The Company of Biologists LimitedActa Medica Okayama0022-094920312000Luminal acidification of diverse organelles by V-ATPase in animal cells107116ENMasamitsuFutaiToshihikoOkaGe-hongSun-WadaYoshinoriMoriyamaHiroshiKanazawaYohWadaEukaryotic cells contain organelles bounded by a single membrane in the cytoplasm. These organelles have differentiated to carry out various functions in the pathways of endocytosis and exocytosis. Their lumina are acidic, with pH ranging from 4.5 to 6.5. This article describes recent studies on these animal cell organelles
focusing on (1) the primary proton pump (vacuolar-type H+-ATPase) and (2) the functions of the organelle luminal acidity. We also discuss similarities and differences between vacuolar-type H+-ATPase and F-type ATPase. Our own studies and interests are emphasized.No potential conflict of interest relevant to this article was reported.The Company of Biologists LimitedActa Medica Okayama0022-094920462001Reproductive behaviour in the male cricket Gryllus bimaculatus DeGEER: II. Neural control of the genitalia11391152ENMikihikoKumashiroMasakiSakaiTo understand the neural mechanisms of reproductive behaviour in the male cricket, we identified motor neurones innervating the muscles in each genital organ by backfilling
with cobalt/nickel and recording their extracellular spike activity from nerve bundles of the terminal abdominal ganglion during tethered copulation and spermatophore formation. During tethered copulation, at least two
motor neurones innervating two ipsilateral muscles were activated during projection of the guiding rod of the phallic dorsal pouch. Only one motor neurone, innervating four ipsilateral muscles of the dorsal pouch, was responsible for
spermatophore extrusion by deforming the dorsal pouch. For spermatophore transfer, three motor neurones, singly innervating three epiphallus muscles, played a major role in opening passages for haemolymph to enter the ventral lobes and median pouch by bending the epiphallus. Two
ventral lobe and 3–5 median pouch motor neurones seemed to play a role in expanding or folding the two membranous structures by relaxing or contracting their muscle fibres. After spermatophore transfer, most of the genital motor
neurones exhibited a rhythmic burst of action potentials causing movement of the phallic complex coupled with strong abdominal contractions. For spermatophore formation, the genital motor neurones began to accelerate
their rhythmic bursts approximately 30 s prior to
subgenital plate opening and then changed their activity to tonic bursting or silence. The results have allowed us to describe the timing of the onset and termination of genital muscle contraction more precisely than before, to examine the neural mechanisms of copulatory motor control and to speculate on the neural organization of the reproductive centre for spermatophore extrusion and protrusion.No potential conflict of interest relevant to this article was reported.The Company of Biologists LimitedActa Medica Okayama0022-094920312001Synaptic-like microvesicles, synaptic vesicle counterparts in endocrine cells, are involved in a novel regulatory mechanism for the synthesis and secretion of hormones117125ENYoshinoriMoriyamaMitsukoHayashiHiroshiYamadaShoukiYatsushiroShougoIshioAkitsuguYamamotoMicrovesicles in endocrine cells are the morphological and functional equivalent of neuronal synaptic vesicles. Microvesicles accumulate various neurotransmitters through a transmitter-specific vesicular transporter energized by vacuolar H+-ATPase. We found that mammalian pinealocytes, endocrine cells that synthesize and secrete melatonin, accumulate L-glutamate in their microvesicles and secrete it through exocytosis. Pinealocytes use L-glutamate as either a paracrine- or autocrine-like chemical transmitter in a receptor-mediated manner, resulting in inhibition of melatonin synthesis. In this article, we briefly describe the overall features of the microvesicle-mediated signal-transduction mechanism in the pineal gland and discuss the important role of acidic organelles in a novel regulatory mechanism for hormonal synthesis and secretion.No potential conflict of interest relevant to this article was reported.The Company of Biologists LimitedActa Medica Okayama0022-0949205222002Hatching controlled by the circatidal clock, and the role of the medulla terminalis in the optic peduncle of the eyestalk, in an estuarine crab Sesarma haematocheir34873504ENMasayukiSaigusaEmbryos attached to the female crab Sesarma
haematocheir hatch synchronously within 1 h. Hatching is also synchronized near the time of the expected nocturnal high tide. These events are governed by a single circatidal clock (or pacemaker) in the female crab. The present
study examined the role of the optic peduncle of the eyestalk on hatching and hatching synchrony. Surgery was performed either from the tip of the eyestalk [to remove the region of the optic peduncle from the compound eye–retina complex to the medulla interna (MI)] or from a small triangle 'window' opened on the eyestalk exoskeleton [to create lesions on the medulla
