摘要:

AbstractThe controlling factors of lachrymal gland secretions were examined in the euryhaline turtle,Malaclemys terrapin. Histochemical and immunocytochemical methods were used to localize some of the possible neurotransmitters involved.There was no immunoreactivity to choline acetyltransferase, the enzyme synthesizing acetyl‐choline, nor did the histochemical technique for acetylcholinesterase produce positive results. Immunofluorescence and immunoperoxidase labels revealed vasoactive intestinal peptide (VIP)‐ and neuropeptide Y (NPY)‐like immunoreactivity in high concentrations surrounding the secretory tubules and ducts. Substance P produced a weak immunoreactivity in the interstitial space surrounding the ducts. Dopamine β‐hydroxylase, the enzyme synthesizing norepinephrine and epinephrine, was localized around the blood vessels. Immunogold labeling confirmed the presence of VIP‐ and NPY‐like reactivity in nerve varicosities close to the basement membrane of the secretory epithelium, and double‐labeling showed VIP and NPY are co‐localized within the same nerve terminals.The results suggest that the secretory epithelium may be primarily under peptidergic control while the vascular system is under adrenergic control. This is possibly a new pattern of innervation for exocrine glands and may be related to the particular function of this salt gland in an euryhaline turtle. © 199

ISSN:0022-104X    

DOI:10.1002/jez.1402730502

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe complex tibial organs of the Ensiferan speciesTroglophilus neglectus(Raphidophoridae, Gryllacridoidea) do not differ significantly in their morphology in all six legs. They consist of a normal developed subgenual organ and an intermediate organ (when compared with the conditions in tettigoniids). Physiologically, the receptor cells of the complex tibial organs of the fore‐ and midlegs could be grouped into 11 functional types. Four of these types belong probably to the intermediate organ; the cells of these types respond to frequencies from 700 Hz to 2,000 Hz to both substrate‐ and airborne sound but are more sensitive to the former. The remaining seven types belong to the subgenual organ. Their receptors are tuned to stimuli within frequencies ranging from 200 Hz to 700 Hz. The classification into different functional types and their attribution to the two receptor organs were derived from a comparison with the physiological properties of the receptors of the complex tibial organs in the midlegs of tettigoniids. In the Troglophilinae the subgenual and intermediate organs are structurally very similar to those of the midleg receptor organs of tettigoniids; only the most distal part of the intermediate organ and the crista acoustica is missing. Consistent with the similarities in the proximal part of the receptor complex, the receptor cells of the subgenual and intermediate organs show similar physiological characteristics. © 1995 Wiley‐Lis

ISSN:0022-104X    

DOI:10.1002/jez.1402730503

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractAs in all decapod Crustacea, the exoskeleton of the land crabGecarcinus lateralisconsists of four layers. Prior electrophoretic analysis of proteins extracted from these layers revealed an abundance of small Mrproteins with acidic pIs as are found in insect cuticle (O'Brien et al. [1991] Biol. Bull.,181:427–441). Further, immunological cross‐reactivity between crab exoskeletal proteins and insect cuticular proteins has been demonstrated (Kumari and Skinner [1993] J. Exp. Zool.,265:195–210). Partial amino acid sequences of a number of proteins from the four exoskeletal layers are described here. Proteins were electrophoresed on two‐dimensional (2D) gels, transferred to polyvinylidene difluoride (PVDF) membranes, and stained; individual spots were recovered and their N‐termini were sequenced. In addition, a 14‐kDa protein (pI =5.4) from membranous layer (ML14) was eluted from 2D gels and digested with endoproteinase Lys‐C; N‐termini of its constituent peptides were sequenced.The two epicuticular proteins differed from each other. Three proteins with identical electrophoretic mobility isolated from exocuticle, endocuticle, and membranous layer appeared to have identical N termini, while another electrophoretically identical set from the three layers appeared identical with each other but differed in three positions from the first set. Two proteins from the membranous layer both had a mass of 25 kDa but different isoelectric points. Their sequences were indistinguishable from each other but clearly distinct from another membranous layer protein. Another distinct sequence was found in a 14‐kDa protein from endocuticle, while a less acidic pair of 14‐kDa proteins from endocuticle and membranous layer were quite similar to one another. The three internal peptide fragments from ML14 were distinct, but one had regions similar to the ML14 N terminus. One crab exoskeletal protein sequence was similar to some structural proteins of vertebrates, whereas others had motifs found in insect cuticular proteins. The sequence similarities identified did not account for the antibody cross‐reactivity.

