Neural mechanisms governing distribution of cardiac output in an isopod crustacean,Bathynomus doederleini: reflexes controlling the cardioarterial valves

In Bathynomus doederleini all of the cardioarterial valves located at the origin of the lateral arteries are dilated by impulses of lateral cardiac nerves. Tactile stimuli applied to sensillar setae depress impulse activities of the 1st and 5th lateral cardiac nerves. The 1st lateral cardiac nerve controls the valve of the lateral artery which runs to the walking-legs and viscera. The 5th lateral cardiac nerve controls the valve of the lateral artery which runs to the swimmeret muscles. The response indicates that tactile receptor reflexes bring about decreased haemolymph flow to the organs. Augmented swimmeret movements were always accompanied by an increased firing rate in the 5th lateral cardiac nerve. Artificial full protraction of swimmerets simultaneously induced excitation of the 5th lateral cardiac nerve and inhibition of the 1st lateral cardiac nerve. The excitation corresponds to an increase in haemolymph flow to the swimmerets, and the inhibition a decrease in haemolymph flow to walking-legs and viscera. Three kinds of mechanoproprioceptors which were activated by swimmeret movements were found. Two of the mechanoproprioceptors are located at the base of the basipodite. The other mechanoproprioceptor supplies processes to a nerve to the retractor muscles. Activation of three kinds of mechanoproprioceptors, induced by artificial swimmeret protraction, triggered lateral cardiac nerve reflex responses.Abbreviations LA lateral artery - LCN lateral cardiac nerve - RMN nerve to retractor muscles - StR stretch receptor     

Feeding mechanisms, and their variation in form, of some adult ground-beetles (Coleoptera: Caraboidea)

The structure of the mouthparts and foregut of some caraboid beetles has been correlated with their type of feeding mechanism. These may be adapted to fragmentary feeding, fluid feeding (where pre-oral digestion is important), or to mixed feeding (a large category which ranges from a mainly fluid to a mainly solid intake). Head structures concerned with feeding have been discussed in relation to these methods; they include the mandibles, maxillae, labrum-epipharynx and anterior foregut, proventriculus, labium-hypopharynx and the head floor. Different types of head floor were denned in relation to gular structure, in particular the presence or absence of the mid-gular apodeme. Convergent evolution of feeding mechanisms was noted amongst both fragmentary feeders and fluid feeders; in the latter group, sucking pumps have been evolved in the Carabitae, Scarites , Cicindelidae, Paussini and some other caraboids. It was suggested that head shape in caraboids may reflect locomotory adaptations more frequently than feeding adaptations.     

Genetic characterization of the lobster pathogen Aerococcus viridans var. homari by 16S rRNA gene sequence and RAPD

A combination of 16S rRNA sequencing and random amplified polymorphic DNA (RAPD) analysis was used to evaluate the genetic diversity within Aerococcus viridans var. homari, the causative agent of gaffkemia in lobsters. A collection of 7 A. viridans var. homari strains and 2 avirulent A. viridans-like cocci isolated from homarid lobsters harvested from different regions on the Atlantic Coast of North America were analyzed. The isolates are separated geographically and temporally between the years 1947 and 2000. Sequencing of 16S rRNA genes confirmed the inclusion of all 9 isolates in the monophyletic A. viridans clade (99.8 to 100% similarity). RAPD analysis revealed that the 9 A. viridans var. homari isolates could be separated into 2 distinct subtypes. Subtype 1 included the 7 pathogenic lobster isolates and constituted a homogeneous group regardless of their geographical, temporal or virulence differences. Subtype 2 contained the 2 avirulent A. viridans-like cocci that had distinct RAPD patterns and clustered separately with the non-marine A. viridans. RAPD analysis represented a useful method for determining molecular subtyping for the intraspecific classification and epidemiological investigations of A. viridans var. homari.     

