Number Of Body Segments Research Articles

Haasea Verhoeff, 1895—a genus of tumultuous history and chaotic records—redefinition, revision of taxonomy and geographic distributions, with descriptions of two new species from Austria and Serbia (Diplopoda, Chordeumatida, Haaseidae)

In this paper we revise the chordeumatidan genus Haasea Verhoeff, 1895 for the first time and describe two new species viz., H. gruberi sp. nov. and H. makarovi sp. nov. discovered in Austria and Serbia, respectively. A new terminology is proposed to standardize the description of the gonopod structures in the genus. Type material obtained from several institutions was examined and documented herein, whereby lectotypes are designated. We clarified the taxonomic status of a few taxa and consider the species H. norica (Verhoeff, 1913) and H. guidononveilleri Makarov, 2008 as a junior subjective synonyms of H. cyanopida (Attems, 1903) and H. vidinensis (Strasser, 1973a), respectively. The following subspecies or varieties, viz., Orobainosoma filicis ossiacum Verhoeff, 1939b, Orobainosoma flavescens vornatscheri Verhoeff, 1935, Orobainosoma hungaricum orientale Tabacaru, 1965, and Orobainosoma inflatum var. aspidiorum Verhoeff, 1929 are here regarded as junior subjective synonyms of their nominal taxa. The taxonomic relationships within the genus Haasea are discussed and an identification key to its 17 species is presented, based on number of body segments and gonopod structures. Maps showing species occurences based on historical and recent records are presented to understand their respective geographic ranges. H. flavescens is now deleted from the list of species in Croatia, Bosnia and Herzegovina, Slovenia and Italy as these records were based on misidentified material. H. inflata is deleted from the fauna of Bosnia and Herzegovina, whereas H. hungarica is newly recorded from Austria, Serbia and Slovenia.

Analysis and modeling of human seat interaction with a focus on the upper body and backrest using biomechanics and contact mechanics.

This paper outlines a method to study the interaction between the human body and the aircraft seat concerning the seat comfort. Firstly, the human body is modeled based on biomechanics and divided into a number of body segments connected by joints according to human anatomy. The angles between the body segments are obtained by curve fitting of the existing biomechanical research data. The contact forces between the human body and the seat are modeled using pairs of bi-lateral point forces. These forces are calculated and located through the analysis of the center of gravity of each body segment and average muscular structure of the human body. The geometry of the human and the seat is obtained from a 3D scan model or a CAD model. Secondly, the pressure distribution between the human body and the seat is modeled and calculated using the contact stress theory. The results of the two parts are combined to analyze the comfortability in relation to different postures, backrest recline angles and changing in shape and material. Simulations were performed and they are compared with experimental measurement and various FEM studies for validation. It is found that accuracy of this method is comparable with most FEM calculation. This method provides a new direction in cushion conform research. It is faster and convenient to use comparing to the FEM, and the result is reliable.

Abdominal segment deformity syndrome (asds) and fused body segment deformity (fbsd) in cultured Penaeus indicus

The abdominal segment deformity disease (ASDD) is a new shrimp disease reported only in cultured Penaeus vannamei in Thailand. Shrimp with ASDD have deformed abdominal segment, jagged gut line and bumpy surfaces. Similar signs were observed in cultured P. indicus in the Philippines. However, aside from the signs described for ASDD, some P. indicus showing abdominal segment deformity syndrome (ASDS) had more severe deformities up to the extent that the number of body segments was reduced due to fusion. Shrimp with fused body segment deformity (FBSD) had four instead of five pairs of legs. To account the prevalence of the deformities in P. indicus, shrimp were classified into grossly normal shrimp (NS), shrimp with abdominal segment deformity syndrome (ASDS) and shrimp with fused segments (FBSD). Out of the shrimp sampled, 83.4±5.4% was NS, 10.9±6.2% was ASDS and 5.7±3.0% was FBSD. Morphometric characteristics of the shrimp were measured. There was no significant difference in body weight (BW) among male and female NS, ASDS and FBSD. In both sexes, total length (TL) of FBSD was significantly shorter compared to NS and ASDS. Shrimp samples were also screened to be negative for known infectious viral diseases including white spot syndrome virus (WSSV), infectious hypodermal and haematopoietic necrosis virus (IHHNV), infectious myonecrosis virus (IMNV), P. vannamei nodavirus (PvNV), Macrobrachium rosenbergii nodavirus (MrNV) and Taura syndrome virus (TSV). Occurrence of ASDS and FBSD in post-larvae (PL) produced from captive and wild spawners were also determined. Based on a tank experiment, no significant difference was detected between the percentages of ASDS in PL produced from wild or captive spawners but FBSD was only noted in PL produced from the latter. Deformities generally did not affect the size of P. indicus except for the reduced length of shrimp with FBSD which when coupled with missing pleopods could lead to major economic loss for shrimp farmers if not addressed properly. Statement of relevanceShrimp is a major aquaculture commodity in the world but the industry has always struggled because of disease outbreaks. Abdominal segment deformity disease (ASDD) is a Penaeus vannamei disease recently reported. Similar pathological signs were observed in tank and pond cultured Penaeus indicus in the Philippines. This paper provided the first information on the abdominal segment deformity syndrome and fused body segment deformity in P. indicus. Data on the prevalence, morphometric characteristics and influence of sourced (captive or wild broodstock) were presented in this study.