terminalis (MT) of the optic peduncle]. Neither hatching nor hatching synchrony was affected by removal of the region of the optic peduncle from the compound eye–retina complex to the MI: the circatidal rhythm also remained. Removal of the MI probably caused damage to the sinus gland and the bundle of axons running from the sinus gland to the X organ. Nevertheless, maintenance of
highly synchronized hatching indicates that the X
organ–sinus gland system is not related to hatching. Hatching and hatching synchrony were not affected by dorsal-half cuts of the MT: the timing of hatching was not affected either. By contrast, transverse and ventral-half cuts of the MT caused severe damage to most females;
hatching of many females was suppressed, while hatching of some females was either periodic, at intervals of approximately 24 h, or arrhythmic for a few days. The bundle of neuronal axons is tangled in the MT, and the axons inducing hatching pass through the ventral half of
the MT. Complete incision of these axon bundles may have suppressed hatching. Incomplete incision of the axon bundle or partial damage to the neurons may have caused periodic or arrhythmic patterns of hatching. There are
two possible roles for MT in hatching. One possibility is that neurons in the MT only induce hatching under the control of the circatidal pacemaker located in a site
somewhere other than the optic peduncle. Another
possibility is that the circatidal pacemaker is actually present in the MT. The second possibility seems more plausible. Each embryo has a special 48–49.5 h developmental program for hatching. This program could be initiated by the circatidal pacemaker in the female, and
hatching synchrony may also be enhanced by the same pacemaker.No potential conflict of interest relevant to this article was reported.The Company of Biologists LimitedActa Medica Okayama0022-0949200201997Three neural groups in the femoral chordotonal organ of the cricket Gryllus bimaculatus: Central projections and soma arrangement and displacement during joint flexion25832595ENHiroshiNishinoMasakiSakaiThe arrangement of neuronal somata and their
displacement during joint flexion together with the central projection of the pro- and metathoracic femoral chordotonal organs (FCOs) in the cricket were investigated. The FCO consists of the partially fused ventral and dorsal scoloparia in the proximal femur. The
ventrally located neurones (the ventral group) form chainlike rows in which somata became sequentially smallerdistally and project their axons ipsilaterally to the dorsolateral
regions, giving off abundant branches and
terminating in the region between the dorsal intermediatetract and the ventral intermediate tract in the thoracichemiganglion. The dorsal scoloparium, composed of small,simply aggregated neurones, projects exclusively to the medioventral association centre (mVAC), which is known to be an auditory neuropile. In addition, another neural cluster (the dorsal group) was found in the proximo-dorsal region of the ventral scoloparium. This was composed of
simply aggregated neurones with axons giving off sparse branches dorso-laterally and terminating in the peripheral region inside the mVAC. The somata of these three groups were displaced distally by flexion of the femoro-tibial joint:
the ventral group showed the greatest displacement, with the degree of movement depending upon soma location, while the dorsal group and dorsal scoloparium neurones were hardly displaced, possibly because of their strong connection with the cuticle. These properties were similar in both the prothoracic FCO and the metathoracic FCO. Taken together, the above points suggest that there is
greater functional differentiation of the FCO than was previously thought.No potential conflict of interest relevant to this article was reported.The Company of Biologists LimitedActa Medica Okayama0022-094920462001Reproductive behaviour in the male cricket Gryllus bimaculatus DeGEER: I. Structure and function of the genitalia11231137ENMikihikoKumashiroMasakiSakaiWe have investigated the morphology and physiology of the genitalia of the male cricket to establish a basis for neuroethological study of its reproductive behaviour. First, the structure of the phallic complex, including the
dorsal pouch, guiding rod, epiphallus, ventral lobes and median pouch, are described, as are the muscles, cuticle, membranes and biomechanics of copulation. The innervation and sensory receptors have also been examined. Second, the functional role of the muscle in each genital organ has been determined by direct observation
of muscle contraction during spontaneous or evoked movements and by analysis of the changes in movements after the ablation of the muscle. Third, for the flexible membranous organs, the ventral lobes and median pouch, the passages for haemolymph and their dynamic properties have been examined using petroleum jelly. Fourth, the
sequence of coordinated motor actions performed by the internal and external genital organs, which were induced in both restrained and dissected males using newly developed techniques, has been analyzed during tethered
copulation and spermatophore formation. As a result, the mechanisms of copulation and spermatophore formation are now more fully understood.No potential conflict of interest relevant to this article was reported.