Journal of Experimental Zoology最新文献

{"title":"Anatomy and physiology of neurons composing the commissural ring nerve of the cricket, Acheta domesticus.","authors":"K A Killian,&nbsp;J P Bollins,&nbsp;C K Govind","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The commissural ring nerve (RN) of the cricket Acheta domesticus links together the two cercal motor nerves of the terminal abdominal ganglion. It contains the axons of almost 100 neurons including two bilateral clusters of eight to 13 ventrolateral neurons and approximately 75 neurons with midline somata within the terminal abdominal ganglion. The ventrolateral neurons have an ipsilateral dendritic arborization within the dorsal neuropil of the ganglion and their axons use the RN as a commissure in order to enter the contralateral nerves of the tenth ganglionic neuromere. In contrast, most midline neurons have bifurcating axons projecting bilaterally into the neuropil of the ganglion as well as into the RN where they often branch extensively before entering the contralateral tenth nerves. Most RN neurons have small, non-spiking somata with spike initiation zones distant from the soma. Many midline neurons also produce double-peaked spikes in their somata, indicative of multiple spike initiation zones. Spontaneous neuronal activity recorded extracellularly from the RN reveals several units, some with variable firing patterns, but none responding to sensory stimuli. The RN is primarily composed of small (50 nm diameter) axon profiles with a few large (0.5-1 microm diameter) profiles. Occasionally, profiles of nerve terminals containing primarily small clear vesicles and a few large dense vesicles are observed. These vesicles can sometimes be clustered about an active zone. We conclude that the primary function of the RN is to serve as a peripheral nerve commissure and that its role as a neurohemal organ is negligible. J. Exp. Zool. 286:350-366, 2000.</p>","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 4","pages":"350-66"},"PeriodicalIF":0.0,"publicationDate":"2000-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21537619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Embryonic muscle development in rainbow trout (Oncorhynchus mykiss): a scanning electron microscopy and immunohistological study.","authors":"J Bobe,&nbsp;S Andre,&nbsp;B Fauconneau","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Embryonic muscle development was studied in rainbow trout (Oncorhynchus mykiss) at low and high temperature using scanning electron microscopy (SEM) and immunohistology. Somite development was described starting at stage 16 (Vernier JM. 1969. Ann Embryol Morphogen 4:495-520) for both temperatures, with special interest in their shape and size. Muscle differentiation, associated with somite growth, is characterized by a larger increase in height compared to width and by acquisition of a chevron shape. Thin structures such as striation, sarcomeres, and myofibrils within muscle cells and myotubes were observed starting at the eyed stage (stage 24). Immunohistological analyses showed appearance of embryonic fast myosin at stage 20 in the deep part of the somite. The area where myosin was expressed extended in the somite throughout embryonic development and the presence of myosin was observed in the entire somite at hatching (stage 30). Slow myosin was expressed in a monolayer of superficial cells at the eyed stage and during the entire embryonic development. Then it was expressed in a few layers of cells located in the red muscle area. These results suggest that muscle differentiation, characterized by myosin expression, is engaged at stage 20. Myogenesis starts in the deep part of the somite, near the notochord and progresses laterally to cover the complete somite at hatching when the somite is composed of muscle fibres exhibiting a high degree of maturity. No significant difference was observed in terms of muscular development between low- and high-temperature conditions. J. Exp. Zool. 286:379-389, 2000.</p>","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 4","pages":"379-89"},"PeriodicalIF":0.0,"publicationDate":"2000-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21538103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes along the pituitary-gonadal axis during maturation of the black carp, Mylopharyngodon piceus.","authors":"G Gur,&nbsp;P Melamed,&nbsp;A Gissis,&nbsp;Z Yaron","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The black carp, Mylopharyngodon piceus, is a late-maturing cyprinid reaching sexual maturity at the age of 6-7 years. The present work attempted to define nonfunctional sites along the pituitary-gonadal axis in immature fish utilizing in vivo and in vitro challenge experiments. Two- and 3-year old fish injected with salmon gonadotropin-releasing hormone analog (sGnRHa; 10 microg/kg) and metoclopramide (20 mg/kg) did not reveal any increase in circulating gonadotropin (cGtH) or estradiol (E(2)) level. Furthermore, cGtH release from cultured pituitary cells of fish at these ages did not increase in response to sGnRH (0.1 nM - 1 microM) but was augmented when exposed