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Behavioural adaptations have made the desert isopod Hemilepistus reaumuri the most successful herbivore and detritivore of the macrofauna of many arid areas in North Africa and Asia Minor. For survival and reproduction Hemilepistus is dependent on burrows. New burrows can only be dug during spring. With the time-consuming digging of a burrow, Hemilepistus has only made the first step towards solving its ecological problems. The burrows are vital and have to be continuously defended against competitors. This requirement is met by co-operation of individuals within the framework of a highly developed social behaviour. In spring adults form monogamous pairs in which partners recognize each other individually and later form, with their progeny, strictly closed family communities. Hemilepistus is compared with a Porcellio' sp. which has developed, convergently, a social behaviour which resembles that of Hemilepistus in many respects, but differs essentially in some aspects, partly reflecting differences in ecological requirements. This and a few other Porcellio species demonstrate some possible steps in the evolution of the social behaviour of Hemilepistus. The female Hemilepistus is-in contrast to Porcellio sp. - semelparous and the selective advantages of monogamy in its environment are not difficult to recognize. This chapter discusses how this mating system could have evolved and especially why monogamous behaviour is also the best method for the Hemilepistus male to maximize its reproductive success. The cohesion of pairs and of family communities in Hemilepistus is based on a highly developed chemical communication system. Individual- and family-specific badges owe their specificity to genetically determined discriminating substances. The nature of the badges raises a series of questions: e.g. since alien badges release aggression, how do parents avoid cannibalizing their young? Similar problems arise from the fact that family badges are mixtures of chemical compounds of very low volatility with the consequence that they can only be transferred by direct contact and that during moulting all substances are lost which an individual does not produce itself. It is shown that in solving these problems inhibiting properties (presumably substances) and learning play a dominant role.
The Xiphophorus tumor system has provided the opportunity to reduce the enormous complexity of cancer etiology to a few biological elements basically involved in neoplasia. The development of a tumor requires an oncogene which, after impairment, deletion, or elimination of its regulatory genes is permitted to mediate neoplastic transformation. Emphasis is being placed today in cancer research on the actual oncogenes themselves, but, in our opinion, the most important genes involved in neoplasia are these regulatory genes. However, although detected by c1assical genetics in the Xiphophorus system, th ese genes are not at present open to a more fin ely detailed molecular biological analysis. Their actual mode of action is therefore still far from being understood.
Pseudotropheus hajomaylandi (loc. typ. Isle of Chisumulu, Lake Malawi) is described as a new species. It is compared with Ps. aurora, Ps. greshakei, Ps. livingstonii, Ps. lombardoi, and Ps. zebra. All these taxa, including Ps. hajomaylandi and Ps. heteropictus, are classified in the subgenus Maylandia.
No abstract available
The gene for the FeS protein of the Rhodopseudomonas sphaeroides b/c1 complex was identified by means of crosshybridization with a segment of the gene encoding the corresponding FeS protein of Neurospora crassa. Plasmids (pRSF1-14) containing the cross-hybridizing region, covering in total 13.5 kb of chromosomal DNA, were expressed in vitro in a homologous system. One RSF plasmid directed the synthesis of all three main polypeptides of the R. sphaeroides blc1 complex: the FeS protein, cytochrome b and cytochrome c1• The FeS protein and cytochrome c1 were apparently synthesized as precursor fonns. None of the pRSF plasmids directed the synthesis of the 10-kd polypeptide found in b/c1 complex preparations. Partial sequencing of the cloned region was performed. Several sites of strong homology between R. sphaeroides and eukaryotic polypeptides of the b/c1 complex were identified. The genes encode the three b/c1 polypeptides in the order: (5') FeS protein, cytochrome b, cytochrome c1• The three genes are transcribed to give a polycistronic mRNA of 2.9 kb. This transcriptional unit has been designated the jbc operon; its coding capacity corresponds to the size of the polycistronic mRNA assuming that only the genes for the FeS protein (jbcF), cytochrome b (jbcß) and cytochrome c1 (jbcC) are present. This could indicate that these three subunits constitute the minimal catalytic unit of the b/c1 complex from photosynthetic membranes.
The c, b and ö subunit genes of the Escherichia coli atp operon were cloned individually in an expression vector between the tac fusion promoter and the galK gene. The relative rates of subunit synthesis directed by the cloned genes were similar in vitro andin vivo and compared favourably with the subunit stoichiometry of the assembled proton-translocating A TP synthase of E. coli in vivo. The rate of synthesis of subunit c was at least six times that of subunit b and 18 times that of subunit ö. Progressive shortening of the long intercistronic sequence lying upstream of the subunit c gene showed that maximal expression of this gene is dependent upon the presence of a sequence stretching > 20 bp upstream of the Shine-Dalgarno site. This sequence thus acts to enhance the rate of translational initiation. The possibility that similar sequences might perform the same function in other operons of E. coli and bacteriophage A is also discussed. Translation of the subunit b cistron is partially coupled to translation of the preceding subunit c cistron. In conclusion, the expression of all the atp operon genes could be adjusted to accommodate the subunit requirements of A TP synthase assembly primarily by means of mechanisms which control the efficiency of translational initiation and re-initiation at the respective cistron start codons.
