Larval Organs Research Articles

The Oral Papilla of the Lancelet Larva (Branchiostoma lanceolatum) (Cephalochordata)

AbstractThe oral papilla is a prominent larval organ in the lancelet, which develops early during ontogenesis and disappears completely at metamorphosis. Electron microscopic studies indicated that the prevailing theories of its function are unlikely. Its cells lack the cytological characteristics of sensory or mucus producing cells, and the organ is not equipped with a tuft of flagella. It was not possible to reveal the function of the papilla, but its cells seem to be involved in a pronounced substance transport through the basal cell membrane as well as in the cytoplasm. Apical specializations indicate exo‐ or endocytotic activity and vesicles imply some exchange also between papilla cells and the sea water.

Larval hemolymph feeding in the ant Leptanilla japonica by use of a specialized duct organ, the ?larval hemolymph tap? (Hymenoptera: Formicidae)

The larvae of the migratory Japanese ant Leptanilla japonica Baroni Urbani have a specialized duct organ on each side of the 4th abdominal segment. Behavioral and histological studies have shown that the adult ants are able to imbibe hemolymph directly from the larval body cavity through these organs, each of which is referred to here as a “larval hemolymph tap.” Laboratory observations further confirm that larval hemolymph feeding (LHF) is the sole source of nutrient for the queens. L. japonica is cyclical in its brood production. All larvae in a colony develop in concert, and when they are mature, the queen performs much active LHF on them. Nourished in this way, she achieves full physogastry within a period of only a few days and then lays a batch of 100–200 eggs. LHF thus facilitates synchronization of brood maturation and concentrated production of eggs by the queen. The larval hemolymph tap has probably evolved de novo in Leptanilla, in relation to cyclical brood production by species with small colony populations. Obviously, the function of this larval organ is non-selfish, contributing to overall colony-level functioning. The larvae of Leptanilla are thus properly qualified as a distinct class of caste in ant societies.

The larval ant-organs of Thisbe irenea (Lepidoptera: Riodinidae) and their effects upon attending ants

Observations and experiments are presented on the use of larval ant-organs by the riodinid butterfly Thisbe irenea with emphasis on their function in myrmecophily. The results indicate that each ant organ plays a distinct role in larval-ant association and that all influence the behaviour of attending ants. Interpretations of the roles that lycaenid larval organs play in ant associations are evaluated and discussed in light of myrmecophilous riodinids. Finally, an ‘enticement and binding’ process, involving the concerted use of the larval organs, is proposed as the behavioural mechanism that 7. irenea and other riodinid larvae use to secure the attentions of individual ants for extended periods of time.

Immunohistochemical demonstration of calbindin-D 28K (CABP28K) in the spinal cord motoneurons of teleost fish.

The distribution and localization of the calcium-binding protein, calbindin-D 28K (CaBP28K), in the spinal cord motoneurons of larvae of the teleost fish, Apteronotus leptorhynchus (Gymnotidae) and Pollimyrus isidori (Mormyridae), and in the adult goldfish, Carassius auratus (Cyprinidae), were determined by means of immunohistochemistry. Sections of whole larvae and goldfish spinal cord were reacted with a polyclonal antibody to rat renal CaBP28K. CaBP28K was located by the PAP technique (Sternberger). It was found in the soma, dendrites, axons and axon terminals of spinal motoneurons but not in those of electromotoneurons of Apteronotus leptorhynchus, whereas it occurred in both motoneurons and electromotoneurons of the larval electric organ of Pollimyrus isidori. In these species CaBP28K was also present in the electromotoneuron axon terminals that make synaptic contacts with the pedicles of the electrocytes. In adult Carassius auratus, CaBP28K was found in the soma, dendrites and axons of certain spinal motoneurons. The results indicate that, in teleosts, the motoneurons containing CaBP28K may represent a well-defined population within the spinal cord; the role of this protein in these cells remains to be determined.