Position and definition of the genus Paegniodes Eaton, 1881 based on redescription on the type species Paegniodes cupulatus (Eaton, 1871) (Ephemeroptera: Heptageniidae)

The genus Paegniodes Eaton, 1881 and its type species P. cupulatus (Eaton, 1871) have never been described in detail completely. In this article, all stages are described and photographed. Compared to other heptageniid genera, the adults of P. cupulatus have a more colourful body, smaller hindwings but larger titillators. The nymphs of this species have no setae or tubercles on the body and no emarginations on the head capsule. They have smaller lamellae of the first gills, a wider labrum with a median notch, mandibles without setae on outer margins, maxillae with a row of setae and scattered setae on the ventral surface, cerci with mesal setae, and a median filament with setae on both sides. Both imaginal and nymphal stages of the genus have unique characters, so the taxon Paegniodes is recognized at the rank of genus here. It appears closely related to Rhithrogena Eaton, 1881.     

中国颚毛(虫兆)属二新种(弹尾目,疣(虫兆)科)

记述了采白海南和浙江省的弹尾目疣[虫兆]科颚毛[虫兆]属Crossodonthina Yosii,2新种,海南颚毛yao C．hainana sp．nov．和天童颚毛yao C．tiantongshana sp．nov．。海南颚毛[虫兆]头部每侧有眼2个,弹器痕上有6根刚毛,非常容易与本属其它已知种类分开。天童颚毛[虫兆]与上海产的Crossodonthina tridentiens Yue＆Yin,1999相似,两者的主要区别是：新种的上颚有两条长的、羽毛状分支和具5齿的片状突起,且基部齿长而细;下颚的内颚叶端部及近基部各有1齿;新种腹部第5节有3＋3个疣状突起,而C．tridentiens有2＋2个疣状突起;新种的爪部内侧有2个小齿,1个大齿,C．tridentiens只有1大齿。模式标本保存于上海生命科学研究院,植物生理生态所昆虫标本馆。     

Comparison of isometric contractile properties of the tongue muscles in three species of frogs, Litoria caerulea, Dyscophus guinetti, and Bufo marinus.

Previous studies show that anurans feed in at least three different ways. Basal frogs have a broad tongue that shortens during protraction and emerges only a short distance from the mouth. Some frogs have long, narrow tongues that elongate dramatically due primarily to inertia from mouth opening, which is transferred to the tongue. A few species have a hydrostatic mechanism that produces tongue elongation during protraction. This functional diversity occurs among frogs that share the same two pairs of tongue muscles. Our study compares the isometric contractile properties of these tongue muscles among three frog species that represent each feeding mechanism. Nerves to the paired protractors and retractors were stimulated electrically in each species to record the force properties, contraction speeds, and fatigabilites of these muscles. Few differences were found in the isometric contractile properties of tongue muscles, and the greatest differences were found in the retractors, not the protractors. We propose that the unique arrangement of the tongue muscles in frogs results in a retractor that may also be coactivated with the protractor in order to produce normal tongue protraction. Inertial effects from body, head, and jaw movements, along with clear differences that we found in passive resistance of the tongues to elongation, may explain much of the behavioral variation in tongue use among species.     

Anatomy and Ultrastructure of Ventral Pharyngeal Organs and their Phylogenetic Importance in Polychaeta (Annelida). IV. The Pharynx and Jaws of the Dorvilleidae

An anatomical and ultrastructural investigation of the ventral pharyngeal organ, jaws and replacement of jaws was carried out in Ophryotrocha gracilis and Protodorvillea kefersteini (Dorvilleidae). The pharynx exhibits the following features: jaw apparatus present, consisting of paired mandibles and rows of maxillary plates, the latter are fused to form a single piece; cuticular jaws electron-dense, in P. kefersteini with collagen fibres; muscle bulbus solid, composed of muscle cells only; parallel running myofilaments, centrally located mitochondria and nuclei, bulbus epithelium containing the mandibles and gland cells, maxillary plates lying on folds corresponding to a tongue-like organ, connected with mandibles by longitudinal investing muscles; numerous gland cells not united to distinct salivary glands. Development of jaw replacements occurs in epithelial cavities beside the functional maxillae. Shape of maxillary plates is preformed by microvilli carrying cell processes. Maxilloblasts change their shape during the development. Synapomorphic structures occurring in ventral pharyngeal organs of other species outside the Eunicea are not present and even the closely related Dinophilidae exhibit a completely different pharyngeal organ. Therefore, convergent evolution of these organs is the most probable explanation. These findings do not agree with the hypothesis of the homology of the ventral pharyngeal organs in the Polychaeta.     

