A small cosmid for efficient cloning of large DNA fragments

The production and use of the 6 kb cosmid pHC79, a derivative of pBR322, is described. It can be used for cloning of fragments cleaved by EcoRI, ClaI, BamHI (also BglII, BclI, Sau3A and MboI), SalI (also XhoI and AvaI), EcaI and PstI. Hybrid cosmids containing inserts in the size range of 40 kb are packaged in vitro and transduced with an efficiency of 5 X 10(4) - 5 X 10(5) clones/microgram of insert DNA. Prefractionation of the DNA fragments to be cloned into 40 kb sized fragments ensures the cloning of contiguous stretches of DNA. Proteins produced in vitro by the cosmid pHC79 are identical to the ones produced by its pBR322 parent.

Oestrogen use and survival in endometrial cancer

Of 860 women with endometrial cancer registered in a regional cancer treatment centre, 259 (30%) gave a history of oestrogen use for 6 months or more at some time before diagnosis, and 568 (66%) were non-users. OEstrogen use was associated with younger age, earlier stage, lower grade of tumour, less common myometrial invasion, and preferred treatment including radiation and hysterectomy. The 5-year survival of oestrogen users was 92 +/- 2% compared with 68 +/- 2% for non-users. Further analysis controlling for differences in the distribution of the variables associated with survival showed that for women who have endometrial cancer, the risk of any death for non-users is approximately 2-7 times greater than for oestrogen users, and the risk of death from endometrial cancer is 5.4 times greater for non-users. A history of oestrogen use is not associated with superior survival of women who have poorly differentiated tumours or myometrial invasion.

Bronchoalveolar lavage for the preparation of free lung cells: technique and complications

Bronchoalveolar lavage at fibreoptic bronchoscopy enables the peripheral bronchoalveolar free cell population, which consists mainly of lymphocytes and macrophages, to be sampled. The yield is sufficient for detailed morphological and functional investigation of these cells, which can be separated by exploiting the glass-adherent or phagocytic properties of macrophages. Such studies are of particular interest in patients with recurrent chest infections, to detect abnormalities of local cellular immunity; in pulmonary fibrosis to assess activity of the disease and effect of treatment by observing morphology and testing function of free lung cells; and in bronchial carcinoma to investigate local immune responses to the tumour. The procedure is held to be ethical in these circumstances. The lavage consists of irrigation of a segmental bronchus through the fibreoptic bronchoscope with up to 500 ml pH-corrected normal saline solution. It is contraindicated in those with respiratory or cardiac risk, but is tolerated well by most patients. Complications include acute respiratory distress, vasovagal syncope and fever with pulmonary infiltrates. Lavage is associated with a mean fall of PaO2 of 3.0 kPa (22.7 mmHg) and routine oxygen supplementation is recommended.

Possible priming effect of luteinizing hormone releasing hormone on the anterior pituitary gland in the Japanese quail and the stimulation of secretion of follicle-stimulating hormone

After the i.m. injection of 10 micrograms synthetic LH releasing hormone (LH-RH) into Japanese quail the levels of LH and FSH in plasma rose significantly within 2 min. The increased level of LH declined rapidly but that of FSH was maintained for the duration of the experiment. To determine whether the anterior pituitary gland is primed by LH-RH a double injection schedule was adopted. It would appear that, while endogenous LH-RH may prime the avian pituitary gland slightly, synthetic LH-RH is ineffective.

Deletions, insertions and rearrangements affecting rpoB gene expression

Through cloning and deletion experiments on ColEl hybrids the rpoB gene (Rifr) was located on a physical restriction map; RNA polymerase binding studies showed no binding site within the structural gene. The genetic data and RNA polymerase binding studies lead to the conclusion that rp/L and rpoB are dependent upon a common promoter.

Expression of Escherichia coli ribosomal protein and RNA polymerase genes cloned on plasmids

Fragments of lambda drifd 18 DNA with different end-points within the set of structural genes of ribosomal proteins L11 (RPLK), Li (rplA), L10 (rplJ) and L12 (rplL) as well as the beta (rpoB) ANd beta' (rpoC) subunits of RNA polymerase have been cloned on plasmids. These plasmids were transformed in host cells which were mutant for each of the genes, enabling expression of both wild-type (plasmid-borne) and mutant (chromosomal) genes to be differentiated. On the basis of these results we propose the following genetic structure for the region: rplK and rplA are in one operon; rplL, rpoB and rpoC are in a second. Our data suggest the possibility that rplJ is by itself in an operon situated between the other two.