Isolation of a functional human interleukin 2 gene from a cosmid library by recombination in vivo
(1985)
A method has been developed that allows the isolation of genomic clones from a cosmid library by homologaus recombination in vivo. This method was used to isolate a human genomic interleukin 2 (IL2) gene. The genomic cosmid library was packaged in vivo into A. phage particles. A recombination-proficient host strain carrying IL2 cDNA sequences in a non-homologaus plasmid vector was infected by the packaged cosmid library. After in vivo packaging and reinfection, recombinants carrying the antibiotic resistance genes of both vectors were selected. From a recombinant cosmid clone the chromosomal IL2 genewas restored. After DNA mediated gene transfer into mouse Ltk- cells human IL2 was expressed constitutively.
Using a monoclonal antibody (No-194) we have identified, in Xenopus laevis and other amphibia, an acidic protein of M, 40,000 (ribocharin) which is specifically associated with the granular component of the nucleolus and nucleoplasmic 65S particles. These particles contain the nuclear 28S rRNA and apparently represent the precursor to the large ribosomal subunit in nucleocytoplasmic transit. By immunoelectron microscopy ribocharin has been localized in the granular component of the nucleolus and in interchromatin granules. During mitosis ribocharin-containing particles are associated with surfaces of chromosomes and are recollected in the reconstituting nucleoli in late telophase. We suggest that ribocharin is a specific component of precursor particles of the large ribosomal subunit, which dissociates from the 65S particle before passage through the nuclear envelope, and is reutilized in ribosome biogenesis.
Using antibodies to various nucleolar and ribosomal proteins, we define, by immunolocalization in situ, the distribution of nucleolar proteins in the different morphological nucleolar subcompartments. In the present study we describe the nucleolar localization of a specific ribosomal protein (51) by immunofluorescence and immunoelectron microscopy using a monoclonal antibody (R5 1-105). In immunoblotting experiments, this antibody reacts specifically with the largest and most acidic protein of the small ribosomal subunit (51) and shows wide interspecies cross-reactivity from amphibia to man. Beside its localization in cytoplasmic ribosomes, this protein is found to be specifically localized in the granular component of the nucleolus and in distinct granular aggregates scattered over the nucleoplasm. This indicates that ribosomal protein 51, in contrast to reports on other ribosomal proteins, is not bound to nascent pre-rRNA transcripts but attaches to preribosomes at later stages of rRNA processing and maturation. This protein is not detected in the residual nucleolar structures of cells inactive in rRNA synthesis such as amphibian and avian erythrocytes. During mitosis, the nucleolar material containing ribosomal protein 51 undergoes a remarkable transition and shows a distribution distinct from that of several other nucleolar proteins. In prophase, the nucleolus disintegrates and protein 51 appears in numerous small granules scattered throughout the prophase nucleus. During metaphase and anaphase, a considerable amount of this protein is found in association with the surfaces of all chromosomes and finely dispersed in the cell plasm. In telophase, protein 51-containing material reaccumulates in granular particles in the nucleoplasm of the newly formed nuclei and, finally, in the re-forming nucleoli. These observations indicate that the nucleolus-derived particles containing ribosomal protein 51 are different from cytoplasmic ribosomes and, in the living cell, are selectively recollected after mitosis into the newly formed nuclei and translocated into a specific nucleolar subcompartment, i.e ., the granular component. The nucleolar location of ribosomal protein 51 and its rearrangement du'ring mitosis is discussed in relation to the distribution of other nucleolar proteins.
Individual recogmtlon in the non-eusocial arthropods is, according to our present knowledge, predominantly found in the frame of permanent or temporary monogamy. In some cases, e. g. in stomatopods and possibly other marine crustaceans too, individual recognition may serve to allow identification of (i) individuals within dominance hierarchies or (ii) neighbours in territorial species thus helping to avoid the repetition of unnecessary and costly fights. Kin recognition is experimentally proven only in some isopod species (genera Hemilepistus and Porcel/io) and in the primitive cockroach (termite?) Cryptocercus. The «signatures» or «discriminators» used in the arthropods are chemical. It is assumed that the identifying substances are mainly genetically determined and in this paper I shall discuss possible evolutionary origins. The main part of this account is devoted to the presentation of some aspects of the highly developed individual and kin identification and recognition system in the desert isopod Hemilepistus reaumuri - a pure monogamous species in which pairs together with their progeny form strictly exclusive family units. Amongst other things problems of (i) mate choice, (ii) learning to recognize a partner, (iii) avoiding the un adaptive familiarization with aliens are treated. Monogamy under present conditions is for both sexes the only suitable way of maximizing reproductive success; an extremely strong selection pressure must act against every attempt to abandon monogamy under the given ecological conditions. The family «badges» which are certainly always blends of different discriminator substances are extremely variable. This variability is mainly due to genetical differences and is not environmentally caused. It is to be expected that intra-family variabiliry exists in respect of the production of discriminator substances. Since the common badge of a family is the result of exchanging and mixing individual substances, and since the chemical nature of these discriminators requires direct body contacts in order to acquire those substances which an individual does not produce itself, problems must arise with molting. These difficulties do indeed exist and they are aggravated by the fact that individuals may produce substances which do not show up in the common family badge. An efficient learning capability on the one hand and the use of inhibiting properties of newly molted isopods help to solve these problems. In the final discussion three questions are posed and - partly at least - answered; (i) why are families so strictly exclusive, (ii) how many discriminator substances have to be produced to provide a variability allowing families to remain exclusive under extreme conditions of very high population densities, (iii) what is the structure of the family badge and what does an individual have to learn apart from the badge in order not to mistake a family member for an alien or vice versa.