Sensory receptors associated with the stylets and cibarium of the rice brown planthopper,Nilapavarta lugens

Summary The stylets of Nilapavarta lugens consist of two maxillae that interlock to form separate food and salivary ducts partially surrounded by two mandibles. The ultrastructure of the sensory innervation of the stylets is described. Each maxilla possesses five neurones which extend to the tip of the stylet. The mandibles also contain five neurones, four of which are paired. The paired neurones comprise a shorter dendrite extending part of the way along the stylet and a longer one extending to the tip. The possible functions of these neurones are discussed. Gustatory receptors are located in the small passageway leading from the food duct to the cibarium. The receptors are in two distinct groups on the epipharyngeal side and one group on the hypopharyngeal side of the food canal. Two to five neurones innervate each receptor which connects to the food canal via a small pore.     

Cellular expression of gut chitinase mRNA in the gastrointestinal tract of mice and chickens.

Recently, the second mammalian chitinase, designated acidic mammalian chitinase (AMCase), has been identified in human, mouse, and cow. In contrast to the earlier identified macrophage-derived chitinase (chitotriosidase), this chitinase is richly expressed in the gastrointestinal (GI) tract, suggesting its role in digestion of chitin-containing foods as well as defense against chitin-coated microorganisms and parasites. This in situ hybridization study first revealed cellular localization of the gut-type chitinase in the mouse and chicken. In adult mice, the parotid gland, von Ebner's gland, and gastric chief cells, all of which are exocrine cells of the serous type, expressed the gut chitinase mRNA. In the chicken, oxyntico-peptic cells in glandular stomach (proventriculus) and hepatocytes expressed the chitinase mRNA. Because cattle produce the gut chitinase (chitin-binding protein b04) only in the liver, the gut chitinases in mammals and birds have three major sources of production, i.e., the salivary gland, stomach, and liver. During ontogenetic development, the expression level in the parotid gland and stomach of mice increased to the adult level before weaning, whereas in the stomach of chickens intense signals were detectable in embryos from incubation day 7.     

The burrowing of Priapulus caudatus

An account is given of the way in which Priapulus caudatus burrows in the muddy sea-bed in which it lives. Three phases are distinguishable in the muscular activity which is responsible for locomotion. During the first phase the animal is able to feed and defaecate, during the second the proboscis becomes invaginated, and during the third the animal moves forward. The power for locomotion is provided by contraction of the longitudinal and circular muscles of the body wall, not, as has been suggested previously, by the retractor muscles of the praesoma. Invagination of the proboscis is apparently stimulated by the arrival of a wave of contraction in the body wall musculature, propagated from the trunk.
In general the animal burrows in a way common for soft-bodied animals; the anterior and posterior extremities acting in turn as "terminal" and "penetration" anchors in the substratum. The muscular activities of the larva are limited by the presence of a lorica which encases the trunk, and the animal's powers of movement at this stage are very restricted.     

Morphology and distribution of antennular setae of scyllarid lobsters (Scyllarides aequinoctialis, S. latus, and S. nodifer) with comments on their possible function