Organization of the Nervous System and Sensory Organs in the Larva of the Marine Bryozoan Bowerbankia gracilis (Ctenostomata: Vesiculariidae): Functional Significance of the Apical Disc and Pyriform Organ

AbstractThe organization of the nervous system and the histology and ultrastructure of the apical disc and the pyriform organ have been investigated by serial sections with light and electron microscopy for the larva of the vesiculariid ctenostome bryozoan Bowerbankia gracilis Leidy 1855. The nervous system consists of four major internal components: (1) a median‐anterior nerve nodule; (2) an equatorial, subcoronal nerve ring; (3) paired aboral nerve cords; (4) paired antero‐lateral nerve tracts. The nervous system is associated with the ciliated larval surface at the apical disc, the pyriform organ, the corona and the intercoronal cells. The paired aboral nerve cords extend from the apical disc to the nerve nodule, which gives rise to the paired antero‐lateral nerve tracts to the pyriform organ and to paired lateral tracts that form the equatorial nerve ring. Ultrastructural evidence is provided for the designation of primary sensory cells in the neural plate of the apical disc and in the juxtapapillary regions of the pyriform organ. Efferent synapses are described between the equatorial nerve ring and the overlying coronal cells, which constitute the primary locomotory organ of the larva. The repertoire of potential functions of the apical disc and pyriform organ are discussed. It is concluded that the apical disc and pyriform organ constitute larval sensory organs involved in orientation and substrate selection, respectively. Their association with the major effector organs of the larva (the corona and the musculature) via the nervous system supports this interpretation.

Effect of methoprene on growth profile of larval organs of the silkworm, Bombyx mori L.

Effect of methoprene on growth profile of larval organs of the silkworm, Bombyx mori L.

Bryozoan larvae as mosaics of multifunctional ciliary fields: Ultrastructure of the sensory organs of Bugula solonifera (Cheilostomata: Cellularioidea).

The ultrastructure of ciliated sensory and effector organs has been examined by light microscopy and by scanning and transmission electron microscopy in larvae of the cellularioid cheilostome, Bugula stolonifera. The larval surface is formed by a mosaic of ciliary fields, each distinctive in organization and function. The most extensive ciliary field consists of the motile cilia of the corona, which collectively constitute the primary larval locomotory organ and form most of the larval surface. The corona is innervated basally by a nerve ring that circumscribes the larval equator. A circular field of immotile shorter cilia at the aboral pole arise from bands of radial cells in the apical disc. The radial ciliated cells form chemical synapses with underlying nerves of the paired aboral nerve cords, which extend to an equatorial nerve plexus on the median anterior side of the larva, beneath the pyriform organ. The pyriform organ is a complex of ciliated and glandular regions aligned along the anterior midline of the larva. It consists of, in aboral to oral sequence: the superior glandular field, the vibratile plume, the inferior glandular field, and the ciliated cleft. The vibratile plume is distinctive from the surrounding ciliation by its length and pattern of beating. It consists of four bundles of cilia approximately 64 μm long that beat rhythmically in synchrony into the ciliated cleft. Each bundle of cilia arises from a single cell which is further distinguished by apical pits of stout microvilli. The glandular fields and the vibratile plume are bordered by a variety of previously undescribed ciliated cells, longitudinal myoepithelial cells, and a pair of antero-medial eyespots. Another type of ciliated sensory cell is located between cornal cells. These intercoronal cells form synapses directly with the adjacent coronal cells. On the basis of these ultrastructural observations, the radial ciliated cells of the apical disc and the intercoronal cells are classified as primary sensory cells with different motor pathways. The radial ciliated cells are associated with the various effector organs of the larva via the nervous system. The intercoronal cells may combine sensory and motor functions by synapsing directly with the larval locomotory organ.