Cell-free synthesis of proteins coding for mobilisation functions of ColE1 and transposition functions of Tn3

A hybrid plasmid, pJC74, carrying the large (3.35 Md) EcoRI-PstI fragment of ColE1, the 1.3 and 1.8 Md PstI fragments of plasmid R1 drd19 (containing a part of Tn3 and known to specify transpostion functions), and a part of gamma bacteriophage DNA carrying the fused cohesive ends of gamma (cos) was constructed. Supercoiled DNA of pJC74 and a series of deletions (series pJC75) were used in a cell-free coupled transcription-translation system. Analysis of the proteins produced allowed the identification of a 28 to 30 kd protein and/or a 3 kd protein responsible for mobilisation of the plasmids in sex-factor-promoted conjugation. Furthermore, three protein bands of 12, 12.5 and 13 kd were correlated with the presence of a portion of the Tn3 transposon previously shown to code for transposition functions which can complement in trans. These latter and the 30 kd beta-lactamase were the only proteins identified as Tn3-specific by comparison of ColE1 with RSF2124.

Altered DNA-protein relaxation complex in a replication mutant of plasmid ColE1

Approximately 200,000 clones of Escherichia coli carrying mutagen-treated colicinogenic plasmid E1 (ColE1) were examined for irreversible loss of the plasmid at 43 degrees. Thirty of these clones that appeared to be most defective in plasmid DNA replication at the non-permissive temperature were selected for the study of: (a) the kinetics of plasmid and chromosomal DNA replication during a temperature shift in either the presence or absence of chloramphenicol; (b) the temperature stability of the plasmid DNA-protein relaxation complex; and (c) the temperature effect on F-promoted conjugal transfer. Two mutant plasmids, pJC307 and pJC301, showed defects in their relaxation complex. The relaxation complex of pJC307 exhibited an altered temperature stability in vitro. Reversion to temperature resistant replication resulted in four out of five cases in a concomitant change in the temperature stability of the relaxation complex. Conjugal mobility of this mutant was not markedly reduced at the permissive or non-permissive temperature. Plasmid pJC301 could not be isolated in the form of a relaxation complex and it was very poorly mobilized in an F'-promoted conjugation. These results indicate that the ColE1 plasmid codes for at least one of the proteins of the relaxation complex and that the relaxation complex is involved in ColE1 DNA replication. In addition, the properties of the mutant plasmid pJC301 are consistent with a role for the complex in the mobilization of ColE1 during conjugation.

Plasmids useable as gene-cloning vectors in an in vitro packaging by coliphage lambda: "cosmids"

A plasmid which contains a cos site of lambda and can be packaged into lambda bacteriophage particles is termed a "cosmid". Such plasmids can be used as gene cloning vectors in conjunction with an in vitro packaging system. The properties of a new series of cosmids based on the ColE1 replicon are described, including small temperature-sensitive plasmids which have lost mobilisation functions and carry no IS sequences. Amongst these plasmids are vectors for XmaI, BglII, BamHI, HindIII, PstI, KpnI, SalI and EcoRI. It is demonstrated that by using cosmids in particular size ranges these plasmids provide a high efficiency cloning system which yields essentially only hybrid clones without resort to a second selection or screening step, and without prior modification (e.g. phosphatase) treatment of the DNA. Attempts were made to optimise the cloning properties of the cosmid system. An Escherichia coli "gene bank" was obtained with an efficiency of 5 . 10(5) clones per microgram of E. coli DNA, and in which any particular unselected marker may be found in about one out of every 400 clones. It was demonstrated that deletion of mobilisation functions leads to loss of ability to form relaxation-complex without affecting copy number or segregation properties of the temperature-sensitive derivatives. The vectors are amplifiable in chloramphenicol to make up about 50% of the total cellular DNA.

