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  • 1
    Electronic Resource
    Electronic Resource
    Infectivity in mouse fibroblasts of polyoma DNA integrated into plasmid pBR322 or lambdoid phage DNA (1979)
    [s.l.] : Nature Publishing Group
    Nature 279 (1979), S. 811-816 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Hybrid plasmid molecules were made with DNA from a readily identifiable mutant of polyoma3 (which lacked an Hha restriction site) by digestion with restriction enzymes EcoRl or BamHI, each of which cleaves at a single site, and ligation to appropriately cleaved pBR322. The molar ratios of viral to ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/279811a0
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  • 2
    Electronic Resource
    Electronic Resource
    Morphology and ultrastructure of the gills of terrestrial crabs (Crustacea, Gecarcinidae and Grapsidae): Adaptations for air-breathing (1992)
    Springer
    Zoomorphology 112 (1992), S. 39-49 
    Details
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The terrestrial crabsGeograpsus grayi, Geograpsus crinipes, Cardisoma hirtipes andGecarcoidea natalis have a reduced number of gills and show a reduced planar gill surface (SA) compared to aquatic species. Gill lamellae are stiffened and thickened (increasing blood/gas (BG) diffusion distances) and nodules maintain wide spacing between lamellae. Haemolymph is directed through the gill lamellae by rows of pillar cells and in the afferent region an intralamellar septum splits the haemolymph into two parallel networks. Gaps in the lines of pillar cells allow movement of haemolymph between adjacent channels. The afferent vessel distributes haemolymph to the lamella via a number of direct channels including the marginal canal and in large gills with the aid of a long, forked sinus which supplies the ventral and central regions of the lamellae. The marginal canal functions in both distribution and collection of haemolymph; the role varies with species. Potential flow-control sites were identified at the junctions between afferent and efferent areas and where the efferent channels enter the efferent branchial vessel. Each gill receives a branch from the sternal artery which supplies all the lamellae. Transport epithelia is the principal cell type in the gills of all species examined though its location varies between species, either being confined to certain gills or specific parts of the lamellae. The gill lamellae of air-breathing crabs are clearly modified to breathe air (stiffening and presence of nodules), though the overall contribution of the gills to gas exchange has been reduced (smaller SA and longer BG diffusion distances). The role of the gills in air-breathing crabs thus appears to have switched from one of an efficient aquatic gas-exchanger (thin with large surface area) and transport tissue, to one that is predominantly set up for ion-regulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01632993
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  • 3
    Electronic Resource
    Electronic Resource
    Enzymes of urate synthesis and catabolism in the Gecarcinid land crab Gecarcoidea natalis (1998)
    Springer
    Experimental biology online 3 (1998), S. 1-11 
    Details
    ISSN: 1430-3418
    Keywords: Gecarcoidea natalis ; Land crab ; Urate metabolism ; Urate ; Urease ; Uricase ; Xanthine dehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study investigated the sites of urate synthesis and catabolism in the gecarcinid land crab Gecarcoidea natalis by assaying spongy connective tissue, midgut gland, muscle and gill for xanthine oxidoreductase, the last enzyme involved in urate synthesis, and uricase and urease, the first and last enzymes involved in urate catabolism. The spongy connective tissue and midgut gland of the G. natalis contained activities of xanthine oxidoreductase and were considered to be sites of urate synthesis. The midgut gland had a high activity of xanthine oxidoreductase [(58.87±4.6 (SE) nmol urate produced g-1 wet wt. tissue min-1], 2.7 times the xanthine oxidoreductase activity contained within the spongy connective tissue, and was thought to be the main site of urate synthesis. Xanthine dehydrogenase (EC 1.1.1.204) was the only form of xanthine oxidoreductase detected within the tissues. Its presence means that the cost of synthesising urate de novo is relatively small (between 1 and 3 ATP). Uricase (EC 1.7.3.3) and urease (EC 3.5.1.5) activities were present in the tissues of G. natalis. Spongy connective tissue contained the highest activities of uricase [48.44±4.29 (SE) nmol urate consumed g-1 wet wt. tissue min-1] while the highest activities of urease [365.31±37.21 (SE) nmol urate consumed g-1 wet wt tissue min-1] were contained within the gills. From this evidence it is clear that G. natalis possesses the uricolytic pathway and hence the ability to catabolise urate, and urate catabolism is begun at the site of urate storage, the spongy connective tissue, and is completed at the gills. As the gills are the site of ammonia excretion in this species the ammonia produced from the catabolism of urate is probably excreted. The urate deposits within the body of G. natalis may be involved in temporary storage of nitrogenous wastes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00898-998-0005-3