Morphology and development of immature stages of Chelonus murakatae (Hymenoptera: Braconidae), an endoparasitoid of Chilo suppressalis.

ABSTRACT: The Braconid parasite Chelonus muarakatae is one of the dominant natural enemies of Chilo suppressalis. Morphology and development of this parasitoid developing in host larvae are rarely mentioned. In the current study, morphological characters and developmental duration of each immature stage of C. murakatae were recorded after dissecting parasitized hosts. The egg of C. murakatae is oval and hymenopteriform. Based on changes in number of body segments, visibility of the anal vesicle and measurement of the head capsule width, it was determined that there are three larval instars. The third instar mature larvae drilled the host body and pupated in a cocoon. Development time from egg to adult emergence was about 34 days at 27.5°C and a photoperiod of 15:9 (L:D) h with a relative humidity of 70–85%. All stages are shown with photomicrographs. This study will be helpful for better understanding of the physiological interactions between C. murakatae and its host.

J027021 タコ型推進機構のシミュレーションモデルの開発([J027-02]生物規範メカニクス・システム:生物の運動,力学及びミメティクス(2))

The simulation model for the swimming movement of octopus was developed. This model was developed by extending SWUM (swimming human simulation model). In SWUM, a human body is represented by 21 body segments. However, it was not enough to realize the smooth arm motion of octopus. Therefore, in the octopus model, the number of body segments was increased to 90 (the body and 8 arms consisted of 10 body segments for each). Each joint had 3 degrees of freedom to realize various motions. This study aimed to clarify the motion and shape for fast swimming to develop an octopus-inspired robot for underwater rescue and exploration by using this octopus model. Three arm motions (sculling, undulation, and their composition) were analyzed. As a result, the average velocity in the last cycle of each motions were 0.08 lm/s in the sculling motion, 0.023m/s in the undulation motion and 0.106m/s in the composition motion. In future, we will investigate the fluid force coefficients to improve the precision of the model and investigate the arm motion suitable for the octopus-inspired robot.

Variation in body segment number within and between populations of the centipedeStrigamia maritima(Chilopoda: Geophilomorpha)

Although most arthropod species have a fixed number of body segments, one order of centipedes – the Geophilomorpha – provides an unusual opportunity to study the variation and microevolution of segment number. This is because all species in all but one family exhibit variation in the number of leg-bearing segments (LBS) within and between natural populations. One species in particular, the coastal geophilomorph Strigamia maritima, has become a ‘model system’ for these studies, because of its high population densities and the consequent ease of collecting large samples. Previous studies on this species have examined various aspects of segment number variation. However, most studies have characterized each population by an LBS distribution and a mean LBS number that are based on data from all life-stages. Here, we dissect the variation within as well as between populations and show that different cohorts within a population often have significantly different LBS number distributions. This is almost certainly due to developmental plasticity, probably related to the prevailing microhabitat temperature within brood chambers, but possibly related to other environmental factors too. Although we found no evidence of selection, the fact that different species of geophilomorphs have different LBS distributions suggests that, in the long term, selection may act on the developmental reaction norm of LBS number. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 107, 678–685.

