Fish cleaning behaviour of shrimp

Cleaning behaviour of five species of shrimp from three families was studied at three different geographic locations in an effort to gain a quantitative understanding of cleaning behaviour, and to compare a broad cross-section of cleaner shrimp species. Two shrimp from the genus Periclimenes , two from the genus Lysmata , and one from the genus Stenopus were used and 27 hours of recorded laboratory observations were made for each of the five shrimp species.
All shrimp species were inactive most of the observed time, and most spent less than 2% of the observed time cleaning fish hosts. Also, the shrimp spent more time cleaning the ventral rather than the dorsal surface of the fish because they were reluctant to board the fish. However, evenness in cleaning does not appear to be an indicator of overall excellence in cleaning because the two best cleaners (based on number and duration of cleaning bouts) were among the least even in their cleaning.
The fish cleaning behaviour of the shrimp appeared to be strictly stereotypic in form, but the stimulus-response and the total amount of cleaning differed greatly among the five species. A Cleaning Efficiency Index (CEI) was created in an attempt to incorporate significant aspects of the cleaning behaviour. According to this CEI, Lysmata grabhami was by far the most efficient (best) cleaner, CEI = 55–51, compared to the others; Stenopus hispidus , 33–78; Periclimenes pedersoni , 6–29; Periclimenes yucatunicus , 5–60; and Lysmata californien , 2–12.
The cleaners most widely distributed geographically have the highest CEI scores, while the most localized cleaners have the lowest CEIs. This relationship may allow the CEI score to be useful in determining a cleaner shrimp's potential geographical distribution, and may also serve as an indicator for the degree of phylogenetic relationship to other cleaner shrimps.     

A translocation associated, loss-of-function mutation in the nitrogen metabolite repression regulatory gene of Aspergillus nidulans can revert intracistronically

Summary The areA ^r -18 mutation is a loss-of-function mutation in areA, the positive acting regulatory gene mediating nitrogen metabolite repression in Aspergillus nidulans. It results from a reciprocal translocation which splits the coding region into 5 and 3 moieties. Surprisingly, we have selected rare intracistronic revertants of areA ^r -18. From crosses heterozygous for areA ^r -18 revertant alleles, duplication-deficiency progeny containing two copies of a substantial portion of chromosome IV but lacking part of chromosome III, including the 5 moiety of areA, have been obtained. For all four revertants analysed genetically, growth properties of these duplication-deficiency strains indicate that the reversion events involve the 3 portion of areA and that the 5 portion of areA is unnecessary for the revertant phenotype. This conclusion was directly confirmed for one revertant using Southern blotting. As all four reversion events involve additional chromosomal rearrangements, they probably fuse functional promoters, ribosome binding sites and in frame initiation codons to the 3 portion of the gene. In the course of characterisation of these mutations, new mapping data for a large region of chromosome IV have been generated, and a new reciprocal translocation activating the cryptic regulatory gene areB, whose product can substitute for that of areA, has been identified.     

Interactions between developmental processes,growth, and food selection in the larvae and juveniles of Rutilus rutilus (L.) (Cyprinidae)

Summary The aim of this study was to assess the effects of developmental events, occurring in fish during the first weeks after hatching, on the quantity and quality of the ingested food and on growth. The investigation was carried out with the larvae and juveniles of Rutilus rutilus, the single cyprinid species occurring in an oligotrophic subalpine lake in Tirol, Austria. Comparison between availability of prey in the water and gut contents suggests that the selection of food by the young fish is strongly influenced by developmental processes. For example, the prevalence of indigestible phytoplankton in the gut of young larvae can be taken as a sign of the not yet fully developed sensory and locomotory capacities of the young fish (El-Fiky et al. 1987). Furthermore, quantitative and qualitative changes in the gut contents correlate strongly with changes in the form and relative length of the gut, but reflect only weakly the availability of prey in the water. In the Seefelder See population of R. rutilus the switch from a phytoplankton to a cladoceran dominated diet is accompanied by an increase in relative growth rate by nearly one order of magnitude (Wieser et al. 1988).     

Sequence similarities between chicken intestinal 110-kDa ATPase and myosin I-like enzymes

We report the partial amino acid sequence of chicken intestinal microvillar 110-kDa protein that, as a complex with calmodulin, has previously been shown to exhibit myosin-like ATPase and actin-binding activities. The sequence shows a high degree of similarity to the sequence of a novel vertebrate myosin I-like heavy chain encoded by a cDNA isolated from bovine intestine. This confirms that the bovine and chicken proteins are the first examples of Acanthamoeba myosin I-like proteins from higher eukaryotes. Comparison of available structural and functional data leads us to postulate that the myosin I family of proteins result from the fusion of a conserved myosin headlike motor domain, with variable COOH-terminal domains responsible for binding to specific intracellular structures.     