Effects of thyroxine-driven precocious metamorphosis on maturation of adult-type allograft rejection responses in early thyroidectomized frogs

In contrast to the adult pattern of allograft reactivity, larval South African clawed frogs (Xenopus) either become tolerant of adult major histocompatibility complex (MHC) disparate skin grafts or reject them slowly. Larvae fail to reject grafts that are incompatible at minor histocompatibility (H) loci (MHC-identical); rather, they become immunologically tolerant. We report here that early thyroidectomized (thyroidx) larvae, forced to metamorphose precociously on a regimen of thyroxine (T4) treatment, showed larva-like responses in that their ability to reject skin allografts that differed by minor H loci or one MHC haplotype was significantly impaired relative to age-matched intact postmetamorphic controls. During the normal ontogeny of Xenopus, lymphocyte numbers increase in larval life, decrease during metamorphosis, and increase to adult levels at 6-12 months of age. Thyroidectomy and a low-dose regimen of thyroxine treatment limited the number of lymphocytes that developed in larval organs and very dramatically reduced those populations below control levels during metamorphosis. Because these changes were stage-dependent rather than age-dependent, the second wave of lymphopoiesis in thyroidx frogs treated with low T4 may occur out of synchrony with the expression of Class I MHC antigens. Impaired allograft rejection, therefore, may reflect the absence of a population of cells that can effectively recognize minor H alloantigens and/or self and allo Class I antigens.

The ecology, discharge diversity and predatory behaviour of gymnotiforme electric fish in the coastal streams of French Guiana

1. A survey of the species distribution, discharge characteristics, ecology and behaviour of South American Gymnotiforme electric fish was carried out during two field trips to sites in the vicinity of Kourou, French Guiana, in 1983 and 1985. 2. Measurements of water conditions, collected over a twelve month period, highlight the strong ecological pressure on species exploiting the rapidly fluctuating and often temporary coastal streams. Adaptation of the reproductive cycle to the rainy seasons is particularly marked and the possible zeitgebers are considered. Given the almost invariant water conductivity, its suggested use as an environmental trigger is rejected in favour of acoustic or mechanical cues. 3. The two main study areas were inhabited principally by pulse gymnotoids of the genera Gymnotus and Hypopomus. A new Hypopomus species was discovered as well as specimens of G. pantherinus, previously undescribed in French Guiana. Larvae of H. beevei were found prior to the start of the 1985 rainy season. Developmental data for this species are presented which support the view that, as in other weakly electric gymnotoids, a primitive larval electric organ probably precedes the adult structure. The larval discharge also strongly resembles that of the adult electric eel, lending weight to published theories of an Electrophorus-like ancestor to the wekly electric fish. 4. The predatory behaviour of the strongly electric eel was recorded in detail. The field results indicated that this species preyed on weakly electric fish whose responses to the foraging eel are also reported. The probable use of electrical cues by hunting eels was further investigated in a laboratory experiment in which predatory responses were compared in the presence of non-electric and electric live prey, and models mimicking electric prey. It is concluded that electrical cues are probably of paramount importance in the eel's normal prey capture behaviour.

Metamorphosis of the marine bryozoan Membranipora membranacea: An ultrastructural study of rapid morphogenetic movements.

The colonial marine bryozoan Membranipora membranacea produces a planktotrophic cyphonautes larva that is encased by a triangular bivalved shell. Following a relatively long free-swimming phase, the cyphonautes larva settles and undergoes a dramatic metamorphosis to become the sessile progenitor of the colony, referred to as the ancestrula. This paper examines the initial morphogenetic movements of metamorphosis that transform the cyphonautes larva into an incipient ancestrula. At the onset of metamorphosis, contractions of the striated median muscles situated along the anterior and posterior margins of the larva cause a retraction of the larval apical organ and a centripetal movement of the anterior and posterior ends of the larva. Concurrently, the ciliated corona at the base of the larva is pulled within the shell by contractions of the striated lateral muscles. As the larva assumes a more spherical shape, the posterior margins of the shell are spread apart, and the internal sac is everted. Eversion of the sac is apparently achieved by contractions of the lateral muscles that cause a buckling of the shell in the apical-basal direction. The neck region of the everted sac secretes adhesive granules that attach the larva to the substratum. Subsequently, contractions of the nonstriated sac muscles fold the valves of the shell over each other and draw the larva toward the substratum. The initial events of metamorphosis that culminate in the attachment and flattening of the larva are completed in 10-15 seconds. In the subsequent few minutes, the lateral edges of the everted sac fuse with the neighboring margins of the aboral epithelium underlying the shell and thus form the fully sealed body wall of the incipient ancestrula.