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  • 4
    Electronic Resource
    Electronic Resource
    The morphology and vasculature of the lungs and gills of the soldier crab, Mictyris longicarpus (1987)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 193 (1987), S. 285-304 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The five gill pairs of Mictyris longicarpus have the lowest weight specific area reported for any crab. The cuticle of the gill lamellae is lined with epithelial cells which have structural features characteristic of iontransporting cells. Pillar cells are regularly distributed in the epithelium and serve to maintain separation of the two faces of the lamellae. The central hemolymph space is divided into two sheets by a fenestrated septum of connective tissue cells. The dorsal portion of the marginal canal of each lamella receives hemolymph from the afferent branchial vessel and distributes it to the lamella while the ventral portion of the canal collects hemolymph and returns it to the efferent branchial vessel.The lung is formed from the inner lining of the branchiostegite and an outgrowth of this, the epibranchial membrane. Surface area is increased by invagination of the lining which forms branching, blind-ending pores, giving the lung a spongy appearance. The cuticle lining the lung is thin and the underlyng epithelial cells are extremely attenuated, giving a total hemolymph/gas distance of 90-475 nm. Venous hemolymph is directed close to the gas exchange surface by specialised connective tissue cells and by thin strands of connective tissue which run parallel to the cuticle. Air sacs are anchored in position by paired pillar cells filled with microtubules. Afferent hemolymph is supplied from the eye sinus, dorsal sinus, and ventral sinus. Afferent vessels interdigitate closely with efferent vessels just beneath the respiratory membrane. The two systems are connected by a “perpendicular system” which ramifies between the airways and emerges to form a sinus beneath the carapace and then flows back between the air sacs to the efferent vessels. The afferent side of the perpendicular system is the major site of gas exchange. Efferent vessels return via large pulmonary veins to the pericardial cavity. PaO2 levels were high (95.5 Torr), indicating highly efficient gas exchange.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051930307
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  • 5
    Electronic Resource
    Electronic Resource
    Land crabs with smooth lungs: Grapsidae, Gecarcinidae, and Sundathelphusidae ultrastructure and vasculature (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 245-260 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The highly terrestrial grapsids and gecarcinids and the amphibious sundathelphusids all have large, expanded branchial chambers. The lining of the branchial chambers is smooth and well vascularized, and it functions as a lung. The respiratory membrane and the cuticle lining the lung are extremely thin (200-350 nm). The blood vessels within the lung are formed from connective tissue cells supported by collagen fibres and lined by a basal lamina. The major vessels in the lung are embedded deep in the branchiostegite and lie just beneath the thick outer carapace. These vessels branch towards the respiratory membrane, where they eventually lose their connective tissue coverings to form thin, flattened lacunae directly below the respiratory epithelium. The lacunae (exchange sites) are bordered by specialized connective tissue cells, which either bear microvilli on their apical surface (fimbriated cells) or are very smooth. The respiratory circulation in the lung is very complex, with two portal systems present between the afferent and efferent systems, producing a total of three lacunal exchange beds. Portal systems increase the surface area available for gas exchange. The major distributing vessel in the lung is the branchiostegal vein, which runs along the inner margin of the branchiostegite. The main venous supplies come anteriorly from the infraorbital and ventral sinuses and posteriorly from the procardial sinus. The main collecting vessel is the pulmonary vein, which arises anteriorly and which runs around the ventral perimeter of the branchiostegite before emptying into the pericardial sinus. © 1993 Wiley-Liss, Inc.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052150306
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  • 6
    Electronic Resource
    Electronic Resource
