Neuroendocrine control of vitellogenesis in the dragonfly, Orthetrum chrysis (Selys) (Odonata: Libellulidae).

1. Histological correlative studies on the cerebral neurosecretory cells, the corpora allata and the oocyte development strongly suggest the involvement of cerebral NSM mostly produced by the A cells of pars intercerebralis and the CA hormone in the vitellogenesis. 2. Biochemical studies reveal the incorporation of haemolymph proteins and lipids in the yolk during vitellogenesis. 3. Exogenous administration of the extract of the brain-CC and FME demonstrates, to some extent, the stimulation of protein synthesis during vitellogenesis in the haemolymph by the cerebral NSM and the CA hormone, while the lipid metabolism lies, mostly, under the control of juvenile hormone.     

Neurosecretory system of the ventral ganglia in the dragonfly,Orthetrum chrysis (selys) (Odonata: Libellulidae)

Summary The neurosecretory cells of the ventral ganglia in the adult dragonfly, Orthetrum chrysis, are classified into A, B, C1 and C2 cells. The neurosecretory material in the ventral ganglia is composed of PAS-positive material with 1-, 2-glycol groups and some proteins. The proteins rich in cystine or cysteine occur predominantly in the A cells, moderately in C cells and negligibly in B cells. Proteins containing arginine occur in A and B cells only, and those containing basic amino acids occur in C2 cells. The neurosecretory pathways and the neurohemal organs are also described.     

The histological and histochemical studies on the ovary in relation to vitellogenesis in the dragonfly, Orthetrum chrysis Selys (Libellulidae: Odonata).

The ovaries consist of large number of panoistic ovarioles in the last instar nymph and the adult dragonfly Orthetrum chrysis (Selys). In the nymph the vitellaria are compactly filled with the primary oocytes and the vitellogenesis takes place only in the adult stage. During vitellogenesis oocytes change widely in their shape, size and cytological organisation and their developmental stages can be divided into pre-vitellogenic, early-vitellogenic, vitellogenic, late-vitellogenic and maturation age. PAS-positive material appears first around the germinal vesicle in the early-vitellogenic stage and lateron it migrates towards the periphery. Glycogen appears in the late-vitellogenic stage. DNA is abundantly present in the nuclei of the oocytes during the pre-vitellogenic and completely absent in early-vitellogenic, vitellogenic, late-vitellogenic and maturation stages. It is observed in the nuclei of follicular epithelial cells of all the stages. RNA is abundantly present in cytoplasm of the pre-vitellogenic oocytes but lateron is gradually decreases. During the early-vitellogenic and vitellogenic stages high concentration of RNA in the follicular epithelial cells has been observed. The protein bodies appear first in the interfollicular spaces and towards the periphery of the oocytes just near the enveloping follicular epithelial cells, during the early-vitellogenic stage suggesting the formation of yolk proteins from the haemolymph. In Orthetrum chrysis the sudanophilic bodies appear first in the follicular cells and then lie in the peripheral region of the oocytes suggesting the incorporation of yolk lipid either from the follicular epithelium or from the haemolymph through the follicular epithelium. The phospholipids are synthesised in pre-vitellogenic to the late-vitellogenic stages. In the late-vitellogenic stages the phospholipid granules are present abundantly in the follicular epithelium while in the maturation stage they disappear suggesting their utilisation in the formation of membranes like vitelline and chorion. The neutral fats are present in the form of large number of droplets in the oocytes during the maturation stage.     

Reproductive behavior of the dragonfly,Orthetrum japonicum (Odonata: Libellulidae)

The reproductive behavior of the dragonfly,Orthetrum japonicum, is described. Behavioral processes of turnover of territorial males, simultaneous guarding of 2 females by a male, and copulation by non-territorial males are described. The males with longer hind wings won the territorial conflicts more frequently. The total duration of territorial residence of a given male was correlated with the number of his matings, but not correlated with the length of his abdomen or hind wings. The territorial site with the lower degree of vegetation cover was occupied by males more consistently. Males in more consistently occupied territorial sites did not have longer abdomen and hind wings than males in less consistently occupied sites. The territorial site where the larger number of copulations was observed was not occupied more consistently. Selection episode analysis using the method of Arnold & Wade (1984a, b) showed that direct selection on the hind wing length favored the short wing and that direct selection on the abdomen length favored the long abdomen during mating.     

Selection and reproductive success in males of the dragonfly,Orthetrum japonicum (Odonata: Libellulidae)

Reproductive success, copulation success, and mating success were measured for a population of male dragonflies,Orthetrum japonicum. Copulation success explained the greatest variation in reproductive success. The proportion of copulations followed by oviposition was positively correlated with the number of oviposited eggs per mating. Directional selection on four morphological characters was estimated. The effect of selection on correlated traits was comparable to that of direct selection. Directional selection varied between traits and between episodes in a single trait. The probability that the observed directional selection on the four morphological traits was expected under the condition of the selective neutrality of traits was not smaller than 5%.     