The cyphonautes larva of the marine bryozoan Membranipora membranacea. I. General morphology, body wall, and gut

The cyphonautes larva of Membranipora membranacea (phylum Bryozoa, order Cheilostomata) is a laterally compressed, planktotrophic larva covered by a triangular, bivalved shell. In this paper, the general morphology of the larva and the cytology of the body wall and gut are examined by light and electron microscopy. The outer part of the body wall underlying the shell consists of an essentially nonciliated layer, called the aboral epithelium. At the larval apex, the aboral epithelium forms a knob-shaped apical organ. The apical organ contains putative sensory cells, a basal nerve plexus, and a group of undifferentiated epithelial cells that probably corresponds to a blastema. The body wall at the base of the larva constitutes the larval locomotory organ or corona. The corona consists of two rows of multiciliated cells, which are flanked by myoepithelial cells and monociliated cells. A large mantle cavity, referred to as the vestibule, occupies the central region of the larva. The vestibule is partially divided into an anterior inhalant chamber and a posterior exhalant chamber by two ciliary ridges that run along the sides of the mantle cavity. At the base of the larva, the inhalant chamber is surrounded by a horseshoe-shaped flap of tissue, called the velum. Apically, the inhalant chamber forms a densely ciliated preoral funnel. Food particles filtered by the ciliary ridges are conveyed to the larval mouth by cilia in the preoral funnel. The mouth in turn leads into a tripartite gut consisting of an esophagus, stomach, and intestine. Two types of ciliated lining cells occur in the esophagus and stomach. The intestine appears to be lined by nonciliated epithelial cells and empties into the exhalant chamber by way of an anus. Morphological features of the cyphonautes larva are compared with those described for other bryozoan larvae in an attempt to define homologous structures among the various larvae of bryozoans.

Metamorphosis of identified neurons innervating thoracic neurohemal organs in the blowfly: transformation of cholecystokininlike immunoreactive neurons.

With antisera to gastrin/cholecystokinin, we studied the postembryonic development of neurons in the thoracic ganglia of the blowfly Calliphora erythrocephala. There are some changes in the population of thoracico-abdominal neurons displaying gastrin/CCK-like immunoreactivity (CCKLI): some CCKLI neurons cannot be found after pupariation; other neurons become immunoreactive during metamorphosis. Six large thoracic CCKLI neurons could, however, be followed through metamorphosis. These CCKLI neurons innervate neuropil in thoracic ganglia and segmental neurohemal organs in the larva. In the adult insect the same neurons innervate many regions of thoracic neuropil and extensive neurohemal areas dorsally in the fused thoracico-abdominal ganglia. The immunoreactive terminals are located in the neural sheath, and electron microscopy shows that only an extracellular basal lamina separates them from the circulating hemolymph. On the basis of the location of their terminals, it can be suggested that the six CCKLI neurons have functions as neurosecretory cells both in the larva and in the adult. In both developmental stages the neurons can interact with large portions of the thoracic nervous system and release bioactive substance into the circulation. A CCK-like substance may be used both as a transmitter/neuromodulator and as a neurohormone by the same neuron. The larval neurohemal organs are described here for the first time. They show characteristics of thoracic perisympathetic organs known to exist in more primitive insects. The adult neurohemal regions on the other hand are typical of higher insects. Since the neurohemal areas are continuously (during development) innervated by the six large CCKLI neurons, we conclude that the larval neurohemal organs metamorphose into the adult neurohemal area in the neural sheath.

LOCALIZATION OF A DROSOPHILA EYE PROTEIN WHICH IS PHOSPHORYLATED AFTER LIGHT STIMULATION

In fruit fly, Drosophila melanogaster, three eye proteins are known to be phosphorylated by light stimulation (8, 9). Among them, 49 K protein is most abundant. Matsumoto et al. (8, 9) suggested their possible involvement in the visual procasses. In this paper, we describe its cellular localization revealed by immunohistological methods. The protein is localized in all the visual receptor cells including retinular cells (R1-R8) of the adult compound eye, adult ocelli and larval photoreceptor organ. It also exists in their axons. The antigen is shown to be enriched in microvillous rhabdomere and multivesicular cells suggests that it plays an important role in the processes following photoreception and transduction.