Abstract. Lateral flagella of the antennules of scyllarid lobsters were examined for setal morphology and distribution via scanning electron microscopy. Setal distribution patterns were mapped directly for 3 regions of the antennule ( base, tuft , and tip ) and analyzed for differences: (1) between left and right antennules, (2) between males and females within a species, and (3) among species by comparing counts of setae per annulus in the ventral tuft region only. Six types of antennular setae were identified based on their external morphology: aesthetases, simple, modified simple, asymmetric, hemi-plumose, and toothbrush setae. These different types were organized in a clear pattern over the ventral and dorsal surfaces of the lateral flagella of the antennule. Aesthetase, asymmetric, modified simple, and hemi-plumose setae were found only on annuli in the tuft region between the distal and proximal ends of the flagellum. Simple setae were found on all annuli of all regions of the antennule, and toothbrush setae were mainly concentrated on all annuli of the base region and on proximal annuli of the tuft region . All species of scyllarids examined had the same general pattern of setal distribution and no differences were found between left and right, or male and female antennules. Similar setae located on the lateral antennules of species from the families Nephrophidae and Palinuridae (clawed and spiny lobsters) have been previously described as chemo- and/or mechanoreceptive for use in distance chemoreception (i.e., detection and orientation to olfactory stimuli). Based on work on clawed and spiny lobsters, we predict that the aesthetases on slipper lobsters have a chemoreceptive function and that simple and toothbrush setae may have a bimodal chemo- and mechanoreceptive function.     

Classification of Homarus americanus hemocytes and the use of differential hemocyte counts in lobsters infected with Aerococcus viridans var. homari (Gaffkemia)

Hemocytes of the American lobster (Homarus americanus H. Milne Edwards) were classified after examination of Wright-Giemsa stained cytocentrifuge preparations by brightfield light microscopy. Eleven hemocyte types were identified using morphologic criteria. The classification system was then used to monitor changes in the differential hemocyte count (DHC) of lobsters infected with the Gram positive coccus Aerococcus viridans var. homari, etiologic agent of gaffkemia. The appearance of less mature hemocytes in the DHCs of lobsters in the late stages of infection was similar to the 'left shift' of vertebrate inflammation. Results from this study suggest that DHCs can be used to assess and characterize inflammation in H. americanus and possibly other crustaceans.     

How do ants stick out their tongues?

The mouthparts are very important tools for almost any task performed by ants. In particular, the labiomaxillary complex is essential for food intake. In the present study we investigated the anatomical design of the labiomaxillary complex in various ant species, focusing on movement mechanisms. Six labial and six maxillary muscles with different functions control the several joints and ensure the proper performance of the labiomaxillary complex. According to our measurements of sarcomere lengths, muscle fiber lengths and diameters, and the relative muscle volumes, the labial and maxillary muscles feature rather slow than fast muscle characteristics and do not seem to be specialized for specific tasks. Since glossa protractor muscles are absent, the protraction of the glossa, the distal end of the labium, is a nonmuscular movement. By histological measurements of hemolymph volumes we could exclude a pressure-driven mechanism. Additional experiments showed that, upon relaxation of the glossa retractor muscles, the glossa protracts elastically. This elastic mechanism possibly sets an upper limit to licking frequency, thus influencing food intake rates and ultimately foraging behavior. In contrast to many other elastic mechanisms among arthropods, glossa protraction in ants is based on a mechanism where elasticity works as an actual antagonist to muscles. We compared the design of the labiomaxillary complex of ants with that of the honeybee and suggest an elastic mechanism for glossa protraction in honeybees as well.     

Presomal morphology and development of Prosthorhynchus formosus,Prosthenorchis elegans,and Moniliformis dubius (Acanthocephala)

Larvae removed at one-day intervals from laboratory infected intermediate hosts provided material for a comparative study of presomal development in Prosthorhynchus formosus (Van Cleave, '18) Travassos, '26, Prosthenorchis elegans (Diesing, 1851) Travassos, '15, and Moniliformis dubius Meyer, '33. Acanthellae begin development soon after entering intermediate hosts' hemocoels, and by the 18th day all three species possess three nuclear masses representing primordia of the proboscis, proboscis receptacle and ganglion, and trunk musculature and genitalia. Presomal development of P. formosus and P. elegans results in structures concurring with morphology of other adult palaeacanthocephalans and archiacanthocephalans. Development of M. dubius, however, differs from that of other archiacanthocephalans in that the muscular receptacle wall lines the entire surface of the nonmuscular sheath, failing to form a ventral cleft characteristic of other archiacanthocephalans. Unlike receptacle protrusor muscles of other archiacanthocephalan species, those of M. dubius spiral around the receptacle as they extend posteriad to attach individually to a pouchlike, muscular thickening at the receptacle's base. These protrusor muscles are distinct from the receptacle wall, as attested by their development alongside neck retractor muscles, not from the receptacle primordium, and the manner in which they are left to trail behind the receptacle when it is drawn anteriorly into the proboscis during larval development. The proboscis receptacle of M. dubius should not be thought of as being double-walled, as envisioned by previous workers.     