to TPA (12.5 nM). However, 4-year old female fish did respond to the above treatments both in vivo and in vitro. These results suggest the existence of nonfunctional site(s) proximal to the activation of PKC in the immature black carp gonadotrophs, probably at the level of GnRH receptors. These site(s) start to become functional in 4-year old fish. Two- and 3-year old fish injected with common carp pituitary extract (CPE) containing 350 microg cGtH/kg did not show any increase in circulating E(2). In addition, the estrogen secretion from fragments of the rudimentary gonads did not increase after exposure to CPE containing cGtH (0.5-4 microg/ml) but was elevated dose-dependently by exposure to dbcAMP (0.3-3 mM). However, the ovaries of 4-year old fish did respond to the gonadotropic stimulation, both in vivo and in vitro. These results suggest the existence of other non-functional site(s) in the immature black carp, proximal to the formation of cAMP in the gonads, probably at the level of GtH receptors. These site(s) start to become functional in 4-year old females. Another source of E(2) was discovered in the immature black carp: namely, the fat pad adjacent to the gonads. In contrast to the visceral adipose tissue, the fat pad secretes estrogen in response to cAMP elevation in 2- and 3-year old fish while in 4-year old fish it also responds to gonadotropic stimulation. Due to its large mass and high steroidogenic potency, it is assumed that the gonadal fat pad is involved in the process of puberty in the black carp. J. Exp. Zool. 286:405-413, 2000.</p>","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 4","pages":"405-13"},"PeriodicalIF":0.0,"publicationDate":"2000-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21538105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Alteration of the sex determining system resulting from structural change of the sex chromosomes in the frog Rana rugosa.","authors":"H Ohtani,&nbsp;I Miura,&nbsp;H Hanada,&nbsp;Y Ichikawa","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Rana rugosa in Japan is divided into four geographical races on the basis of the karyotype of the sex chromosomes: one in which heteromorphic sex chromosomes occur in the female sex (ZW/ZZ-system), another in which they are present in males (XX/XY-system), and the remaining two in which no heteromorphism is seen in either sex. The last two inherit the XX/XY sex determining system. Y and Z chromosomes in the former two are of the same karyotype as the no. 7 chromosomes seen in one of the latter two, whereas X and W are caused by two inversions that occurred in the original Xs (no. 7). In this study, we first attempted to detect the structural difference between the resulting X and W by examining their chiasma formation. The chiasma distribution between X and W was closely similar to that between two Xs, suggesting that the W and X are identical in structure. Regarding the change from XX/XY- to ZW/ZZ-system, the simplest explanation is that the putative female-determining gene(s) on the W grew functionally stronger by inversions. Next, we examined the sex of triploids having two Xs and one Z. The data showed that the triploids with two original Xs and a Z were all male, whereas most of those with two resulting Xs and a Z developed into females as expected. We speculated that the female-determining gene(s) on the resulting X grew mildly stronger functionally by position effect, whereas those on the W grew much stronger for some other reason (e.g., duplication). J. Exp. Zool. 286:313-319, 2000.</p>","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 3","pages":"313-9"},"PeriodicalIF":0.0,"publicationDate":"2000-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21509054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aposymbiotic culture of the sepiolid squid Euprymna scolopes: role of the symbiotic bacterium Vibrio fischeri in host animal growth, development, and light organ morphogenesis.","authors":"M F Claes,&nbsp;P V Dunlap","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The sepiolid squid Euprymna scolopes forms a bioluminescent mutualism with the luminous bacterium Vibrio fischeri, harboring V. fischeri cells in a complex ventral light organ and using the bacterial light in predator avoidance. To characterize the contribution of V. fischeri to the growth and development of E. scolopes and to define the long-term effects of bacterial colonization on light organ morphogenesis, we developed a mariculture system for the culture of E. scolopes from hatching to adulthood, employing artificial seawater, lighting that mimicked that of the natural environment, and provision of prey sized to match the developmental stage of E. scolopes. Animals colonized by V. fischeri and animals cultured in the absence of V. fischeri (aposymbiotic) grew and survived equally well, developed similarly, and reached sexual maturity at a similar age. Development of the light organ accessory tissues (lens, reflectors, and ink sac) was similar in colonized and aposymbiotic animals with no obvious morphometric or histological differences. Colonization by V. fischeri