Analysis of the promoter of the ninaE opsin gene in Drosophila melanogaster.

We have analyzed the cis-acting regulatory sequences of the ninaE gene. This gene encodes the major Drosophila melanogaster opsin, the protein component of the primary chromophore of photo-receptor cells R1-R6 of the adult eye. DNA fragments containing the start point of transcription of the ninaE gene were fused to either the Escherichia coli chloramphenicol acetyltransferase or lacZ (beta-galactosidase) gene and introduced into the Drosophila germline by P-element-mediated transformation. Expression of the E. coli genes was then used to assay the ability of various sequences from the ninaE gene to confer the ninaE pattern of expression. Fragments containing between 2.8 kb and 215 bp of the sequences upstream of the start of transcription plus the first 67 bp of the untranslated leader were able to direct nearly wild-type expression. We have identified three separable control regions in the ninaE promoter. The first, which has the properties of an enhancer element, is located between nucleotides -501 and -219. The removal of this sequence had little effect on promoter function; this sequence appears to be redundant. However, it appears to be able to substitute for the second control region which is located between nucleotides -215 and -162, and which also affects the level of output from this promoter. Removal of these two control regions resulted in a 30-fold decrease in expression; however tissue specificity was not affected. The third control region, located downstream from nucleotide -120, appears to be absolutely necessary for promoter function in the absence of the first two regulatory sequences. Examination of larvae containing fusion genes expressing beta-galactosidase suggests that the ninaE gene is also expressed in a subset of cells in the larval photoreceptor organ.

Postembryonic development of the parasitic amphipodHyperia galba

Hyperia galba Montagu is associated with gelatinous zooplankton as are many species of the Hyperiidea. The hosts preferred in the European seas are the large scyphomedusaeAurelia aurita, Chrysaora hysoscella, Rhizostoma pulmo, Cyanea capillata andCyanea lamarckii, which harbour the first developmental stages. The anamorphic development produces young that are incapable of swimming at the time of hatching. They are characterized by an embryonic abdomen without extremities and external segmentation; the eyes are not completely developed and the mouth is primitive lacking bristles, molar and incisor. The postembryonic development, described in detail, is subdivided into two phases: the pantochelis phase and the protopleon phase; the former comprises only one stage; the latter can be subdivided into four stages. In the course of postnatal development the larval organs are reduced and characters typical of the adult are gradually differentiated.H. galba plays an important role as obligatory endoparasite of scyphomedusae at least during the first stages of development; without a host this amphipod cannot survive, neither benthically nor in the plankton. The transition from life in the female's marsupium to endoparasitism in the jellyfish generally occurs during stage of the postembryonic development which is the first stage of the protopleon phase. The specific adaptations of its reproductive biology to a parasitic mode of life such as moult inhibition under starvation, development of larval organs and the behavioural patterns of the females as well as the young are described. Further, the influence of external factors such as temperature and food supply on the course of development is examined.

Chromosome structure in four wild-type polytene tissues of Drosophila melanogaster. The 87A and 87C heat shock loci are induced unequally in the midgut in a manner dependent on growth temperature.

A systematic screen of wild-type Drosophila melanogaster larval organs has revealed three tissues besides the salivary gland with suitable polyteny for detailed cytogenetic analysis: the prothoracic gland, hindgut, and middle midgut. Chromosome banding patterns are very similar between tissues, but puffing patterns show considerable differences. In intact nuclei, oblique substructural elements can sometimes be detected in bands from some of the tissues. As a way of exploiting these newly characterized chromosomes, the heat shock puff response in midgut cells has been studied in detail. The puffing pattern is very similar to that in salivary glands, but an unexpected difference is found in the relative activity of the 87A7 and 87C1 loci, which contain the hsp70 genes. When larvae are raised at 16 degrees C, heat shocks ranging from 10 to 60 min induce only a weak midgut puff at 87A7 that is much smaller than that at 87C1, in contrast to other tissues where both are strongly induced. In pulse-labeled nuclei, an approximately five fold difference in transcriptional activity at the two loci is observed. However, when larvae are raised at 25 degrees C, the converse is found: the 87A7 puff is large, and little or no puffing is detectable at 87C1. Thus, in the midgut, heat shock induced puffing at these two loci is inversely modulated by a mechanism dependent on growth temperature.

