Effect of social conditions during rearing on mating behaviour of gilts

The mating behaviour of 28 gilts was studied. The gilts were reared under two different social conditions known to affect both their puberty attainment and reproductive parameters during early pregnancy. The different social conditions were applied from an average age of 137 days onwards. Ten gilts were housed individually, having neither tactile nor visual contact with other pigs. The remaining gilts (n=18) were housed pairwise, having additional contact with gilts in adjacent pens and daily boar contact from 180 days of age onwards. At third oestrus, the gilts were artificially inseminated and subsequently introduced to one of three vasectomized boars for a period of 20 min. The gilts were slaughtered 10±1 days after insemination.

The mating behaviour varied considerably between individual gilts, partly because of differences in mating behaviour between the two groups of gilts. More (P<0.05) individually housed gilts showed a standing response latency upon introduction of the boar. During this latency period, the individually housed gilts initiated contact with the boar. Once the standing response was elicited, mating behaviour was similar in gilts of both social groups. One individually housed gilt did not show a standing response and consequently was not mated. The mating behaviour of the boars did not differ for the gilts of the two social conditions.

It was concluded that the social conditions of gilts during rearing affected their introductory sexual behaviour. The relationship with reproductive performance during early pregnancy is discussed.     

Myocardial S-adenosylhomocysteine hydrolase is important for adenosine production during normoxia

(1) The coronary vasodilator adenosine can be formed in the heart by breakdown of AMP or S-adenosylhomocysteine (SAdoHcy). The purpose of this study was to get insight into the relative importance of these routes of adenosine formation in both the normoxic and the ischemic heart. (2) A novel HPLC method was used to determine myocardial adenosine and SAdoHcy. Accumulation of SAdoHcy was induced in isolated rat hearts by perfusion with L-homocysteine thiolactone or L-homocysteine. The release of adenosine, inosine, hypoxanthine, xanthine and uric acid was determined. Additional in vitro experiments were performed to determine the kinteic parameters of S-adenosylhomocysteine hydrolase. (3) During normoxia the thiolactone caused a concentration-dependent increase in SAdoHcy. At 2000 μM of the thiolactone an SAdoHcy accumulation of 0.49 nmol/min per g wet weight was found during normoxia. L-Homocysteine (200 μM) caused an increased of 0.37 and 4.17 nmol SAdony/soc per g wet weight during normaxia and ischemia, respectively. (4) The adenosine concentration in ischemic hearts was significantly lower when homocysteine was infused (6.2 vs. 115 nmol/g; P < 0.05). Purine release was increased 4-fold during ischemia. (5) The K_m for hydrolysis of SAdoHcy was about 12 μM. At in vitro conditions favoring near-maximal SAdoHcy synthesis (72 μM adenosine, 1.8 mM homocysteine), the synthesis rate in homogenates was 10 nmol/min per g wet weight. (6) From the combined in vitro and perfusion studies, we comclude that S-adenosylhomocysteine hydrolase can contribute significantly to adenosine production in normoxic rat heart, but not during ischemia.     

Clinical and immunological evaluation of 20 patients with advanced colorectal cancer treated with high dose recombinant leukocyte interferon-αA (rIFNαA)

Summary A total of 20 patients with advanced colorectal cancer received recombinant leukocyte interferon-A (rIFNA) either chronically (group I: twice a week up to 20×10⁶ IU/m² i.m.) or cyclically (group II: 1–4 periods of 8 consecutive days up to 20×10⁶ IU/m² i.m. daily at 20-days intervals) over a period of 12 weeks. There was 1 partial response, 1 mixed response and 1 patient with stable disease, whilst 17 patients had progressive disease. Median survival was 15.5 months. Survival was significantly shorter when the extent of hepatic disease was >25% (P=0.05), extrahepatic disease was extensive (P<0.005), alkaline phosphatase level was >2× normal (P<0.02), or performance status was <100% (P<0.001). Toxicity consisting mainly of fever, fatigue, anorexia and weight loss was serious in group I and minimal in group II. Administration of rIFNA led to a short lived augmentation of natural killer (NK) cell activity. In the cyclically treated group this was a recurrent phenomenon whereas a marked lasting depression of NK cell activity was seen in chronically treated patients. Interferon- production capacity was significantly stimulated during rIFNA therapy. The differences in toxicity and immunostimulatory effects between the two schedules may be of importance in the design of further studies.This trial was supported in part by Hoffmann-La Roche, Basle     

Die Ausdifferenzierung des Vakuolensystems in Blüten- und Laubblattepidermen vonPrimula kewensis

Ohne Zusammenfassung     

Agrobacterium-mediated transformation of apple (Malus x domestica Borkh.): an assessment of factors affecting regeneration of transgenic plants