Evolution of the axial skeleton in armadillos (Mammalia, Dasypodidae)

Intraspecific and interspecific variation in cervical, thoracic, and lumbar region of the vertebral column of Dasypodidae were examined in a phylogenetic framework. The number of vertebrae for each region were recorded for 86 specimens and metric data for each vertebra (centrum length, high, and width) were recorded for 72 specimens, including eight of the nine living genera. The number of vertebrae and degree of fusion between them were used to define four characters which were plotted on two alternative phylogenies of Dasypodidae. The ratio between centrum height and width is similar across all taxa analyzed except for Chlamyphorus, which exhibits a deviation in the last two lumbars. Tolypeutes matacus is unique among the taxa examined in having a second co-osified bone called postcervical bone, which is a fusion of the seventh cervical and first thoracic vertebrae. The thoraco-lumbar numbers of dasypodids are reduced when compared with other xenarthrans and are more diverse than those of some other mammalian clades of similar geological age and higher ecomorphological diversity. Changes in size are somewhat coupled with changes in the number of body segments. Independent of the phylogenetic framework taken, changes in size are accompanied with small changes in numbers of thoracolumbar vertebrae within each genus. There are functional and phylogenetic correlates for changes in number of thoraco-lumbar vertebrae in dasypodids.

A New View of the Cambrian Arthropod Fuxianhuia

Fuxianhuia from the Chengjiang fauna is one of the least derived Cambrian arthropods. A supposed pair of hook-shaped post-antennal appendages (Chen et al. 1995) was later reinterpreted as a pair of gut diverticula situated in a carapace fold (Waloszek et al. 2005). The latter interpretation of the diverticular nature of this structure is verified, but we show that the diverticula are situated inside a head capsule. This capsule carries a pair of antennae. It is shown that the head has also a pair of ordinary locomotory limbs. It is also demonstrated that a number of body segments have more than one pair of legs. There is indication of a possible pair of small eyes in addition to the large pair. The gut may include sediment from the substrate, which indicates that sediment was ingested. Fuxianhuiids share with many lobopodians characters such as a lack of specialisation between and within the ventral appendages. The exopod rises as a lateral fold on a straight limb axis, indicating an origin as a secondary addition to a uniramous limb. The terms Arthropoda s.l. (or pan-Arthropoda) and Arthropoda s.s. are replaced by Aiolopoda Hou & Bergström, 2006, and Arthropoda (in the original sense). The origination of the arthropods is discussed.

Climate affects embryonic development in a viviparous snake, Vipera aspis

Climatic conditions during embryonic development can exert profound and long‐term effects on many types of organisms, but most previous research on this topic has focussed on endothermic vertebrates (birds and mammals). Although viviparity in ectothermic taxa allows the reproducing female to buffer ambient thermal variation for her developing offspring, even an actively thermoregulating female may be unable to provide optimal incubation regimes in severe weather conditions. We examined the extent to which fluctuations in natural thermal conditions during pregnancy affect reproduction in a temperate viviparous snake, the aspic viper (Vipera aspis). Data gathered from a long term field study demonstrated that ambient thermal conditions influenced (1) female body temperatures and (2) gestation length, embryo viability, and offspring phenotypes. Interestingly, thermal conditions during each of the three months of gestation affected different aspects of reproduction. Hotter weather early in gestation (June) increased ventral scale counts (=number of body segments) of neonates; hotter weather mid‐gestation (July) hastened development and thus the date of parturition; and hotter weather late in gestation (August) reduced the incidence of stillborn neonates. The population that we studied is close to the northern limit of the species’ range, and embryonic thermal requirements may prevent Vipera aspis from extending into cooler conditions further north.

Analysis of neurofibromatosis 1 (NF1) lesions by body segment.