The ras oncogene and tumour metastasis: observations on murine cells transfected with activated human c-Ha-ras

Transfection of cells with cloned genes or total genomic DNA offers a means for studying aspects of neoplastic behaviour. We have used this method to examine whether incorporation of the cloned 6.6-kilobase (kb) fragment of DNA containing the mutant c-Ha-ras human oncogene can confer metastatic capability on murine NIH 3T3 cells. Cells co-transfected with the mutated ras gene and the neomycin resistance marker pSV2neo were selected by culture in neomycin. On subcutaneous inoculation into MF 1 nude mice, these cells proved to be tumourigenic with short latent periods (approximately 14 days)--nude mice were used to circumvent immunological rejection of the mouse cells expressing the product of the human oncogene. Transfectants were capable of lung colonisation after intravenous injection, but there was no evidence of spontaneous metastasis at autopsy, or on histological examination of the lungs and other organs, 90 days after inoculation. Incorporation of the transfected oncogene was confirmed by Southern blotting and its expression by dot-blot hybridisation and immunoprecipitation. The results in this experimental system indicate that transfection of a mutated human ras oncogene into non-neoplastic 3T3 cells can confer part of the metastatic phenotype, namely lung colonisation, but is not by itself sufficient to induce spontaneous metastatic behaviour.     

Radiolysis of DNA in aqueous solution in the presence of a scavenger: A kinetic model based on a nonhomogeneous reaction of OH radicals with DNA molecules of spherical or cylindrical shape

Summary Two expressions are given for the survival dose of DNA exposed to high-energy radiation in aqueous solution in the presence of a scavenger. They are derived from a model where a diffusion controlled reaction of OH radicals occurs on the surface of the DNA macromolecules in competition with scavenging in the bulk of the solution. The DNA molecules are approximated either by spheres or by cylinders. The model based on molecules of spherical shape corresponds closely to that developed by van Rijn et al. [20]. Expressions obtained from the cylindrical model are used to account for the dependence on the scavenger concentration of some experimentally measured quantities, namely the survival dose and theG value for single-strand breaks upon Co -irradiation ofX 174 DNA and polyadenylic acid, respectively.In memoriam Prof. Dr. O.E. Polansky     

Structural comparison of the 68 kDa laminin-binding protein and 5'-nucleotidase from chicken muscular sources: evidence against a gross structural similarity of both proteins

The 68 kDa laminin-binding protein purified from chicken skeletal muscle and the ectoenzyme 5'-nucleotidase from chicken gizzard are both able to interact with laminin. They were both shown to possess a nearly identical amino acid composition. The 79 kDa glycosylated form of 5'-nucleotidase can be transformed into an enzymatically active form by treatment with endoglycosidase F (Endo F). Deglycosylated (Endo F-treated) 5'-nucleotidase exhibits an apparent molecular mass of 68 kDa. Using immunological and finger-printing techniques, both proteins were analysed to determine their structural relatedness. The results obtained indicate that both proteins are not identical but may posses a few common peptides of yet unknown sequence and length.     

Cell attachment properties of collagen type VI and arg-gly-asp dependent binding to its α2(VI) and α3(VI) chains

Twelve of sixteen different cell types including fibroblasts and tumor cells were able to attach and spread on substrates of pepsin-solubilized or intact collagen VI, and on its triple helical domain. Attachment and spreading were independent of soluble mediator proteins (fibronectin, laminin) and collagen VI was distinct from collagens I, IV and V in the cells with which it interacted. Many of the same cells bound and spread on substrates prepared from unfolded α2(VI) and α3(VI) chains but not on the α1(VI) chain. The interactions with the chains were inhibited by low concentrations (10–100 μM) of synthetic RGDS and RGDT but not RGES peptides while the binding of cells to pepsin-solubilized collagen VI was more than 20-fold less sensitive to these peptides. The data incidate that cells have the ability to bind to collagen VI in a specific manner suggesting a similar function for collagen VI in situ.     

Endothelin action on vascular smooth muscle involves inositol trisphosphate and calcium mobilization

Cultured endothelial cells release a potent vasoconstrictor peptide, endothelin. Cumulative addition of synthetic endothelin to isolated rabbit aortic rings elicited a concentration-dependent increase in contractile tension which was endothelium-independent. In cultured rabbit vascular smooth muscle cells loaded with the fluorescent dye fura 2, endothelin induced a concentration-dependent increase in [Ca2+]i over the range of 0.01 to 100 nM. Moreover, in the absence of extracellular Ca2+, endothelin could still induce an increase in [Ca2+]i. In addition, endothelin stimulated 45Ca2+ efflux from preloaded vascular smooth muscle cells in the presence and absence of extracellular Ca2+, as well as stimulating 45Ca2+ influx in a concentration-dependent manner. Measurement of inositol phosphates in [3H]-myoinositol-labelled vascular vascular trisphosphate. Unlabelled endothelin inhibited (125I)-endothelin binding to cultured rabbit vascular smooth muscle cells in a concentration-dependent manner. Binding was not inhibited by other vasoactive hormones or calcium channel ligands, suggesting cell surface receptors specific for endothelin. We conclude that one of the initial membrane events in the action of endothelin is to induce phospholipase C-stimulated PIP2 hydrolysis and that this signalling mechanism is initiated by endothelin/receptor interaction at the plasma membrane.