Comparison of genetic behaviour of the transposable element Tam3 at two unlinked pigment loci in Antirrhinum majus

Summary In Antirrhinum majus the transposable element Tam3 has been described at two unlinked loci pallida and nivea, both of which are required for the production of anthocyanin pigment in flowers. In each case the element is inserted in the promoter region and gives a variegated phenotype. We show that the rate of Tam3 excision at both loci is greatly affected by temperature, being approximately 1000-fold higher at 15°C compared with 25°C. Tam3 is also controlled by an unlinked gene Stabiliser, which considerably reduces excision rate. We show that the high degree of sensitivity to temperature and Stabiliser is an intrinsic property of Tam3 which is not shared by an unrelated element, Tam1. The Tam3 insertion at nivea gives rise to a series of alleles which confer reduced pigmentation, novel spatial patterns and changed instability. These are probably a result of imprecise excision and rearrangements of the Tam3 element.     

Combination treatment using thymosin α1 and interferon after cyclophosphamide is able to cure Lewis lung carcinoma in mice

Summary A combination treatment with thymosin 1 (200 µg/kg) for 4 days, followed by a single injection of murine interferon / (3 × 10⁴ international units/mouse), starting 2 days after cyclophosphamide treatment (200 mg/kg, single injection) demonstrated a dramatic and rapid disappearance of tumor burden in mice bearing Lewis lung carcinoma (3LL) tumor. The effectiveness of this new chemoimmunotherapy protocol was evident even on the long-term survival in a high percentage of animals, and was statistically significant when compared to treatment with the single agents in conjunction with chemotherapy or to chemotherapy itself. The same combination immunotherapy treatment strongly stimulated natural killer activity and cytotoxicity against autologus 3LL tumor cells in 3LL-tumor-bearing mice treated with cyclophosphamide, whereas treatments with each agent singly did not alter or only slightly modified the cytotoxic activity towards Yac-1 or 3LL target cells. Selective depletion with antibodies showed that killer cells stimulated by combination chemoimmunotherapy treatment bear phenotypic characteristics of asialo-GM1-positive cells. A histological study has shown a high number of infiltrating lymphoid cells in the tumors obtained from mice treated with combination chemoimmunotherapy.     

Anisotropy decay of fluorescence as an experimental approach to protein dynamics

This minireview makes an initial assessment of the progress made using anisotropy decay measurements for investigating the conformational changes and molecular dynamics in soluble systems. A critical analysis of available data is presented. The anisotropy decays of the tryptophan fluorescence of staphylococcal nuclease, adrenocorticotropin, melittin and of labeled transfer RNA were studied for investigating the functional conformational changes of these systems. The emissions of variously labeled immunoglobulins have been used to elucidate the conformations of these proteins before and after the binding of specific antibodies. Labeled myosin and its fragments have given information on the functional motions of the protein domains. The anisotropy decays of labeled and natural hemoglobin systems have been utilized for exploring the allosteric behavior of these molecules. The data suggest a wide applicability of this technique to the study of protein dynamics and conformational changes of macromolecules.     

Plasmids in toxic and nontoxic strains of the cyanobacteriumMicrocystis aeruginosa

The plasmid content and toxicity of nine different strains ofMicrocystis aeruginosa have been analyzed. The two toxic strains of the HUB Culture Collection were found to carry each two plasmids, pMA1 and pMA2, of 2.9 kb and 8.5 kb, respectively. In strains PCC 7813 and PCC 7820, also toxic, two different plasmids of 2.6 kb and 16 kb were detected. Hybridization experiments showed that there exists no sequence homology between the pMA plasmids and the plasmids found in the PCC strains; but the pMA plasmids hybridized to chromosomal DNA of the toxic strains PCC 7820, PCC 7813, HUB 063, and the nontoxic strain HUB 5-3. In nontoxic strains no or at most one plasmid of unstable occurrence could be detected. Only one of the toxic strains investigated, SAG 14.85 (NRC-1), contained no plasmid.     

