Habitatwahl beim Neunt?terLanius collurio

Zusammenfassung Im Bereich des Meßtischblattes Bad Wildungen (MTB 4820; grundlegende DatenMann 1983,Lübcke &Mann 1984) bevorzugt der Neuntöter Viehweiden (Abb. 3). Reviere an Viehweiden zeigen eine längere kontinuierliche Besetzungszeit (Abb. 4) im Vergleich zu anderen Nutzungsformen. Die Anzahl flügger Jungvögel ist in Viehweiderevieren größer im Gegensatz zu Revieren an Mähwiesen oder Brachflächen (Abb. 5). Dieser Unterschied des Reproduktionserfolges liegt nicht an unterschiedlichen Nahrungsdichten (Abb. 6), sondern an der besseren Zugänglichkeit.

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Habitat selection in the Red-backed ShrikeLanius collurio

Summary In the area of Bad Wildungen (FRG; Hessia; MTB 4820; basic data inMann 1983,Lübcke &Mann 1984) the Red-backed Shrike selects for pastures (Abb. 3). Territories at pastures show a longer continual occupation in comparison to other land use systems (Abb. 4). The number of fledgelings is higher at pastures in comparison to meadows or fallow land (Abb. 5). This difference is not caused by higher insect densities (Abb. 6) but by better accessible prey due to permanent low vegetation at pastures.

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Reihenfolge alphabetisch und umgekehrt proportional zur geleisteten Arbeit: R. B. Auswertung, W. L. & W. M. Kartierung, W. M. Brut- und Nahrungsbiologie. Sonderdruckanforderungen an R. B.     

Initiation and development of wound tissue and roots on hypocotyl cuttings of Pinus sylvestris in vitro

The rooting of hypocotyl cuttings from 20-day-old seedlings of Pinus sylvestris L. cultured in vitro is discussed. About 40% of the cuttings cultured on medium lacking activated charcoal produced roots during the first two months. When activated charcoal was added to the medium, either root formation (75% formed roots) or wound tissue growth (95% formed large wound tissues) was stimulated in different experiments. These large wound tissues did not develop any roots. The anatomical changes in the basal part of the cuttings were similar during the first two weeks in all the cuttings studied. A vascular cylinder composed of short tracheids with many pores developed. Thereafter the differentiation process became varied. The amount of wound tissue produced and the time for rooting differed among the cuttings. Tracheid nests which were in contact with the vascular system in the hypocotyl via short tracheids were observed after three weeks. Subsequently, roots developed from the tracheid nests. The longer root formation was delayed, the larger the wound tissue became.
Short tracheids were found close to the wound tissue surface. Their ability to adsorb nutrients and water is discussed.     

Differentiation patterns in the Scutellaria albida group (Lamiaceae) in the Aegean area

An experimental investigation of the mainly white-flowered Scutellaria albida group in the Aegean area was carried out. Eight populations representing maximum morphological variation as well as geographic separation were chosen for crosses between populations. Strong sterility barriers were observed in the Cretean endemic species, S. sieberi Benth., which also deviated morphologically and is probably an ancient relic. Strong crossing barriers were also found in plants from Euboea, and, in spite of little morphological differentiation from S. albida L. s. str., they are treated as a separate species, S. goulimyi Rech. fil. Crossing barriers of intermediate strength were present in morphologically distinct material from N Sporades, which is also treated as a separate species, S. sporadum Bothmer sp. nov. All other populations showed high compatibility in crosses among themselves, viz. populations from Bulgaria, Thrace, Andros, Naxos, and Rodhos. These were treated as the same species, S. albida , having large local as well as clinal variation. Three subspecies are retained: ssp. albida in the north; ssp. perhispida (Bornm.) Bothmer in E Macedonia, Thrace and on the islands; and the mainly purple-flowered, ssp. vacillans (Rech. fil.) Bothmer, endemic to the peninsula of Athos. Evolutionary pathways and phytogeographical patterns are discussed.
S. sporadum is mainly inbreeding and, in S. sieberi , indications of a self-incompatibility system were found. The other taxa have a more versatile system.     