Activation of the pp60\(^{c-src}\) kinase during differentiation of monomyelocytic cells in vitro
(1986)
Tbe proto-oncogene c-src, the cellular homolog of the Rous sarcoma virus (RSV) transforming gene v-src, is expressed in a tissue-specific and age-dependent manner. Its physiological function, although still unknown, appears to be more closely related to differentiation processes than to proliferation processes. To obtain more information about the physiological role of the c-src gene in cells, we have studied differentiation-dependent alterations using the human HL-60 leukaemia cell line as a model system. Induction of monocytic and granulocytic differentiation of HL-60 cells by 12-0-tetradecanoylphorbol-13-acetate (TPA) and dimethylsulfoxide (DMSO) is associated with an activation of the pp60<sup>c-src</sup> tyrosine kinase, but not with increased c-src gene expression. Control experiments exclude an interaction of TPA and DMSO themselves with the pp60<sup>c-src</sup> kinase.
A cDNA clone of about 2500 basepairswas prepared from the human osteosarcoma cellline U-2 OS by hybridizing with a v-sis probe. Sequence analysis showed that this cDNA contains the coding region for the PDGF-B chain. Here we report that the mitogen secreted by these osteosarcoma cells contains the PDGF-B chain and is probably a homodimer of two B-chains.
Three F0 subunits and the F\(_1\) subunit P of the ATP synthase from Neurospora crassa were labeled with the lipophilic photoactivatable reagent 3-(trifluoromethyl)-3-(m-[\(^{125}\)I]iodophenyl)diazirine ([\(^{125}\)I]TID). In the proteolipid subunit which was the most heavily labeled polypeptide labeling was confmed to five residues at the NH2-terminus and five residues at the C-terminus ofthe protein. Labeling occurred at similar positions compared with the homologaus protein (subunit c) in the ATP synthase from Escherichia coli, indicating a similar structure of the proteolipid subunits in their respective organisms. The inhibitors oligomycin and dicyclohexylcarbodiimide did not change the pattern of accessible surface residues in the proteolipid, suggesting that neither inhibitor induces gross conformational changes. However, in the presence of oligomycin, the extent oflabeling in some residues was reduced. Apparently, these residues provide part of the binding site for the inhibitor. After reaction with dicyclohexylcarbodiimide an additional labeled amino acid was found at position 65 corresponding to the invariant carbodümide-binding glutamic acid. These results and previous observations indicate that the carboxyl side chain of Glu-65 is located at the protein-lipid interphase. The idea is discussed that proton translocation occurs at the interphase between different types if F\(_0\) subunits. Dicyclohexylcarbodiimide or oligomycin might disturb this essential interaction between the F\(_0\) subunits.
The structure of the F0 part of ATP synthases from E. coli and Neurospora crassa was analyzed by hydrophobic surface labeling with [125I]TID. In the E. co/i F0 all three subunits were freely accessible to the reagent, suggesting that these subunits are independently integrated in the membrane. Labeted amino acid residues were identified by Edman degradation of the dicyclohexylcarbodiimide binding (DCCD) proteins from E. coli and Neurospora crassa. The very similar patterns obtained with the two homologaus proteins suggested the existence of tightly packed cx-helices. The oligomeric structure of the DCCD binding protein appeared to be very rigid since little, if any, change in the labeling patternwas observed upon addition of oligomycin or DCCD to membranes from Neurospora crassa. When membrancs were pretrcated with DCCD prior to the reaction with [125I]TID an additionally labeled amino acid appeared at the position of Glu·65 which binds DCCD covalently, indicating the Jocation of this inhibitor on the outside of the oligomer. It is suggested that proton conduction occurs at the surface of the oligomer of the DCCD binding protein. Possibly this oligomer rotates against the subunit a or b and thus enables proton translocation. Conserved residues in subunit a, probably located in the Iipid bilayer, might participate in the pro· ton translocation mechanism.