Figueiredo, André L P Perondini, Denise Selivon
The inner chorion structure of Anastrepha eggs from 16 species of various infrageneric taxonomic groups is described by scanning and transmission electron microscopy. The layers of the chorion, the outer egg membrane, are structurally similar. Furthermore, an additional trabecular layer (ATL) that exists in some species, together with other characteristics, facilitates the recognition of four patterns of chorion structuring: Pattern I, in which the ATL layer is absent, is found in Anastrephaamita, the Anastrepha fraterculus complex, Anastrepha obliqua, Anastrepha sororcula, Anastrephasuspensa and Anastrephazenildae (fraterculus group), and Anastrephabistrigata and Anastrephastriata (striata group); Pattern II in Anastrephaserpentina (serpentina group), Anastrephagrandis (grandis group) and Anastrephapseudoparallela (pseudoparallela group), in which the ATL presents large open spaces with pillars; Pattern III, found in Anastrephaconsobrina (pseudoparallela group), in which the ATL is composed of round cavities; and Pattern IV, found in Anastrephaalveata and Anastrephapickeli (spatulata group), where the large ATL cavities are reticulated...
December 22, 2016: Arthropod Structure & Development
https://www.readbyqxmd.com/read/28012892/head-anatomy-of-adult-coniopteryx-pygmaea-enderlein-1906-effects-of-miniaturization-and-the-systematic-position-of-coniopterygidae-insecta-neuroptera
#17
Susanne Randolf, Dominique Zimmermann, Ulrike Aspöck
External and internal head structures of adult Coniopteryx pygmaea Enderlein, 1906, one of the smallest known lacewings, are described in detail for the first time. Possible effects of miniaturization and two hypotheses on the phylogenetic position of Coniopterygidae are evaluated and compared with data from literature. Several convergent modifications in C. pygmaea and other miniaturized insect species are outlined, e.g., a relative increase in the size of the brain, simplification of the tracheal system with respect to the number of tracheae, and reduction of the number of ommatidia and diameter of the facets...
December 21, 2016: Arthropod Structure & Development
https://www.readbyqxmd.com/read/27888167/delta-notch-signalling-in-segmentation
#18
REVIEW
Bo-Kai Liao, Andrew C Oates
Modular body organization is found widely across multicellular organisms, and some of them form repetitive modular structures via the process of segmentation. It's vastly interesting to understand how these regularly repeated structures are robustly generated from the underlying noise in biomolecular interactions. Recent studies from arthropods reveal similarities in segmentation mechanisms with vertebrates, and raise the possibility that the three phylogenetic clades, annelids, arthropods and chordates, might share homology in this process from a bilaterian ancestor...
December 19, 2016: Arthropod Structure & Development
https://www.readbyqxmd.com/read/27998742/structure-and-postembryonic-development-of-the-intersegmental-nodules-in-the-non-muscular-joints-of-the-antennae-in-rhodnius-prolixus
#19
Bibiana Ospina-Rozo, Manu Forero-Shelton, Jorge Molina
The antennae of Insecta consist of two basal segments and the distal annulated flagellum lacking intrinsic muscles. Non-muscular joints are important to preserve the flexibility and structure of the long Heteropteran antennae which bears an intersegmental nodule on each non-muscular joint. Little is known about their properties or function. Here we characterize the structure and postembryonic development of the non-muscular joints of Rhodnius prolixus antennae. Using Scanning Electron Microscopy, we tracked the changes in shape and size of both intersegmental nodules during the course of the hemimetabolous insect life cycle...
December 17, 2016: Arthropod Structure & Development
https://www.readbyqxmd.com/read/27989966/origin-and-evolution-of-the-panarthropod-head-a-palaeobiological-and-developmental-perspective
#20
Javier Ortega-Hernández, Ralf Janssen, Graham E Budd
The panarthropod head represents a complex body region that has evolved through the integration and functional specialization of the anterior appendage-bearing segments. Advances in the developmental biology of diverse extant organisms have led to a substantial clarity regarding the relationships of segmental homology between Onychophora (velvet worms), Tardigrada (water bears), and Euarthropoda (e.g. arachnids, myriapods, crustaceans, hexapods). The improved understanding of the segmental organization in panarthropods offers a novel perspective for interpreting the ubiquitous Cambrian fossil record of these successful animals...
December 17, 2016: Arthropod Structure & Development
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