Mechanisms of sperm removal and sperm transfer in Orthetrum coerulescens (Fabricius) (Odonata: Libellulidae)

ABSTRACT An account of the structure of the secondary genitalia of male Orthetrum coerulescens (Fabricius) is given together with an outline of the internal genitalia of the female. Observations on the experimental inflation of the penis are described. No sperm was released during fast inflations and deflations of the penis, but sustained inflation of the penis led to the release of a clear fluid followed by the slow discharge of sperm. Examination of natural copulations in the field has shown that rapid rhythmic movements at up to 5 Hz take place in the male's third abdominal segment throughout most of copulation, but towards the end they cease though inflation is maintained. It is suggested that the rapid movements coincide with the removal of rival sperm from the female and that sperm is transferred to the female only during the maintained inflation. Possible mechanisms of sperm translocation, sperm removal and sperm transfer are discussed with reference to male and female genital structures and the action of relevant muscles.     

Fecundity and oviposition in three skimmers,Orthetrum japonicum,O. albistylum andO. triangulare (Odonata: Libellulidae)

Females of three skimmers,Orthetrum japonicum, O. albistylum andO. triangulare, were captured in forests and paddy fields. They were dissected and examined for the number of submature and mature eggs.Orthetrum japonicum andO. albistylum continuously developed eggs throughout their reproductive period. The volume of mature eggs inO. albistylum was the smallest among the three species. The number of mature eggs in ovaries decreased from morning to afternoon, suggesting that all of them oviposited around noon. The number of mature eggs laid byO. japonicum, O. albistylum andO. triangulare was estimated at about 400, 800 and >2000 a day, respectively.     

The structure and function of the genitalia in the Libellulidae (Odonata)

An outline of the morphology of the secondary genitalia of libellulid dragonflies is given together with a more detailed treatment of the components of the fourth (distal) segment of the penis. The variations of penis structure in 70 species, representing ten of the 11 subfamilies, are surveyed and catalogued. There is remarkable diversity in the presence and form of penis structures, particularly those associated with the medial process, namely the flagelium, cornua and inner lobes. A comparable survey of females shows that they can be provisionally divided into ten types according to the number and size of their sperm-storage organs. Comparisons of penis structures with the sperm-storage organs of females suggests that in species whose females store large amounts of sperm, usually doing so in one or a pair of organs, males possess highly extensible, lobate and bristly penes, commonly equipped with cornua. By contrast, in those species in which the females store small volumes of sperm, usually doing so in three organs, the penes bear either flagella equipped with proximally directed spines or with large terminal barbs, or they have narrow, spiny inner-lobes which resemble flagella. Some functional interpretations are proposed in the light of sperm competition. The variability of genital structure can be interpreted adaptively and does not closely reflect phylogenetic relationships. Functionally convergent structures have evolved a number of times from different origins.     

Sexual difference of lifetime movement in adults of the Japanese skimmer,Orthetrum japonicum (Odonata: Libellulidae), in a forest-paddy field complex

The mark-and-recapture method was used to study the lifetime movement of the Japanese skimmer,Orthetrum japonicum, in a forest-paddy field complex in the warmtemperate zone of Japan. The flight season was from mid April to late June. The age structure showed that the maiden flight occurred towards the forest from the emergence sites (paddy fields) for both sexes. The insects returned to the paddy fields after maturation. The total number of skimmers estimated in the whole survey area was about 1000–2000, of which about 200 males were found in the paddy fields. The average lengths of the immature and reproductive periods were about 10 and 20 days in both sexes, respectively. Most mature males tended to stay in the paddy fields and showed territorial behavior, while most mature females moved frequently between the forest and the paddy fields. The average extent of each territory was about 19 m², being established mainly in the shady paddy fields. Few males were sneakers. The available habitat throughout the life span for the skimmers was both the paddy fields and the forest.     

Culturing Microglia from the Neonatal and Adult Central Nervous System

Microglia are the resident macrophage-like cells of the central nervous system (CNS) and, as such, have critically important roles in physiological and pathological processes such as CNS maturation in development, multiple sclerosis, and spinal cord injury. Microglia can be activated and recruited to action by neuronal injury or stimulation, such as axonal damage seen in MS or ischemic brain trauma resulting from stroke. These immunocompetent members of the CNS are also thought to have roles in synaptic plasticity under non-pathological conditions. We employ protocols for culturing microglia from the neonatal and adult tissues that are aimed to maximize the viable cell numbers while minimizing confounding variables, such as the presence of other CNS cell types and cell culture debris. We utilize large and easily discernable CNS components (e.g. cortex, spinal cord segments), which makes the entire process feasible and reproducible. The use of adult cells is a suitable alternative to the use of neonatal brain microglia, as many pathologies studied mainly affect the postnatal spinal cord. These culture systems are also useful for directly testing the effect of compounds that may either inhibit or promote microglial activation. Since microglial activation can shape the outcomes of disease in the adult CNS, there is a need for in vitro systems in which neonatal and adult microglia can be cultured and studied.     