Cosmids: a type of plasmid gene-cloning vector that is packageable in vitro in bacteriophage lambda heads

Evidence is presented that ColE1 hybrid plasmids carrying the cohesive-end site (cos) of lambda can be used as gene cloning vectors in conjunction with the lambda in vitro packaging system of Hohn and Murray [(1977) Proc. Natl. Acad. Sci. USA 74, 3259--3263]. Due to the requirement for a large DNA molecule for efficient packaging, there is a direct selection for hybrids carrying large sections of foreign DNA. The small vector plasmids do not contribute a large background in the transduced population, which is therefore markedly enriched for large hybrid plasmids (over 90%). The efficiency of the in vitro packaging system is on the order of 10(5) hybrid clones per microgram of foreign DNA for hybrids in the 20--30 million dalton range.

The expression of tetracycline resistance after insertion of foreign DNA fragments between the EcoRI and HindIII sites of the plasmid cloning vector pBR 322

In vitro recombination techniques were used to construct hybrid plasmids between pBR 322 and different DNA fragments derived from pML 21 and the E. coli chromosome. Some of the resulting hybrid plasmids express the tetracycline resistance gene of pBR 322, depending on the DNA fragment which has been ligated into the HindIII-site of pBR 322. From these studies we could conclude the direction of transcription of the kanamycin resistance gene in plasmid pML 21 with respect to the SalI, SmaI, HincII, KpnI, EcoRI and HindIII restriction sites. The replacement of the small HindIII-EcoRI-fragment in pBR 322 by other DNA fragments from the E. coli chromosome and selection for tcr-phenotypes showed that this system may be very useful for screening and analysis of promotor-containing DNA fragments.

A ribosomal RNA gene, rrnC, of Escherichia coli, mapped by specialized transducing lambdadilv and lambda drbs phages

Specialized transducing phages carrying segments of the Escherichia coli chromosome from the rbs-ilv region including rrn genes have been isolated. These phages carry rrn transcription units coding for 16S and 23S rRNA with the direction of transcription clockwise towards the ilv operon. While one of the phages (lambdad279rbs) appears to carry the genuine rrn gene, denoted rrnC, located between rbs and ilv at 82 min on the E. coli chromosome another one isolated as an ilv transducing phage, lambda5ilv, carries a hybrid rrn gene, denoted rrnX, which has originated from a recombinational cross-over between the rrnC and one of the other rrn genes.

Diabetes mellitus in an urbanized, isolated Polynesian population. The Funafuti survey

An epidemiologic study of diabetes in the urbanized Polynesian population of Funafuti has established a prevalence of 8 per cent in subjects aged 10 years and over. Of these, 0.9 per cent were known diabetics, and the remainder were diagnosed on the basis of a plasma glucose level of at least 160 mg./100 ml. two hours after a 75 gm. glucose load. A further 5.9 per cent had borderline diabetes as judged by a two-hour postload plasma glucose of 140-159 mg./100 ml. In those aged 20 years and over, the prevalence of diabetes was 10.1 per cent, similar to that reported in other acculturated Polynesian groups. The prevalence of both borderline diabetes and frank diabetes was twice as high in the females as in males. This difference appeared to be related to the greater degree of obesity in the females, but the prevalence was not related to parity. The increase in frequency of diabetes among these islanders coincides with a change of traditional island life style to that of urbanized Western populations. The results suggest that there may be 10 times the actual number of known diabetics in some Pacific populations.

On the structure of the deo operon of Escherichia coli

A characterization of a specialized transducing lambda phage for the deo operon (lambdaddeo), and some composite colE1-deo plasmids is given in this paper. This includes localization of the RSmaI, RHind/III, RBamI, and REcoRI sensitive sites. The deo genes have been localized by construction of composite colE1-deo plasmids. Using the DNA fragments, obtained by digestion with REcoRI and RHindIII, respectively, as templates in an in vitro protein synthesizing system, it has been possible to give the direction of transcription and the exact location of the deo genes, relative to the endonuclease sites. Furthermore, the cytO,P and deoO,P regions have been mapped relative to the structural genes. Supercoiled co1E1-deo DNA has been used as template in the in vitro system; this DNA gives essentially the same results as the endonuclease-fragmented DNA. The use of the different types of templates is discussed.

A single radial haemolysis technique for the measurement of antibody to Mycoplasma bovis in bovine sera

A single radial haemolysis in gel technique is described for assaying antibody to Mycoplasma bovis (M agalactiae subsp bovis) in bovine sera. The test, which should be particularly useful for screening large numbers of serum samples, is sensitive, simple to perform and highly reproducible.