influenced regression of the ciliated epithelial appendages (CEAs), the long-term growth of the light organ epithelial tubules, and the appearance of the cells composing the ciliated ducts, which exhibit characteristics of secretory tissue. In certain cases, aposymbiotic animals retained the CEAs in a partially regressed state and remained competent to initiate symbiosis with V. fischeri into adulthood. In other cases, the CEAs regressed fully in aposymbiotic animals, and these animals were not colonizable. The results demonstrate that V. fischeri is not required for normal growth and development of the animal or for development of the accessory light organ tissues and that morphogenesis of only those tissues coming in contact with the bacteria (CEAs, ciliated ducts, and light organ epithelium) is altered by bacterial colonization of the light organ. Therefore, V. fischeri apparently makes no major metabolic contribution to E. scolopes beyond light production, and post-embryonic development of the light organ is essentially symbiont independent. J. Exp. Zool. 286:280-296, 2000.</p>","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 3","pages":"280-96"},"PeriodicalIF":0.0,"publicationDate":"2000-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21509051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Choline dehydrogenase kinetics contribute to glycine betaine regulation differences in chesapeake bay and atlantic oysters.","authors":"L A Perrino,&nbsp;S K Pierce","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Choline dehydrogenase (CD), the first enzyme of the glycine betaine synthetic pathway, was measured in a mitochondrial lysate from gill tissue from Atlantic and Chesapeake Bay oysters acclimated to both 350 and 750 mosm. CD from both populations functions at its maximum rate at 30 degrees C and pH 8.75. Although CD from both populations has a similar affinity for its substrate, choline (K(m) = 15.7 mM), CD V(max) from Atlantic oysters is twice that from Bay oysters. In addition, the CD K(m )doubles and the V(max) increases four-fold in both oyster populations acclimated to 750 mosm. CD activity is competitively inhibited by both betaine aldehyde and glycine betaine. The differences in CD kinetics between the two oyster populations help to account for the lower glycine betaine synthesis rates and concentrations in Chesapeake Bay oysters. CD cannot function rapidly enough to saturate the enzyme, betaine aldehyde dehydrogenase (BADH), immediately downstream, and, therefore, CD kinetics limit the rate of glycine betaine synthesis in oysters. J. Exp. Zool. 286:250-261, 2000.</p>","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 3","pages":"250-61"},"PeriodicalIF":0.0,"publicationDate":"2000-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21509119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Expression of lbx1 involved in the hypaxial musculature formation of the mouse embryo.","authors":"K Uchiyama,&nbsp;A Ishikawa,&nbsp;K Hanaoka","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Somites are the source of hypaxial musculature including skeletal muscles of the limb, tongue, and trunk. To get insight into the function of mouse Lbx1 homeobox gene in early somitic mesoderm differentiation, in situ hybridization analyses were performed. At the 4-6 somite stage (8 dpc), Lbx1 was first expressed in the lateral portion of the epithelial somite and dermomyotomal epithelium. This was in contrast to the expression of myf-5 in the medial region of the somite. The lateral expression of Lbx1 in somitic mesoderm then occurred regionally along the anterior-posterior body axis. Later, at 10 dpc (stage 1 of limb bud development), Lbx1-positive migrating cells originated in the lateral dermomyotomal lips at occipital, forelimb, and hindlimb levels. They also expressed Pax-3 and c-met, known as markers of the migrating limb muscle precursor cells. In stage 4 hindlimb bud (11.5 dpc), the dorsal and ventral muscle precursor populations expressed Lbx1. In stage 8 forelimb buds (12.5 dpc), Lbx1 expression was reduced in the proximal muscle masses, where the high expression of myogenin accompanying muscle differentiation was detected. These results suggest that mouse Lbx1 might be involved in the commitment or determination of a muscle cell subpopulation during hypaxial musculature development. J. Exp. Zool. 286:270-279, 2000.