    The venous system of the terrestrial crab Ocypode cordimanus (Desmarest 1825) with particular reference to the vasculature of the lungs (1984)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 181 (1984), S. 133-142 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The respiratory system of Ocypode cordimanus consists of seven pairs of gills, modified for aerial gas exchange, and a single pair of lungs. Each lung is formed from the inner surface of the branchiostegite and the thoracic wall of the branchial chamber. The branchiostegal surface is increased by a fleshy infolding, the branchiostegal shelf, whilst the surface area of the thoracic lung wall is enhanced by a large flaplike fold.The anatomy of the major sinus systems and the vascular supply to the lungs were investigated. Venous hemolymph is supplied to the lungs potentially from all the major body sinuses. The dorsal, ventral, hepatic, and infrabranchial sinuses are all connected anteriorly to the two eye sinuses which distribute hemolymph to the lungs. Each eye sinus gives off five branches to the branchiostegal lung surface and one to the thoracic lung wall. These afferent vessels are highly branched and interdigitate closely with efferent vessels. The two systems are connected by flat lacunae lying just beneath the respiratory epithelium and these are believed to be the site of gas exchange. The efferent vessels empty into two pulmonary veins on each side, one serving the branchiostegal lung wall and the other the thoracic wall. The two vessels on each side fuse before joining the pericardial cavity as a single trunk on each side.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051810202
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  • 7
    Electronic Resource
    Electronic Resource
    Sodium regulation in the freshwater/land crabHolthuisana transversa (1981)
    Springer
    Journal of comparative physiology 142 (1981), S. 451-456 
    Details
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Holthuisana transversa maintains sodium balance at very low external concentrations (7–25 μM). This is achieved by the high affinity of the uptake mechanism (K m=0.18 mM), a low rate of sodium loss (0.17 μmol g−1h−1) and a large increase in the rate of sodium uptake after depletion. The site of sodium absorption is the gills and extraction of sodium from respired water by sodium-depleted crabs can be as high as 28%. Crabs tolerate direct transfer to 80% sea-water and, following acclimation, the sodium and calcium levels of the haemolymph are maintained above those of the medium while the level of magnesium is significantly lower.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688975
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  • 8
    Electronic Resource
    Electronic Resource
    Oxygen and carbon dioxide transport by the haemocyanin of an amphibious crab,Holthuisana transversa (1988)
    Springer
    Journal of comparative physiology 157 (1988), S. 873-882 
    Details
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The oxygen and carbon dioxide transporting properties of the haemolymph from an amphibious Australian crab,Holthuisana transversa were investigated. Within the temperature range 15 to 35°C increasing temperature markedly decreased oxygen affinity (ΔH=−54 kJ·mol−1). The Bohr effect was small at all temperatures with a mean value of −0.13. Over the temperature range 15–35°C there was a significant increase in the cooperativity of oxygen binding. Changing the concentration of Ca,l-lactate or haemocyanin in the haemolymph could elicit no significant change in either O2 affinity or cooperativity of O2 binding. There was no evidence in support of a specific effect of CO2 on oxygen affinity of either non-dialysed or dialysed haemolymph. The amount of CO2 that could be carried byH. transversa haemolymph was significantly reduced by increased temperature (approx. 14 to 12.5 mmol·l−1 CO2). Comparisons of oxygenated and deoxygenated haemolymph at a fixed pH were unable to demonstrate the presence of a significant Haldane effect. Combining data from oxygenated and deoxygenated haemolymph the buffer value was calculated to be in the range −6.2 to −8.5 mmol·l−1 HCO 3 − ·pH unit−1. The insensitivity ofH. transversa haemocyanin function to all modulating influences except temperature is discussed with respect to the ecology of this crab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00691020
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  • 9
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    The expression of biologically active cholera toxin inEscherichia coli (1982)
    Oxford University Press
    Details
    Publication Date: 1982-01-01
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
    Published by Oxford University Press
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  • 10
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    Nucleotide sequences within the cholera toxin operon (1983)
    Oxford University Press
    Details
    Publication Date: 1983-01-01
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
    Published by Oxford University Press
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