THE ADDUCTOR AND RETRACTOR MUSCLES OF THE VELIGER OF PECTEN MAXIMUS (L.) (BIVALVIA)

In Pecten maximus (L.), retractor and adductor muscles becomefunctional in the early veliger larva. The twelve-day-old veligerhas four pairs of velar retractors, three pairs of retractorsattached to the posterior body wall and an anterior adductor.The pediveliger has in addition, pedal retractor muscles anda posterior adductor. The retractors consist of striated muscle:the adductors have both smooth and striated portions. The retractorsattach near the hinge, branch to a greater or lesser extent,then attach to specific areas of the velum, posterior body walland foot. Some features of the branching and of the dispositionof points of attachment form a pattern which exhibits mirrorsymmetry about the plane between the two shell valves. Thispattern is characteristic of the species. It is deduced thatretraction and protraction of the velum result from co-ordinatedsequences of muscle contractions. ^*Present address: Forest Products Research Centre, P.O. Box1358, Boroko, Papua New Guinea. (Received 15 June 1984;     

Ultrastructural differentiation of glandular stomach (proventriculus) in chick embryo

Cytochemical characterization of mucosubstances of chick glanular stomach (proventriculus) changes from 15 days of development to postnatal and adult stages was studied. To corroborate these data cytochemical, ultrastructural and ultracytochemical study of chick embryo proventriculus from 7 to 20 days of development was performed. At the 7th day several layers of undifferentiated cells formed an epithelium which covered the walls of the glandular stomach. Mocosubstances were not found. Between the 9th and 5th day a single layer of cylindrical cells was encountered forming invaginations which originated deep glands. Three types of cells were separated from the above mentioned layer, dark, clear and undifferentiated. The dark cells had organelles which are involved in protein synthesis and the clear ones were rich in mitochondria. Argentaffine cells appeared at 15th day instead mucosubstances formed a thin coat on the epithelium at 9th day which increased at the end of development in the apical cytoplasm and gland cells. These observations demonstrate that proventriculus of chick embryo has ultrastructurally differentiated cells involved with enzymatic and hydrochloric acid secretion after the 9th day. These progressive events are correlated with the digestion process of yolk during embryogenesis. At the end of development the proventriculus has completely organized the glandular layer.     

External microstructure of the ambrosia beetle Platypus koryoensis (Coleoptera: Curculionidae: Platypodinae)

Platypus koryoensis is a minute ambrosia beetle found in forests. It can cause significant economic damage to oak trees. Recently in Korea, it has been reported as a major pest of oak trees, because it causes sooty mold of oak by introducing the pathogenic fungus Raffaelea sp. In this paper, we demonstrate the fine structural aspects of the external body of the ambrosia beetle using field emission scanning electron microscopy, as a part of basic research into this pest so that strategies for its control might be developed. This beetle has a sensory system well developed to respond to both visual and chemical stimuli. Both sexes have a pair of faceted compound eyes and a pair of knobbed antennae, but simple eyes are absent. The mouthparts on its distinct snouts are effective devices for penetration and for boring holes. The mouthparts consist of the labrum, a pair of mandibles, a pair of maxillae and the labium. Both the maxillary and the labial palpi have the function of directing the food to the mouth and holding it while the mandibles chew the food. The distal ends of these palpi are flattened and have shovel‐like setae. The thorax has a particularly hard exoskeleton and hard elytra, including powerful muscles that operate both the wings and the legs. The legs are multi‐segmented and have a strong femur and tibia, including one pair of claws on the end of each tarsal segment. Characteristically, both male and female beetles have mycangial cavities for storing spores and other microorganisms, but only females have three pairs of large depressions on their dorsal thorax.     

Systematic characters of some polychaetes (Annelida) at the level of the chemical composition of the jaws

The mandibles and maxillae of the buccal ventral organ of 2 species of Eunicidae (Marphysa sanguinea and Eunice torquata) are highly calcified, in contrast to the jaws of 4 species of other families of ‘errant’ predacious Polychaetes (Nereidae, Nephthyidae, Aphroditidae and Glyceridae) with axial proboscis. The amino acid composition of the structural proteins of these buccal pieces is also different in the two groups. The structural proteins of the jaws of Glycera convoluta (Glyceridae) are essentially made up of glycine and histidine (up to 86 residues per 100 residues). These chemical characters confirm the phyletic relationships proposed by Dales.¹     

The suction mechanism of the pipid frog,Pipa pipa (Linnaeus, 1758)

Most suction‐feeding, aquatic vertebrates create suction by rapidly enlarging the oral cavity and pharynx. Forceful enlargement of the pharynx is powered by longitudinal muscles that retract skeletal elements of the hyoid, more caudal branchial arches, and, in many fish, the pectoral girdle. This arrangement was thought to characterize all suction‐feeding vertebrates. However, it does not exist in the permanently aquatic, tongueless Pipa pipa , an Amazonian frog that can catch fish. Correlating high‐speed (250 and 500 fps) video records with anatomical analysis and functional tests shows that fundamental features of tetrapod body design are altered to allow P. pipa to suction‐feed. In P. pipa , the hyoid apparatus is not connected to the skull and is enclosed by the pectoral girdle. The major retractor of the hyoid apparatus arises not from the pectoral girdle but from the femur, which lies largely within the soft tissue boundaries of the trunk. Retraction of the hyoid is coupled with expansion of the anterior trunk, which occurs when the hypertrophied ventral pectoral elements are depressed and the urostyle and sacral vertebra are protracted and slide forward on the pelvic girdle, thereby elongating the entire trunk. We suggest that a single, robust pair of muscles adduct the cleithra to depress the ventral pectoral elements with force, while modified tail muscles slide the axial skeleton cranially on the pelvic girdle. Combined hyoid retraction, axial protraction, and pectoral depression expand the buccopharyngeal cavity to a volume potentially equal to that of the entire resting body of the frog. Pipa may be the only tetrapod vertebrate clade that enlarges its entire trunk during suction‐feeding.     

Functional morphology of the mouthparts and associated structures of Pagurus rubricatus (Crustacea: Decapoda: Anomura) with special reference to feeding and grooming

Summary Pagurus rubricatus is predatory, detrivorous, macrophagous, and to a small degree, a suspension feeder. The crab searches for small invertebrates by digging shallow pits in the sediment. During this process it feeds on detritus obtained either directly from the sediment or scoured off gravel granules. Particles trapped by the dense setation of the 2nd and 3rd maxillipeds are brushed off and ingested.The distribution of the various types of setae on the mouthparts is mapped and structure of the mouthparts and their setae is correlated with function. Sediment collected by the pereiopods is brushed off by the endopodites of the 3rd maxillipeds and transferred to the inner mouthparts by the endopodites of the 2nd maxillipeds. The basipodites of the 1st maxillae form a filter screen through which particles of suitable size are pushed by the 2nd maxillae. Rejected particles are discarded by the exhalant stream via the currents generated by the exopodites of the maxillipeds. Specialized setae on the 2nd maxillae scour detritus from the surface of gravel granules applied to these appendages by the 2nd and 3rd maxillipeds. Interlocking setae from different appendages form a number of screens the main function of which is to retain material in the buccal region. The exopodite and endopodite of the 1st maxilliped and the endopodites of the 1st and 2nd maxillipeds form a channel which funnels the exhalant respiratory current away from the crab. The main grooming appendages are the endopodites of the 3rd maxillipeds, however, most of the other mouthparts have a self-cleaning function.