ISSN:0022-104X    

DOI:10.1002/jez.1402730504

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0022-104X    

DOI:10.1002/jez.1402730505

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractEcdysteroid hormones in crustaceans are synthesized from cholesterol in the Y‐organs. Circulating cholesterol is bound to high‐density lipoprotein (HDL). Experiments were conducted to find the mode of cholesterol uptake by Y‐organ cells. The working hypothesis is as follows: Cholesterol is taken up by endocytosis of the entire HDL‐cholesterol complex. HDL was doubly labeled in the apolipoprotein and cholesterol components with125I and3H, respectively. The time courses of uptake of the two labels by Y‐organ segments in vitro were parallel throughout 24 hr of incubation. Chloroquine, an inhibitor of lysosomal function, had no effect on the uptake and degradation of HDL. Cycloheximide, an inhibitor of protein synthesis, depressed HDL uptake. Transmission electron microscopy of Y‐organ tissue showed features characteristic of adsorptive endocytosis, including coated pits in the plasma membranes and their invagination and vesiculation. Visualization of HDL with immunogold binding showed profiles consistent with endocytosis. Quantitation of the distribution of HDL‐gold particles indicated that about 75% were associated with cellular formed elements, but not with lysosomes, and significantly more particles overall were present in cells from de‐eyestalked crabs than those from intact crabs. These data demonstrate that (a) cholesterol‐carrying HDL is taken into Y‐organ cells by adsorptive endocytosis, (b) its uptake is dependent on de novo protein synthesis, (c) its intracellular processing is independent of lysosomal enzymes, and (d) its uptake is depressed by the molt‐inhibiting hormone secreted by the eyestalks.

ISSN:0022-104X    

DOI:10.1002/jez.1402730506

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe antibacterial properties of the blood cells of the solitary ascidian,Ciona intestinalis, were investigated in vitro. The results show that blood cell lysate supernatants have potent antibacterial activity against a wide range of bacteria. Activity was strongest against Gram positive bacteria, where typically there was a 95‐99% reduction in bacterial viability within 1 h. By contrast, Gram negative bacteria were less susceptible to the antibacterial effects, with the viability of these bacteria generally reduced by approximately 20‐40% after 3 h. Activity against both types of bacteria was further found to be heat‐stable (even after heating to 100°C for 10 min or freezing to −20°C for up to 1 month), Ca2+‐but not Mg2+‐dependent, and active at very low titres. Comparison of the antibacterial vigour of lysate supernatants made from separated blood cell populations revealed that activity resides mainly in the morula cells with some, albeit weaker, activity also detectable in the hyaline amoebocytes. No activity was present in the plasma. Preliminary investigations into the mode of action of the active factors indicate that the response is not due to lysozyme, is not directly lytic in character, and is not attributable to agglutination. Instead, as preliminary characterization by gel filtration on Sephadex G‐75 revealed 4 main protein peaks, with antibacterial activity confined to peak 3 (molecular weight range of 8‐15 kDa), the phenomenon seems to be due to the action of one or more low molecular weight proteins. The location, action, and release of these factors appear to differ from those of the cecropins and defensins described in other animal groups. © 19

ISSN:0022-104X    

DOI:10.1002/jez.1402730507

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractA recent report has concluded that heat flow under anoxia from encysted embryos of the brine shrimpArtemiais unmeasurable (Hontoria et al. [1993] J. Exp. Biol.,178:149–159). This observation contrasts with two earlier communications that have reported low but measurable energy flow from these gastrulae (Hand and Gnaiger [1988] Science,239:1425–1427; Hand [1990] J. Comp. Physiol. [B],160:357–363). In order to re‐examine this issue, up to 20 g wet mass of embryos was loaded per experiment into sealed ampoules (25‐ to 50‐fold more tissue than in previous studies) and calorimetric analyses were conducted. Even after 50–60 h, a clearly measurable heat dissipation was recorded from these anoxic embryos (0.0128 ± 0.0007 mW·g dry mass−1; ± 1 SE, n =6). The results confirm the presence of measurable heat flow under anoxia. The rate of heat dissipation measured in this study is at the limit of detection for the instrument used by Hontoria et al. ([1993] J. Exp. Biol.,178:149–159). A second important issue is whether any of the low heat flow under anoxia is associated with processes involving ATP turnover, a point that is evaluated in this study but that remains unresolved. However, calculations suggest that macromolecular degradation may explain a significant portion of the anoxic heat flow. ©

ISSN:0022-104X    

DOI:10.1002/jez.1402730508

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0022-104X    

DOI:10.1002/jez.1402730501

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY