Heterogeneity of ovine prolactin after labeling with iodine 125: value of labeling with lactoperoxidase]

The authors have shown an heterogeneity of the ovine prolactine molecule after labelling with iodine 125. As well with chloramine T as with lactoperoxydase, it appears three molecular species which react with the immune serum antiprolactine (I.S.). The first species is of high molecular weight and is probably constituted of aggregates. Their combination with the I.S. is non specific and give blanks of high value. The second species is a dimere and the third one is the monomere. The two last species react with the I.S. and can give competition curves when they are choosen as tracer. However, if one uses as tracer a product obtained by labelling with chloramine T, the competition appears for high concentrations of native hormone. As if the I.S. recognizes much more the labelled protein than the native one. But if one uses the same species but labelled with lactoperoxydase, the competition appears for concentrations lower than five nanogrammes. In the same time one can see that the specificity toward different I.S. is modified. The authors think that the labelling with lactoperoxydase better preserves the tertiary structure of the native protein than do the labelling with chloramine T.     

Differential distribution of cytokeratins after microinjection of anti-cytokeratin monoclonal antibodies

In order to investigate the relationship of different cytokeratins within one cell, monoclonal antibodies directed against three trophectoderm cytokeratins TROMA 1, 2 and 3 were microinjected into mouse teratocarcinoma-derived trophoblastoma cells and indirect immunofluorescence tests were used to follow the subsequent localization of their respective antigens Endo A, B and C. Microinjection of TROMA 1 or 2 resulted in the perinuclear collapse of Endo A, B and C-containing filaments. Microinjection of TROMA 3 resulted in the perinuclear collapse of filaments containing Endo A and B, whereas Endo C condensed into cytoplasmic aggregates which appear as speckles in the fluorescence microscope. The speckles were electron microscopically located using indirect gold-labeling techniques and had a dense, granulous structure. They were often found to be associated with microtubules, although colchicine treatment before microinjection did not interfere with speckle formation. These experiments demonstrate that cytokeratins can become differentially distributed within the cytoplasm after microinjection of an anti-cytokeratin monoclonal antibody. Since Endo A is a type II cytokeratin and Endo B and C are type I cytokeratins, these results suggest that different members of one cytokeratin subfamily may be associated with cytokeratin filaments which have different functions within the same cell.     

Regulation of sucrose-sucrose-fructosyltransferase in barley leaves

The activity of sucrose-sucrose-fructosyltransferase (SST), a vacuolar enzyme strongly induced by light in excised leaves of barley (Hordeum vulgare L.), rapidly declined even in continuous light upon feeding of cycloheximide (CHI). The rate of decline was similar to that observed in light-treated leaves that were placed into darkness, in the presence or absence of CHI. The protease inhibitor leupeptin totally stopped the decline in SST activity in the dark and caused a substantial increase in the rate of induction of SST activity by light. Feeding of sucrose prevented or even reversed the SST activity decay induced by darkness in the absence of CHI but did not stabilize SST activity in the presence of CHI. The results suggest that SST is continuously subjected to rapid, constant proteolytic degradation in the vacuole, and that the enhancement of SST activity in the light or upon feeding sucrose in the dark is due exclusively to de novo protein synthesis.     

Oviposition deterring pheromone in Rhagoletis cerasi: Behavioral laboratory test to measure pheromone activity

Current investigations concerning the identification of the chemical nature of the oviposition deterring pheromone of the European cherry fruit fly, Rhagoletis cerasi L., are conducted in an interdisciplinary research program by combining chemistry with behavioral evaluation. The methods used to collect and evaluate the pheromone by an improved semi-quantitative behavior test are described.

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Zusammenfassung Nach einer einleitenden Übersicht über den heutigen Stand der Erkenntnisse auf dem Gebiet der eiablage-hemmenden Pheromone (ODP) bei Fruchtfliegen und insbesondere der Kirschenfliege wird der verbesserte Verhaltenstest beschrieben, welcher für den halb-quantitativen Nachweis von ODP-Aktivität entwickelt worden ist. Im laufenden interdisziplinären Forschungsprogramm an der Eidg. Forschungsanstalt Wädenswil wird versucht, durch enge Zusammenarbeit zwischen Biologe, Chemiker und Elektrophysiologe das ODP der Kirschenfliege möglichst mit geringem Anteil an Verunreinigung einzusammeln, zu reinigen und einer chemischen Identifikation der ODP Komponenten zugänglich zu machen.Die Möglichkeiten und Grenzen des Verhaltenstests werden diskutiert und die Empfindlichkeit des Verfahrens mittels einer Konzentrationsreihe von Pheromonextrakt aufgezeigt.

     

Association between coated vesicles and microtubules

In this study, a possible functional association between microtubules and coated vesicles is described. We have found that our preparations of microtubules contained coated vesicles in quantities of usually above 10%. These coated vesicles were identified both by immunological methods using anticoat antibodies and by electron microscopy of negatively stained specimens. In the immune replica, two components of coated vesicles, i.e., heavy (clathrin) and light chains, were recognized as constituents of the preparations. In the electron microscope, it was found that coated vesicles were attached predominantly along the length of microtubules. Furthermore, projections from the microtubules to the triskelion centers of the clathrin lattice were identified and thus seem to serve as linkers between the cytoskeletal structure of the organelle. A similar type of association was detected in tissue culture cells; bridges between coated vesicles and microtubules were clearly identified by electron microscopy of thin sections.     

Patterns of sequence variation in the mitochondrial D-loop region of shrews

Direct sequencing of the mitochondrial displacement loop (D-loop) of shrews (genus Sorex) for the region between the tRNA(Pro) and the conserved sequence block-F revealed variable numbers of 79-bp tandem repeats. These repeats were found in all 19 individuals sequenced, representing three subspecies and one closely related species of the masked shrew group (Sorex cinereus cinereus, S. c. miscix, S. c. acadicus, and S. haydeni) and an outgroup, the pygmy shrew (S. hoyi). Each specimen also possessed an adjacent 76-bp imperfect copy of the tandem repeats. One individual was heteroplasmic for length variants consisting of five and seven copies of the 79-bp tandem repeat. The sequence of the repeats is conducive to the formation of secondary structure. A termination-associated sequence is present in each of the repeats and in a unique sequence region 5' to the tandem array as well. Mean genetic distance between the masked shrew taxa and the pygmy shrew was calculated separately for the unique sequence region, one of the tandem repeats, the imperfect repeat, and these three regions combined. The unique sequence region evolved more rapidly than the tandem repeats or the imperfect repeat. The small genetic distance between pairs of tandem repeats within an individual is consistent with a model of concerted evolution. Repeats are apparently duplicated and lost at a high rate, which tends to homogenize the tandem array. The rate of D- loop sequence divergence between the masked and pygmy shrews is estimated to be 15%-20%/Myr, the highest rate observed in D-loops of mammals. Rapid sequence evolution in shrews may be due either to their high metabolic rate and short generation time or to the presence of variable numbers of tandem repeats.      

大鼠胼胝体内神经肽Y免疫反应阳性纤维的发育

本实验用免疫组织化学ＡＢＣ法研究了大鼠胼胝体内神经肽Ｙ免疫反应阳性（ＮＰＹ－ＩＲ）纤维的生后发育。结果发现,许多ＮＰＹ－ＩＲ纤维在大鼠出生时便存在于胼胝体内。ＮＰＹ－ＩＲ胼胝体纤维的密度在生后１周内继续逐渐增高,在第２周内达到最高峰。之后,ＮＰＹ－ＩＲ胼胝体纤维的密度逐渐下降,至第３周末时接近成年时的水平,即仅有少量ＮＰＹ－ＩＲ纤维存在于胼胝体内。这些结果提示在大鼠早期生后发育过程中许多ＮＰＹ－ＩＲ胼胝体纤维是暂时性的,其作用可能与大脑皮质的机能发育有关。     

Ethylene: Symptom, Not Signal for the Induction of Chitinase and beta-1,3-Glucanase in Pea Pods by Pathogens and Elicitors

Infection of immature pea pods with Fusarium solani f.sp. phaseoli (a non-pathogen of peas) or f.sp. pisi (a pea pathogen) resulted in induction of chitinase and β-1,3-glucanase. Within 30 hours, activities of the two enzymes increased 9-fold and 4-fold, respectively. Chitinase and β-1,3-glucanase were also induced by autoclaved spores of the two F. solani strains and by the known elicitors of phytoalexins in pea pods, cadmium ions, actinomycin D, and chitosan. Furthermore, exogenously applied ethylene caused an increase of chitinase and β-1,3-glucanase in uninfected pods. Fungal infection or treatment with elicitors strongly increased ethylene production by immature pea pods. Infected or elicitor-treated pea pods were incubated with aminoethoxyvinylglycine, a specific inhibitor of ethylene biosynthesis. This lowered stress ethylene production to or below the level of uninfected controls; however, chitinase and β-1,3-glucanase were still strongly induced. It is concluded that ethylene and fungal infection or elicitors are separate, independent signals for the induction of chitinase and β-1,3-glucanase.