We have previously developed a protocol for efficient gene transfer and regeneration of transgenic calli following cocultivation of apple (cv. Jonagold) explants with Agrobacterium tumefaciens (De Bondt et al. 1994, Plant Cell Reports 13: 587–593). Now we report on the optimization of postcultivation conditions for efficient and reproducible regeneration of transgenic shoots from the apple cultivar Jonagold. Factors which were found to be essential for efficient shoot regeneration were the use of gelrite as a gelling agent and the use of the cytokinin-mimicing thidiazuron in the selective postcultivation medium. Improved transformation efficiencies were obtained by combining the hormones thidiazuron and zeatin and by using leaf explants from in vitro grown shoots not older than 4 weeks after multiplication. Attempts to use phosphinothricin acetyl transferase as a selectable marker were not successful. Using selection on kanamycin under optimal postcultivation conditions, about 2% of the leaf explants developed transgenic shoots or shoot clusters. The presence and expression of the transferred genes was verified by -glucuronidase assays and Southern analysis. The transformation procedure has also been succesfully applied to several other apple cultivars.Abbreviations BAP benzylaminopurine - CTAB hexadecyltrimethylammoniumbromide - Na₂EDTA ethylenediamine-tetra-acetate ferric-sodium salt - FeNaEDTA ethylenediamine-tetra-acetate ferric-sodium salt - GA₃ gibberellic acid 3 - GusA -glucuronidase - gusA -glucuronidase gene of Escherichia coli - IAA indole acetic acid - IBA indole butyric acid - 2iP N6-2-isopentenyl adenine - NAA naphthalene acetic acid - nptII neomycinphosphotransferase II gene - bar phosphinothricin acetyl transferase gene - PCR polymerase chain reaction - PPT phosphinothricin - STS silver thiosulphate - T-DNA transferred DNA - TDZ thidiazuron - X-Gluc 5-bromo-4-chloro-3-indolyl -D-glucuronide - Zea trans-Zeatin     

The C-terminal KDEL sequence increases the expression level of a single-chain antibody designed to be targeted to both the cytosol and the secretory pathway in transgenic tobacco

The effects of subcellular localization on single-chain antibody (scFv) expression levels in transgenic tobacco was evaluated using an scFv construct of a model antibody possessing different targeting signals. For translocation into the secretory pathway a secretory signal sequence preceded the scFv gene (scFv-S). For cytosolic expression the scFv antibody gene lacked such a signal sequence (scFv-C). Also, both constructs were provided with the endoplasmic reticulum (ER) retention signal KDEL (scFv-SK and scFv-CK, respectively). The expression of the different scFv constructs in transgenic tobacco plants was controlled by a CaMV 35S promoter with double enhancer. The scFv-S and scFv-SK antibody genes reached expression levels of 0.01% and 1% of the total soluble protein, respectively. Surprisingly, scFv-CK transformants showed considerable expression of up to 0.2% whereas scFv-C transformants did not show any accumulation of the scFv antibody. The differences in protein expression levels could not be explained by the steady-state levels of the mRNAs. Transient expression assays with leaf protoplasts confirmed these expression levels observed in transgenic plants, although the expression level of the scFv-S construct was higher. Furthermore, these assays showed that both the secretory signal and the ER retention signal were recognized in the plant cells. The scFv-CK protein was located intracellularly, presumably in the cytosol. The increase in scFv protein stability in the presence of the KDEL retention signal is discussed.     

Genetics of subtilin and nisin biosyntheses

Several peptide antibiotics have been described as potent inhibitors of bacterial growth. With respect to their biosynthesis, they can be devided into two classes: (i) those that are synthesized by a non-ribosomal mechanism and (ii) those that are ribosomally synthesized. Subtilin and nisin belong to the ribosomally synthesized peptide antibiotics. They contain the rare amino acids dehydroalanine, dehydrobutyrine, meso-lanthionine, and 3-methyl-lanthionine. They are derived from prepeptides which are post-translationally modiffied and have been termed lantibiotics because of their characteristic lanthionine bridges (Schnell et al. 1988). Nisin is the most prominent lantibiotic and is used as a food preservative due to its high potency against certain gram-positive bacteria (Mattick & Hirsch 1944, 1947; Rayman & Hurst 1984). It is produced by Lactococcus lactis strains belonging to serological group N. The potent bactericidal activities of nisin and other lantibiotics are based on depolarization of energized bacterial cytoplasmic membranes. Breakdown of the membrane potential is initiated by the formation of pores through which molecules of low molecular weight are released. A trans-negative membrane potential of 50 to 100 mV is necessary for pore formation by nisin (Ruhr & Sahl 1985; Sahl et al. 1987). Nisin occurs as a partially amphiphilic molecule (Van de Ven et al. 1991). Apart from the detergent-like effect of nisin on cytoplasmic membranes, an inhibition of murein synthesis has also been discussed as the primary effect (Reisinger et al. 1980). In several countries nisin is used to prevent the growth of clostridia in cheese and canned food. The nisin peptide structure was first described by Gross & Morall (1971), and its structural gene was isolated in 1988 (Buchman et al. 1988; Kaletta & Entian 1989). Nisin has two natural variants, nisin A and nisin Z, which differ in a single amino acid residue at position 27 (histidin in nisin A is replaced by asparagin in nisin Z (Mulders et al. 1991; De Vos et al. 1993). Subtilin is produced by Bacillus subtilis ATCC 6633. Its chemical structure was first unravelled by Gross & Kiltz (1973) and its structural gene was isolated in 1988 (Banerjee & Hansen 1988). Subtilin shares strong similarities to nisin with an identical organization of the lanthionine ring structures (Fig. 1), and both lantibiotics possess similar antibiotic activities. Due to its easy genetic analysis B. subtilis became a very suitable model organism for the identification and characterization of genes and proteins involved in lantibiotic biosynthesis. The pathway by which nisin is produced is very similar to that of subtilin, and the proteins involved share significant homologies over the entire proteins (for review see also De Vos et al. 1995b). The respective genes have been identified adjacent to the structural genes, and are organized in operon-like structures (Fig. 2). These genes are responsible for post-translational modification, transport of the modified prepeptide, proteolytic cleavage, and immunity which prevents toxic effects on the producing bacterium. In addition to this, biosynthesis of subtilin and nisin is strongly regulated by a two-component regulatory system which consists of a histidin kinase and a response regulator protein.