</p>","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 3","pages":"270-9"},"PeriodicalIF":0.0,"publicationDate":"2000-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21509121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rhythmic sensitization of nematocyst discharge in response to vibrational stimuli.","authors":"G M Watson,&nbsp;S Venable,&nbsp;P Mire","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Sea anemones capture prey by discharging nematocysts and other cnidae. Discharge of microbasic p-mastigophore (mpm) nematocysts is regulated in part by hair bundle mechanoreceptors on tentacles arising from multicellular complexes consisting of supporting cells and a sensory neuron. Anemone hair bundles detect movements of prey and then sensitize cnidocytes (cnida-containing cells) to discharge mpm nematocysts in response to contact between the prey and tentacle. Data from a simple bioassay based on counting nematocysts discharged into test probes, indicate that approximately twice as many nematocysts discharge into test probes touched to tentacles after sensitization than before sensitization. We here report that sub-second bursts of vibrational stimuli at key frequencies (51, 55, 65, or 74 Hz; Watson GM, Mire P, Hudson RR. 1998. J Exp Zool 281:582-593) sensitize discharge for at least 90 sec. Very few complete cycles of vibration are sufficient to sensitize discharge. However, as the number of cycles of vibration is increased, discharge is sensitized in rhythmic patterns. Computer analysis of the data by fast Fourier transforms indicates discharge to vibrations at 65 Hz is sensitized every 6.75 cycles. At 51 Hz discharge is sensitized every 2.00 cycles. At 74 Hz, discharge is sensitized in a polyrhythm occurring every 4.26, 3.76, 2.46, and 2. 10 cycles, respectively. At 55 Hz, discharge is sensitized in a polyrhythm occurring every 6.09, 3.20, 2.91, and 2.0 cycles, respectively. Apparently, cells in the neuronal pathway interconnecting anemone hair bundles with cnidocytes count cycles of vibration and then sensitize discharge or not according to the tally. J. Exp. Zool. 286:262-269, 2000.</p>","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 3","pages":"262-9"},"PeriodicalIF":0.0,"publicationDate":"2000-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21509120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enzyme activities involved in lipid metabolism during embryonic development of Macrobrachium borellii.","authors":"M R González-Baró,&nbsp;H Heras,&nbsp;R J Pollero","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The activities of the enzymatic systems involved in the activation and degradation of fatty acids, and in the synthesis of triacylglycerols and phospholipids were studied in vitro using total cellular homogenate and subcellular fractions of eggs of the shrimp Macrobrachium borellii at different developing stages. Egg development was divided into seven stages based on morphological features of the embryo. Palmitoyl-CoA ligase activity increased as the embryo developed and showed its maximum at stage V. An increase in the synthesis of triacylglycerols and diacylglycerols was also observed at this stage. Diacylglycerylethers were synthesized more actively during the first stages of development. The higher specific activity observed in total homogenate than in microsomal fraction suggested that their synthesis was not exclusively microsomal. Phospholipid synthesis was very active all along development, reflecting active membrane biosynthesis. The highest activity of the cytosolic triacylglycerol lipase was observed at stage V. Fatty acid degradation, measured as mitochondrial beta-oxidation activity, did not vary significantly during development. We conclude that both the anabolic and catabolic processes concerning lipid metabolism are very active, with values similar to those described for adult hepatopancreas, revealing the major role of lipids during shrimp embryogenesis energetics, and that the highest activities of lipid synthesis-hydrolysis take place at stage V when embryos are under active organogenesis. J. Exp. Zool. 286:231-237, 2000.</p>","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 3","pages":"231-7"},"PeriodicalIF":0.0,"publicationDate":"2000-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21509117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Betaine aldehyde dehydrogenase kinetics partially account for oyster population differences in glycine betaine synthesis.","authors":"L A Perrino,&nbsp;S K Pierce","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Betaine aldehyde dehydrogenase (BADH), the terminal enzyme of the glycine betaine synthetic pathway was purified 245-fold from the mitochondria of Atlantic and Chesapeake Bay oyster populations acclimated to 350 mosm, using ammonium sulfate precipitation, anion exchange, and affinity chromatography. BADH from both populations functions at its maximum rate at 50-55 degrees C over a broad pH range (7.5-9). BADH activity is also modulated by increased [Na(+)] and [K(+)]. Although BADH from both populations has a similar V(max), BADH from Bay oysters has a substantially lower affinity for its substrate, betaine aldehyde, (K(m) = 0.36 mM), than BADH from Atlantic oysters (K(m) = 0.1 mM). Despite kinetic differences, BADH from both Atlantic and Chesapeake Bay oysters have the same molecular weight based on electrophoretic analysis. These differences in BADH enzyme kinetics between the two oyster populations probably partially explain the lower glycine betaine synthesis rates and concentrations in Chesapeake Bay oysters. J. Exp. Zool. 286:238-249, 2000.</p>","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 3","pages":"238-49"},"PeriodicalIF":0.0,"publicationDate":"2000-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21509118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}