Growth Arrest Specific 1 (GAS1) Is Abundantly Expressed in the Adult Mouse Central Nervous System

Growth arrest specific 1 (GAS1) is a pleiotropic protein that induces apoptosis and cell arrest in different tumors, but it is also involved in the development of the nervous system and other tissues and organs. This dual ability is likely caused by its capacity to interact both by inhibiting the intracellular signaling cascade induced by glial cell-line derived neurotrophic factor and by facilitating the activity of the sonic hedgehog pathway. The presence of GAS1 mRNA has been described in adult mouse brain, and here we corroborated this observation. We then proceeded to determine the distribution of the protein in the adult central nervous system (CNS). We detected, by western blot analysis, expression of GAS1 in olfactory bulb, caudate-putamen, cerebral cortex, hippocampus, mesencephalon, medulla oblongata, cerebellum, and cervical spinal cord. To more carefully map the expression of GAS1, we performed double-label immunohistochemistry and noticed expression of GAS1 in neurons in all brain areas examined. We also observed expression of GAS1 in astroglial cells, albeit the pattern of expression was more restricted than that seen in neurons. Briefly, in the present article, we report the widespread distribution and cellular localization of the GAS1 native protein in adult mammalian CNS.     

L(1)trol and L(1)devl, Loci Affecting the Development of the Adult Central Nervous System in Drosophila Melanogaster

Adult optic lobes of Drosophila melanogaster are composed of neurons specific to the adult which develop postembryonically. The structure of the optic lobes and aspects of its development have been described, and a number of mutants that affect its development have been identified. The focus of every screen to date has been on disruption of adult structure or function. Although these loci were originally identified on the basis of viable mutants, some have proven capable of giving rise to lethal alleles. It seems reasonable to assume that mutants which strongly affect development of the imaginal-specific central nervous system may evidence abnormalities during the late larval or pupal stages when the adult central nervous system is undergoing final assembly and might show a lethal phase prior to eclosion (as is true for mutations at the previously defined l(1)ogre locus). We have carried out the first screen of autosomal and sex-linked late larval and pupal lethals to identify mutations that affect the development of the optic lobes. Our screen yielded nine mutants that could tentatively be grouped into three classes, depending on the neuroblast population affected and imaginal disc phenotypes. Two of these, including one that is allelic to l(1)zw1, were chosen for further analysis.     

The Orexin System in the Enteric Nervous System of the Bottlenose Dolphin (Tursiops truncatus)

This study provides a general approach to the presence and possible role of orexins and their receptors in the gut (three gastric chambers and intestine) of confined environment bottlenose dolphin. The expression of prepro-orexin, orexin A and B and orexin 1 and 2 receptors were investigated by single immunostaining and western blot analysis. The co-localization of vasoactive intestinal peptide and orexin 1 receptor in the enteric nervous system was examined by double immunostaining. Also, orexin A concentration were measured in plasma samples to assess the possible diurnal variation of the plasma level of peptide in this species. Our results showed that the orexin system is widely distributed in bottlenose dolphin enteric nervous system of the all gastrointestinal tract examined. They are very peculiar and partially differs from that of terrestrial mammals. Orexin peptides and prepro-orexin were expressed in the main stomach, pyloric stomach and proximal intestine; while orexin receptors were expressed in the all examined tracts, with the exception of main stomach where found no evidence of orexin 2 receptor. Co-localization of vasoactive intestinal peptide and orexin 1 receptor were more evident in the pyloric stomach and proximal intestine. These data could suggest a possible role of orexin system on the contractility of bottlenose dolphin gastrointestinal districts. Finally, in agreement with several reports, bottlenose dolphin orexin A plasma level was higher in the morning during fasting. Our results emphasize some common features between bottlenose dolphin and terrestrial mammals. Certainly, further functional investigations may help to better explain the role of the orexin system in the energy balance of bottlenose dolphin and the complex interaction between feeding and digestive physiology.     