Effect of relaxin on facilitation of parturition in dairy heifers

Purified pig relaxin (3000 U/mg) was injected i.m. into pregnant Holstein dairy heifers on Day 276 or 277 to determine its effect on parturition and sequential measurements of the pelvic area, cervical dilatation, and peripheral blood-plasma concentrations of progesterone and relaxin. Treatments included phosphate-buffer saline (2 ml, Group C, N = 7), relaxin once (1 mg, Group 1R, N = 7), and twice (2 mg, 12 h apart; Group 2R, N = 7). Intervals (mean +/- s.e.) between the first injection of relaxin or PBS and calving were 64 +/- 17, 80 +/- 19 and 125 +/- 34 h for Groups 2R, 1R and C, respectively. The calving intervals were reduced in Groups 2R (P less than 0.01) and 1R (P less than 0.05) compared with Group C. The incidence of dystocia was 29% (2 of 7) in Group 2R and 43% (3 of 7) in Group 1R compared with 57% (4 of 7) in Group C (P less than 0.01). Body weights and ratios of males to females of the calves were similar (P greater than 0.05) between groups. Progesterone plasma concentrations decreased (P less than 0.01) earlier in Groups 1R and 2R compared with Group C, and this acute decrease began within 6 h of treatment. At 24 h after relaxin or PBS injection, progesterone concentrations were 2.7 +/- 1.1 ng/ml for Group 2R, 3.5 +/- 0.9 ng/ml for Group 1R, and 6.0 +/- 0.1 ng/ml for Group C. Relaxin reached peak blood-plasma levels of 19 +/- 2.2 ng/ml 1 h after injection of relaxin, but remained unchanged, 0.3 +/- 0.01 ng/ml, in Group C. Pelvic area was increased 26%, 22% and 14% and cervical dilatation was increased 109%, 76% and 53% 48 h after injection in Groups 2R, 1R and C, respectively, but these responses were similar among groups at the time of parturition. We conclude that two i.m. injections of relaxin facilitated earlier calving, acutely decreased progesterone secretion, increased cervical dilatation and pelvic area expansion, and decreased the incidence of dystocia in dairy heifers.     

Purification from human pregnancy serum of a low molecular weight mitogen similar to placental lactogen and growth hormone

Recently, we isolated from the serum of pregnant women a factor that induced rapid proliferation of a lactogen-dependent rat lymphoma cell line (Nb2). This mitogenic factor is reasonably specific to pregnancy, since it was present in serum samples from second trimester as well as term-pregnant women, but not in those of adult men or cycling females. It is unlikely that this mitogenic activity (referred to as pregnancy mitogen [PM]) is due to contamination by classical lactogens, since acetone fractionation of serum yielded a preparation devoid of placental lactogen and prolactin, as determined by radioimmunoassays. Further purification of acetone precipitates from term-pregnant serum by ion exchange chromatography and gel filtration yielded a mitogenic activity with a relative mol wt of approximately 10,000. PM activity in the NB2 cell bioassay was not affected by the presence of prolactin antiserum. However, its activity was immunoneutralized by coincubation with anti-placental lactogen serum and, to a lesser extent, anti-growth hormone serum. It appears that PM was not generated by our extraction procedure, since gel filtration of whole serum also yielded a bioactive fraction of approximately 10 kDa. PM was further purified to homogeneity by high-performance liquid chromatography. Examination of the preliminary amino acid composition of PM revealed differences from that of a bioactive fragment of growth hormone and a corresponding portion of placental lactogen, suggesting that PM could be either a molecular variant of these hormones or a novel protein.     

Species dispersion profiles of anthropogenic grasslands in the Italian Eastern Pre-Alps

A method is proposed to analyse the dispersion profiles of species in classes of environmental variables, based on the decomposition of the expected frequencies in contingency tables with many interacting species. The method has been applied to data of dominant or very frequent graminoid species in grasslands of the Natisone Valley (Friuli, Italy). It allowed to make predictions by removing the random component of variation.Nomenclature follows: P. Zangheri (1976). Flora Italica, CEDAM, Padua.The authors were recipients of an Italian CNR grant (E. Feoli) and a Canadian NSERC grant (L. Orlóci) during tenure of this project. The results are in partial fulfillment of a commitment to the Centro Regionale per la Sperimentazione Agraria per il Friuli-Venezia Giulia.