Generation of nonspecific murine cytotoxic T cells in vitro by purified human interleukin 2

Murine spleen cells developed into nonspecific cytotoxic cells within 72 hr of culture in the presence of highly purified sources of human interleukin 2. In whole spleen cell cultures, human interleukin 2 generated effector cells which were Thy 1.2⁺, Lyt 2.2⁺, resistant to γ irradiation (1000 R), and capable of lysing both H-2 compatible and incompatible targets. The effector cells generated in this manner were not restricted to classical natural killer cell-sensitive targets. If thymus-derived cells (T cells) were depleted from the spleen cell population before culture with human interleukin 2, the effector cells generated were enriched in effectors capable of lysing natural killer cell-sensitive targets. Interferon was not produced in interleukin 2-stimulated spleen cell cultures. In addition, heterologous antibody to murine -γ-interferon did not abrogate the generation of cytotoxic cells by human interleukin 2. These and additional data suggest that human interleukin 2 is capable of stimulating γ-irradiation-sensitive Thy 1.2⁺ cell(s) capable of lysing a variety of target cells regardless of inherent sensitivities to classical natural killer cells. Thy 1.2^? cells were also stimulated by human interleukin 2 and lysed only natural killer cell-sensitive targets. Human interleukin 2 caused some Thy 1.2^? cells to become susceptible to lysis by anti-Thy 1.2 serum and complement.     

Identification of two types of keratin polypeptides within the acidic cytokeratin subfamily I

Cytoskeletal filaments of the α-keratin type (cytokeratins) are a characteristic of epithelial cells. In diverse mammals (man, cow and rodents) these cytokeratins consist of a family of approximately 20 polypeptides, which may be divided into the more acidic (I) and the more basic (II) subfamilies. These two subfamilies show only limited amino acid sequence homology. In contrast, nucleic acid hybridization experiments and peptide maps have been interpreted to show that polypeptides of the same subfamily share extended sequence homology.We compare two polypeptides of the acidic cytokeratin subfamily, VIb (M_r 54,000) and VII (M_r 50,000), which are co-expressed in large amounts in bovine epidermal keratinocytes. These two epidermal keratins can be distinguished by specific antibodies and show different patterns of expression among several bovine tissues and cultured cells. In addition, they differ in the stability of their complexes with basic keratin polypeptides and in their tryptic peptide maps. The amino acid sequences deduced from the nucleotide sequences of complementary DNA clones containing the 3′ ends of the messenger RNAs for these keratins are compared with each other and with available amino acid sequences of human, murine and amphibian epidermal keratins. Bovine keratins VIb and VII share considerable sequence homology in the α-helical portion (68% residues identical) but lack significant homology in the extrahelical portion. Bovine keratin VIb shows, in its α-helical region, a pronounced sequence homology (88% identity) to the murine epidermal keratin of M_r 59,000. In addition, the non-helical carboxy-terminal regions of both proteins are glycinerich and contain a canonic sequence GGG^S_GYGG, which may be repeated several times. Moreover, their mRNAs present a highly conserved stretch of 236 nucleotides containing, in the murine sequence, the end of the coding and all of the non-coding region (81% identical nucleotides). Bovine keratin VII is considerably different from the murine M_r 59,000 keratin but is almost identical to the human cytokeratin number 14 of M_r 50,000, both in the α-helical and in the non-α-helical regions of the proteins, and the mRNAs of the human and the bovine keratins also display a high homology in their 3′ non-coding ends.The results show that in the same species keratins of the same subfamily can differ considerably, whereas equivalent keratin polypeptides of different species are readily identified by characteristic sequence homologies in the α-helical and the non-helical regions as well as in the 3′ non-coding portions of their mRNAs. Among the members of the acidic subfamily I of cytokeratin polypeptides that are co-expressed in bovine epidermis, at least two types can be distinguished by their carboxy-terminal sequences. One type is characterized by its abundance of glycine residues, a consensus GGG^S_GYGG heptapeptide sequence, which may be repeated several times, and an extended stretch of high RNA sequence homology in the 3′ non-coding part. The other type shows a predominance of serine and valine residues, a subterminal GGG^S_GYGG sequence (which has been maintained in Xenopus, cow and man) and also a high level of homology in the 3′ non-coding part of the mRNA. The data indicate that individual keratin type specificity overrides species diversity, both at the protein and the mRNA level. We discuss the evolutionary conservation and the tissue distribution of these two types of acidic keratin polypeptides as well as their possible biological functions.     

Structure of the segmentation gene paired and the Drosophila PRD gene set as part of a gene network

The sequence of paired, a pair-rule gene required for segmentation in Drosophila, is presented. A search for genes with domains homologous to the paired gene was initiated and three homologues from a set of 12 were characterized with respect to temporal or spatial expression and sequence homologies. All four are transcribed in early development, one in the oocyte and during cleavage stages in the form of a gradient. In addition to the prd-specific his-pro repeat, some of the 12 genes contain M-repeats and two new types of homeo boxes not detectable by hybridization with the two known classes of homeo boxes. The observed linking of gene sets through combinations of homologies coding for protein domains is consistent with a general network concept of gene action.     