Nucleic acid changes in the whole body of the flour moth, Ephestiua kuehniella, During metamorphosis

DNA content in the whole body of Ephestia kuehniella remained almost unchanged for the first 2–5 days after the larval-pupal ecdysis and then rose continuously throughout subsequent development until day 7 (pharate adult). After emergence the content of DNA reached a maximum. Essentially the same pattern was observed in both sexes. Although some differences were observed between sexes, changing pattern of RNA content in the whole body during metamorphosis can be divided into three phases. The content of RNA showed the U-shaped pattern throughout the course of life cycle when graphed against histolysis of larval organs and histogenesis of adult organs. Once the adult tissues were formed and emergence accomplished, the amount of RNA decreased in both sexes. The sexual difference in changing pattern of RNA/ DNA ratio in the whole body was discernible and reached a maximum level at 5-day pupa (males) and at 8-day pupa (females) and to the lowest level in the adult stage in both sexes.

The larval crustacean dorsal organ and its relationship to the trilobite median tubercle

In the dorsal median anterior region of the head, the larvae of decapod Crustacea possess a discrete organ: a glandular-sensory complex which is not present in post-larval juvenile forms. Its external topography reveals the presence of one or two central pores (Brachyura, Anomura) or a poreless central area (Macrura) surrounded by four equidistant plate-pits which contain a central pimple or ‘nipple’. The Macrura plate-pits lack the central pimple but develop a row of diminutive pegs. No definite function can yet be ascribed to the organ. The dorsal organ described here in Decapoda larvae closely resembles the median sensory tubercle found on the cephalon of some trilobites, especially Trinucleidae. In view of the possible homology between these structures in the two groups, previous interpretation of the trilobite organ as a median eye tubercle must be rejected.

Larval hemolymph feeding: a nondestructive parental cannibalism in the primitive ant Amblyopone silvestrii Wheeler (Hymenoptera: Formicidae)

The queens of larger colonies of the primitive ant Amblyopone silvestrii are exclusively dependent on the hemolymph of their own larvae as a nutrient, even when prey feeding is possible. On the other hand, the foundresses suppress larval hemolymph feeding (LHF) when prey is available, allowing them to rear the first workers more swiftly. The nondestructive form of cannibalism can be regarded as a nutritive adaptation related to: (1) the lack of social food transfer in this species, and (2) its specialized predation on large sporadic prey (centipedes). LHF similar to that in Amblyopone was found in Proceratium and another type of LHF, with a larval specialized exudatory organ, in Leptanilla.

Release of Octopamine From the Photomotor Neurones of the Larval Firefly Lanterns

ABSTRACT The biogenic amine, octopamine, has been proposed as the transmitter in the firefly light organ (Evans, 1980; Robertson, 1981). Whereas initial studies implicated adrenaline (Smalley, 1965; Carlson, 1968a), octopamine was found to be more potent in inducing luminescence than any amine other than synephrine (Carlson, 1968b). Octopamine, but not synephrine, was found in adult lantern segments (Robertson & Carlson, 1976; Copeland & Robertson, 1982) and in larval lantern tissue (Christensen, Sherman, McCaman & Carlson, 1983). Evidence that cyclic nucleotides mediate the effect of octopamine was obtained by Oertel & Case (1976). An octopamine-sensitive adenylate cyclase has been found in the larval lantern and application of exogenous octopamine strongly stimulates cyclic AMP production in adult (Nathanson, 1979) and larval (Nathanson & Hunnicutt, 1979) light organs.