Café-au-lait spots and neurofibromas are defining features of neurofibromatosis 1 (NF1), but they vary greatly in number, size, and clinical importance from patient to patient. The cause of this variability is unknown. We tested the hypotheses that development of these lesions is influenced by local or familial factors. The presence or absence of café-au-lait spots, cutaneous neurofibromas, and diffuse plexiform neurofibromas was recorded for each of 10 divisions of the body surface in 547 NF1 patients, including 117 affected individuals in 52 families. We used stratified Mantel-Haenszel tests to look for local associations between the presence of diffuse plexiform neurofibromas, cutaneous neurofibromas, and café-au-lait spots in individual body segments of NF1 patients. We used a random effects model to obtain intrafamilial correlation coefficients for the age-adjusted number of body divisions affected with each of the three lesions. No significant association was observed between the occurrence of cutaneous and diffuse plexiform neurofibromas, between café-au-lait spots and cutaneous neurofibromas, or between café-au-lait spots and plexiform neurofibromas in the same body segment. The correlation among relatives in the number of body segments affected with café-au-lait spots was 0.45 (95% confidence interval [CI] = 0.18-0.71), with cutaneous neurofibromas, 0.37 (95% CI = 0.15-0.55), and with plexiform neurofibromas, 0.35 (95% CI = 0.15-0.57). We conclude that the development of café-au-lait spots, cutaneous neurofibromas, and plexiform neurofibromas are spatially independent in NF1 patients but that the development of all three lesions is influenced by familial factors.

Body size and segmentation patterns in free-living and parasitic polychaetes

Taxa that include both free-living and parasitic lineages present opportunities to examine if and how the life-history traits of parasitic organisms have diverged from those of their free-living relatives. In a comparative analysis the body sizes and numbers of body segments of parasitic polychaetes of the family Oenonidae were compared with those of free-living polychaetes from closely related families. There was no difference in body length between oenonids and free-living polychaetes. However, the parasitic oenonids attain, on average, a much higher number of body segments than their free-living counterparts. The number of segments per unit body length is also much higher in oenonids than in related free-living polychaetes. This suggests that new segments are produced at a higher rate or for longer periods in oenonids than in free-living polychaetes, in which the proliferation of new segments slows down over time to allow for the segments to grow in size. Given that each segment can produce gametes late in the life of the worm, the proliferation of segments in oenonids may be an adaptation to their parasitic life-style.

Development of Three-Diemnsional Whole-Body Musculoskeletal Model for Various Motion Analyses

A simulation model for biomechanical analysis was developed in order to calculate the internal loads, such as muscular tension and energy consumption, from measured kinesiological data for various kinds of motion. In this model, the human body is divided into a maximum of nineteen rigid segments connected to each other with ball joints. A maximum of 156 skeletal muscles throughout the body are modeled as tensile force generators which include physiological elements that consume mechanical energy. The component ratio among muscle fiber types, number of body segments and number of degrees of jointfreedom can be changed easily, and according to the alteration of the segment number, the musculoskeletal system is changed automatically. This flexibility is of benefit in application of the method to various motion analyses. Three-dimensional bipedal walking was analyzed using a simplified model, and rowing motions were analyzed using the whole-body model.

Morphology and number of neurons in two species of polychaetes.

Neurons of the ventral nerve cord (VNC) in the polychaete species Clymenella torquata and Nereis virens were ultrastructurally distinguished from glial cells by the smaller diameter and elongated shape of glial nuclei in adult organisms. In contrast to neurons, beta-glycogen-like particles and densely packed microfilaments were found in glial cytoplasm. Using these and other criteria, glial cells were distinguished from nerve cells in histologic preparations. All neuronal nuclei were counted in specified regions of the CNS of both polychaetes. In both species, the number of neuronal nuclei in various CNS regions remained constant in animals of very different body size. Since Clymenella has a set number of ganglia in the VNC and a set number of body segments, the total number of CNS neurons remains constant in adult members of this species. Since adult Nereis adds VNC ganglia in newly forming body segments, the total number of CNS neurons continuously increases, but the total number of CNS neurons in a ganglion does not change after it is formed.

Regulation of segment-building during the postembryonic development of a common milliped.

Starvation of larvae of the milliped Narceus annularis results in the formation of a smaller than normal number of body segments in the early stadia. However, this reduced number is compensated for by subsequent formation of a larger than normal number of body segments in the later stadia, or by the addition of extra segment-building stadia. Apparently there is a mechanism whereby the milliped "keeps count" of the number of body segments produced and can regulate the production of these segments from a proliferative region so that the total number of body segments at sexual maturity is within the normal range for the species.

The significance for the theory of heredity of the reduction in the number of body segments in Drosophila melanogaster through rigorous selection

The significance for the theory of heredity of the reduction in the number of body segments in Drosophila melanogaster through rigorous selection