Sex-dependent effects of non-H-2 loci on lethal GVH reaction induced across an H-2 barrier

We have studied the influence of DBA/2 non-H-2 antigens on the lethal graft-versus-host reaction (GVHR) developed across an H-2 barrier. (DBA/2 x B10.D2)F₁ x B10.D2 (H-2 ^d) backcross (BC) mice were typed for their allelic constitution at nine genetically independent chromosome markers and used as individual cell donors simultaneously for two to three (DBA/2 X B10.D2)F₁ recipients incompatible for DBA/2 non-H-2 antigens alone and two to three (DBA/2 x B10.BR)F₁ recipients incompatible for DBA/2 non-H-2 antigens and H-2^k. The results showed that, when compared with that developed in a control group incompatible for H-2 ^kalone [B10.D2(B10.D2xB10.BR)F₁], the GVHR mortality seen in the presence of an additional incompatibility for DBA/2 non-H-2 antigens [(DBA/2 X B10.BR)F₁recipients] is significantly delayed but only in female mice. An analysis of individual BC donors indicated that this protective effect of DBA/2 non-H-2 antigens correlates with incompatibility for gene(s) linked to the Pgm-1 chromosome marker. In contrast, incompatibility for gene(s) linked to Mod-1 and Es-3 markers accelerates GVHR mortality, but only in male mice. Finally, the results obtained with (DBA/2 x B10.D2)F₁ and (DBA/2 x B10.BR)F₁ recipients were compared; they showed that the intensity of the GVHR developed by cells from individual BC donors against a given set of DBA/2 non-H-2 antigens correlates well with that developed by the same BC donor against the same set of non-H-2 antigens plus H-2^k. We conclude that certain non-H-2 genes (and antigens) can modulate the intensity of the GVHR developed across an H-2 barrier. The number of such genes is probably great; their effects are strong and complex, and can be sex-dependent.     

Electrorotation of lymphocytes—The influence of membrane events and nucleus

Electrorotation—the spin of cells in rotating high frequency electric fields—has been used to investigate properties of human peripheral blood lymphocytes. The rotation spectra of lymphocytes deviate from those of single shell spheres. The deviations are caused by the electrical properties of the nucleus in the cell interior.Electrorotation allows the distinction between successfully stimulated lymphocytes and unstimulated cells after application of concanavalin A. Notwithstanding the fact that only a proportion of the cells will be mitogenically stimulated we detected an enhanced cell membrane conductivity for the whole cell population immediately after the addition of mitogen.     

In vitro studies on the subcellular location of glucosidase I and glucosidase II in dog pancreas

When programmed with yeast prepro--factor mRNA, the heterologous reticulocyte/dog pancreas translation system synthesizes two pheromone related polypeptides, a cytosolically located primary translation product (pp--F_cyt, 21 kDa) and a membrane-specific and multiply glycosylated e-factor precursor (pp--F₃, 27.5 kDa). Glycosylation of the membrane specific pp--F₃ species is competitively inhibited by synthetic peptides containing the consensus sequence Asn-Xaa-Thr as indicated by a shift of its molecular mass from 27.5 kDa to about 19.5 kDa (pp--F₀) , whereas the primary translation product pp--Fcyt is not affected. Likewise, only the glycosylated pp--F₃ structure is digested by Endo H yielding a polypeptide with a molecular mass between PP--F₀ and pp--Fcyt. These observations strongly suggest that the primary translation product is proteolytically processed during/on its translocation into the lumen of the microsomal vesicles. We believe that this proteolytic processing is due to the cleavage of a signal sequence from the pp--Fcyt species, although this interpretation contradicts previous data from other groups. The distinct effect exerted by various glycosidase inhibitors (e.g. 1-deoxynojirimycin, N-methyl-dNM, 1-deoxymannojirimycin) on the electrophoretic mobility of the pp--F₃ polypeptide indicates that its oligosaccharide chains are processed to presumbly Man₉-GlcNAc₂ structures under thein vitro conditions of translation. This oligosaccharide processing is most likely to involve the action of glucosidase I and glucosidase II as follows from the specificity of the glycosidase inhibitors applied and the differences of the molecular mass observed in their presence. In addition, several arguments suggest that both trimming enzymes are located in the lumen of the microsomal vesicles derived from endoplasmic reticulum membranes.Abbreviations dNM 1-deoxynojirimycin - N-Me-dNM N-methyl-dNM - dMM 1-deoxymannojirimycin - CCCP carbonylcyanide m-chlorophenyl hydrazone