The antennal lobe of Libellula depressa (Odonata,Libellulidae)

Here we describe the antennal lobe of Libellula depressa (Odonata, Libellulidae), identified on the basis of the projections of the afferent sensory neurons stemming from the antennal flagellum sensilla. Immunohistochemical neuropil staining as well as antennal backfills revealed sensory neuron terminal arborizations covering a large portion of the antennal lobe. No clear glomerular structure was identified, thus suggesting an aglomerular antennal lobe condition as previously reported in Palaeoptera. The terminal arbors of backfilled sensory neurons do, however, form spherical knots, probably representing the connections between the few afferent neurons and the antennal lobe interneurons. The reconstruction revealed that the proximal part of the antennal nerve is divided into two branches that innervate two spatially separated areas of the antennal lobe, an anterioventral lobe and a larger posteriodorsal lobe. Our data are consistent with the hypothesis that one tract of the antennal nerve of L. depressa contains olfactory sensory neurons projecting into one of the sublobes, while the other tract contains thermo-hygroreceptive neurons projecting into the other sublobe.     

The larva of Libellula foliata (Kirby, 1889) (Odonata: Libellulidae)

The larva of Libellula foliata (Kirby) is described based upon mature larvae from the Biosphere Reserve of ??El Triunfo?? in the state of Chiapas. It belongs to the small group of species without dorsal protuberances, L. composita (Hagen), L. comanche Calvert and L. saturata Uhler. The following combination of characters permits the separation of L. foliata larva from the other aforementioned larvae: tergites 6?C10 uniformly colored, no lateral spines on segments 8?C9, 5?C6 palpal setae and 3 long premental setae. After this finding, only the larvae of Libellula gaigei Gloyd and L. nodisticta Hagen remain undiscovered for the Mexican species of Libellula.     

Hygroreceptors in the larva of Libellula depressa (Odonata: Libellulidae)

Ultrastructural and electrophysiological (single-cell recordings) investigations were carried out on the coeloconic sensilla borne by the apical antenna of the larvae of Libellula depressa (Odonata: Libellulidae). These sensilla appear as pegs located in pits. One of them is a compound sensillum constituted of two fused pegs in a common pit and the other two are single pegs located in separated pits close to each other. Coeloconic sensilla show position and ultrastructural details very similar to those described in insect hygroreceptors. The electrophysiological recordings on the apical antennae of the last larval instar of L. depressa clearly show the presence of moist and dry cells responding antagonistically to humidity changes. This study gives the first evidence of hygroreceptors in dragonfly larvae and represents the first electrophysiological approach to larval sensilla of aquatic insects. The presence of hygroreceptors in L. depressa larvae is in agreement with the hygropositive response shown by these insects in laboratory and field behavioural experiments.     

G-CSF (Granulocyte-Colony Stimulating Factor) in the Central Nervous System

G-CSF (Granulocyte-colony stimulating factor) is a hematopoietic growth factor that has been known for 20 years, and has been named for its role in the proliferation and differentiation of cells of the myeloic lineage. We have uncovered a novel spectrum of activities of G-CSF in the central nervous system. G-CSF and its receptor are expressed by neurons in many brain regions, and are upregulated upon experimental stroke. In neurons, G-CSF acts anti-apoptotically by activating several protective pathways. In vivo, G-CSF decreases infarct volumes in acute stroke models in rodents. Moreover, G-CSF stimulates neuronal differentiation of adult neural stem cells in the brain, and improves long-term recovery in more chronic stroke models. Thus, G-CSF is a novel neurotrophic factor, and a highly attractive candidate for the treatment of neurodegenerative conditions. Here we discuss this new property of G-CSF in contrast to its known functions in the hematopoietic system, summarize data from other groups on G-CSF’s actions in cerebral ischemia, compare G-CSF to Erythropoietin (EPO) in the CNS and highlight clinical implications.     

The antennal sensilla of the adult of Libellula depressa (Odonata: Libellulidae)

An ultrastructural investigation (SEM, TEM) on the antennal flagellum of the adult of the dragonfly Libellula depressa (Odonata:Libellulidae) revealed sensilla located in pits on the lateral-ventral side of the antenna. These sensilla are represented by sensilla coeloconica and by deeply sunken sensilla. The sensilla coeloconica are innervated by three unbranched dendrites, which enter the peg and show a dendrite sheath ending at the base of the peg. The peg has no socket and its cuticle is irregular with wide pore-like structures at the base of which actual pores are visible. The structure of these coeloconic sensilla is in agreement with that reported for single-walled insect chemoreceptors. The deeply sunken sensilla are represented by two kinds of sensilla styloconica, named type-1 and type-2, located at the bottom of deep cavities appearing as simple openings on the antennal surface. These sensilla are no-pore sensilla with inflexible socket and unbranched dendrites and, notwithstanding their structural differences, share common features typical of thermo/hygroreceptors. The presence of chemoreceptors in adult dragonflies sheds light on evolutionary trends in insect perception; the previously unknown occurrence of thermo/hygroreceptors in dragonflies is very important in view of the reported ability of Odonata to thermoregulate heliothermically.