Integration and excision of pMC7105 in Pseudomonas syringae pv. phaseolicola: involvement of repetitive sequences.

The site for integration of pMC7105 into the chromosome of Pseudomonas syringae pv. phaseolicola has been mapped to a 2.6-kilobase-pair (kb) Bg/II-EcoRI fragment on this 150-kb indigenous plasmid. Selected excision plasmids resulting from imprecise excision of pMC7105 were used to identify one of the plasmid-chromosome juncture fragments and to characterize the mechanism of recombination from the chromosome. A 14.2-kb BamHI plasmid-chromosome juncture fragment has been identified in pEX8060 (234 kb), an excision plasmid which carries approximately 90 kb of chromosomal sequences to the left of the site of integration. This fragment contains a portion of the 2.6-kb Bg/II-EcoRI fragment as well as chromosomal sequences. Blot hybridization with a probe made from selected fragments of pMC7105 revealed three distinct repetitive sequences, RS-I, RS-II, and RS-III, on this plasmid. The 2.6-kb fragment, to which the site of integration maps, also contains RS-II. Five copies of RS-II are present in pMC7105, and more than 20 copies are present in the chromosome. Eight small excision plasmids were shown to result from recombination among fragments of pMC7105 that contain common repetitive sequences. The results indicate that integration and excision of pMC7105 occur through general recombination at homologous repetitive sequences.     

Phytosociological characteristics of theRondeletio correifoliae-Andropogonetum multinervosi ass. nova (Sierra de la Siguanea,Isla de la Juventud,Cuba)

The contribution deals with the phytocenological analysis of theRondeletio correifoliae-Andropogonetum multinervosi, an endemic savanna association occuring on the Siguanea Hills (Sierra de la Siguanea) near the Colony Hotel.     

The Electrical Conductivity of Bovine Milk in Mastitis Diagnosis

The electrical conductivity (EC) of milk is mainly a function of the electrolyte concentration in the milk and therefore raised in mastitis. The present investigation was aimed at elaborating, if possible, a diagnostic model for screening purposes based on EC determinations and consistent with the diagnostic procedures and interpretations commonly used in laboratory milk diagnosis in the Nordic countries (Klastrup 1975). According to this diagnosis (here called reference diagnosis) cell numbers above 300,000/ml (cell count or the corresponding CMT-score) in foremilk quarter samples during the main part of the lactation period and significantly above the lowest value on within-udder comparison during late lactation are considered indicative of mastitis and bacteriological examinations are made when called for.     

Electrophoretic behavior of the H+-ATPase proteolipid from bovine heart mitochondria

The proteolipid subunit of H⁺-ATPase was labeled by [¹⁴C]N,N-dicyclohexylcarbodiimide in bovine heart mitochondria. The radioactive labeling was followed using various systems of sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). When using discontinuous SDS-PAGE (Laemmli, U.K., 1970,Nature (London)227, 680–685) a monomeric (Mr 7600±1500) and a dimeric form (Mr 17,800±1200) of the proteolipid were detected, while only the monomeric form was found on urea (8 M) containing gels (SDS-PAGE according to Laemmli; or Swank, R. T., and Munkers, K. D., 1971,Anal. Biochem. 39, 462–477). When using SDS-PAGE with Na-P_i buffer (Weber, K., and Osborn, M., 1969,J. Biol. Chem. 244, 4406–4442), only a dimeric form of the proteolipid (Mr 15,000±1000) was detected. Experimental data indicate that the different patterns of proteolipid separation are related to the presence of the two distinct proteolipid conformations in the SDS solution.     

Lysis of autologous tumor cells by blood lymphocytes tested at the time of surgery

Summary Lymphocyte-mediated lysis of autologous tumor cells (autologous lymphocyte cytotoxocity ALC) was tested at the time of surgery in 108 patients (46 squamous cell carcinomas of the lung, 25 adenocarcinomas of the lung, 19 soft tissue sarcomas and 18 osteosarcomas). The clinical course of these patients in relation to the test results has been published previously. The group was evaluated again after an extended observation time, now with a mean of 80.2 months (range 36–108). The test was rarely positive in patients with metastasis (2 out of 28 experiments).There was a correlation between the ALC results and the postsurgical clinical course for patients without detectable metastasis in that (1) a negative test was invariably a bad prognostic sign, i.e., all 32 patients with negative ALC died within 3 years (mean survival time 16.1 months). (2) The remission and survival times were longer for the ALC positive patients (p<0.001). (3) All 37 individuals who are alive at present without recurrence belong to the reactive group.The ALC results correlated with the clinical course in 88% of patients. The correlation was highest for the groups of soft tissue sarcoma and adenocarcinoma of the lung. There was no correlation between killing of K562 cells and ALC, or between lymphoproliferative response to PHA and ALC reactivity.     

Cholinesterase activity in some species of theAllium genus

In partly purified protein complexes obtained from 22 species of theAllium genus and 6 cultivars ofAllium cepa the activity of cholinesterases was detected and measured using the method of Ellman et al. The degree of its inhibition with 10^-4 M neostigmine was also tested. It was found that the activity of cholinesterase differed in individual species up to two hundred times, while the differences in the inhibitory activity of 10^-4 M neostigmine occurred only in a few cases. Individual sections and cultivars could not be characterized on the basis of the differences in the activities of the cholinesterases. Of all the sections that ofPhyllodolon shows the highest average activity. In the case of the tested cultivars distinctly the lowest activity was observed in cv. Kastická. The values of the enzymatic activity measured by Ellman’s method in this plant material include the activity of specific and unspecific cholinesterases and the part uninhibitable by neostigmine.     

Developmental changes in gene expression during pollen differentiation and maturation inNicotiana tabacum L

Total and polysome-bound ribosomes and the uptake and incorporation of³H-uridine and¹⁴C-leucine were examined in dividing microspores and in pollen grains isolated from anthers of 6 different developmental stages. Direct evidence was obtained that the formation of cytoplasm of the vegetative cell following microspore division is related to a rapid activation of RNA and protein synthesis and of ribosomes in differentiating pollen. Total ribosomes associated with gametophytic programme rose about 10times and the process of differentiation was accompanied by a rapid increase in uptake capacity of pollen grains for both uridine and leucine. Pollen development after cytoplasm synthesis and starch deposition continued by pollen maturation, which was characterized by a decline in RNA synthesis, dissociation of polysomes and by a further rise of transport activity of pollen grain wall for exogenous substrates, indicating probable pollen adaptation for utilization of metabolites from the degenerating tapetal cytoplasm.