Evolution,developmental instability and the theory of acquisition

Despite major advances in the study of molecular and morphological evolution a substantial rift still exists between these two fields of endeavour. Phenotypic alteration through evolution results from a reallocation of resources which has as its origin the interplay between the production capability of the genes on the one side and the acquisitional need of the phenotype on the other. This process of allocation is coordinated through the environmental arena and is subject to mechanical, biological and economical constraints. Differences in the rates of morphological change at any level (molecular, cellular, organismal or population) depend on the level of environmental challenge, on the availability of variability and on the economics of supply and demand. Short run changes in response to severe environmental stress will be sudden and energetically expensive and will rely on stress-induced unmasking of genetic variability and loss of canalization. Long run changes will be gradual, energetically less costly and less dependent on genetic correlations.     

Allometric relations of teeth and jaws in man

Static adult intraspecific allometry of jaws and teeth was investigated in a sample of 100 Negro crania. The relations between tooth area, postcanine surface, incisor surface, and four viscerocranial measures were examined separately for males and females. Our results indicate a marked lack of morphological integration between P-sets within the orofacial subregion and a similar lack of correspondence between jaw size and tooth size. Allometric analyses indicate that mandibular length scales negatively allometric to maxilloalveolar length and to bigonial width, that canine base area scales positively to upper and lower jaw length, and that all the other teeth scale negatively to jaw length. The postcanine surface area was found to be negatively allometric to the canine base area, which in turn scaled isometrically to incisor surface. Hence, any lengthening of the mandible will tend to be associated with a relative shortening of the maxilla, with relatively larger canines and a relative reduction of the cheek teeth.     

A combined genetic and physical map of the Streptomyces coelicolor A3(2) chromosome.

The restriction enzymes AseI (ATTAAT), DraI (TTTAAA), and SspI (AATATT) cut the Streptomyces coelicolor A3(2) chromosome into 17, 8, and 25 fragments separable by pulsed-field gel electrophoresis (PFGE). The sums of their lengths indicated that the chromosome consists of about 8 Mb of DNA, some 75% more than that of Escherichia coli K-12. A physical map of the chromosome was constructed for AseI and DraI, using single and double digests, linking clones, cross-hybridization of restriction fragments, and locations of genetically mapped genes, insertion sequences, prophages, and the integrated SCP1 and SLP1 plasmids on the physical map. The physical map was aligned with the previously established genetic map, revealing that the two long opposite quadrants of the genetic map that are almost devoid of markers (the silent regions at 3 o'clock and 9 o'clock) are indeed physically long rather than being hot spots for genetic exchange. They must therefore contain long stretches of DNA different in function from the remainder of the genome. Consistent with this conclusion are the locations of significant deletions in both of the silent regions. Of these, a 40-kb deletion in the 9 o'clock region accompanied or followed integration of the SCP1 linear plasmid to produce the NF fertility state. PFGE analysis of Streptomyces lividans 66, a close relative of S. coelicolor A3(2), was hampered by the previously described susceptibility of its DNA to degradation during electrophoresis. However, ZX7, a mutant derivative of S. lividans lacking the DNA modification responsible for this degradation, yielded good PFGE preparations. Not more than 7 of the 17 S. coelicolor AseI fragments could be shared by the S. lividans strain.     

Cloning of a chloramphenicol acetyltransferase gene of Streptomyces acrimycini and its expression in Streptomyces and Escherichia coli

A gene (cat) for chloramphenicol (Cm) acetyltransferase (CAT) was cloned from Streptomyces acrimycini into S. lividans 66 on the plasmid vector pIJ61. The cat gene was localized on a 1.7-kb BclI fragment, which probably also carries the cat promoter. This DNA fragment conferred Cm resistance, through CAT activity, on S. lividans, S. coelicolor and S. parvulus, but not on Escherichia coli when inserted in the BamHI site of the tetracycline-resistance(TcR) gene of pBR322. However, when inserted in a particular orientation in this site, spontaneous deletions of 0.7 kb led to CAT activity and Cm resistance. DNA homologous to the 1.7-kb BclI cat fragment was found in most, but not all, of a series of other streptomycetes that have CAT activity. The cat provides a potentially useful screening marker for Streptomyces cloning vectors.     

Performance of Biomarker-Based Subgroup Selection Rules in Adaptive Enrichment Designs

In the planning stage of a clinical trial investigating a potentially targeted therapy, there is commonly a high degree of uncertainty whether the treatment is more efficient (or efficient only) in a subgroup compared to the whole population. Recently developed adaptive designs enable to allow for an efficacy assessment both for the whole population and a subgroup and to select the target population mid-course based on interim results (see, e.g., Wang et al., Pharm Stat 6:227–244, 2007, Brannath et al., Stat Med 28:1445–1463, 2009, Wang et al., Biom J 51:358–374, 2009, Jenkins et al., Pharm Stat 10:347–356, 2011, Friede et al., Stat Med 31:4309–4120, 2012). Frequently, predictive biomarkers are used in these trials for identifying patients more likely to benefit from a drug. We consider the situation that the selection of the patient population is based on a biomarker and where the diagnostics that evaluates the biomarker may be perfect, i.e., with 100 % sensitivity and specificity, or not. The performance of the applied subset selection rule is crucial for the overall characteristics of the design. In the setting of an adaptive enrichment design, we evaluate the properties of subgroup selection rules in terms of type I error rate and power by taking into account decision rules with a fixed ad hoc threshold and optimal decision rules developed for the situation of uncertain assumptions. In a simulation study, we demonstrate that designs with optimal decision rules are under certain assumptions more powerful as compared to those with ad hoc decision rules. Throughout the results, a strong impact of sensitivity and specificity of the biomarker on both type I error rate and power is observed.     

Cloning and amplified expression in Streptomyces lividans of a gene encoding extracellular beta-lactamase from Streptomyces albus G

A 4.9-kb DNA fragment containing the bla gene for the extracellular beta-lactamase (BLA) of Streptomyces albus G was cloned in Streptomyces lividans using the conjugative, low-copy-number plasmid pIJ61 as vector. No expression of bla was observed when this DNA fragment was introduced into Escherichia coli HB101 on a plasmid vector. A 1.5-kb PstI-SstI fragment containing the bla gene was cloned in S. lividans on the nonconjugative, high-copy-number plasmid pIJ702. A tenfold higher yield of BLA was obtained from S. lividans carrying this plasmid than from S. albus G grown under optimal production conditions. The BLA from the clone reacts with beta-iodopenicillanate according to a branched pathway which is characteristic of the original S. albus G BLA enzyme.     

Factors affecting the isolation of CCC DNA from Streptomyces lividans and Escherichia coli

Based on the results of a systematic study of factors affecting plasmid yield and purity, a procedure suitable for the rapid screening for and isolation of covalently closed circular DNA from Streptomyces lividans and Escherichia coli was developed. The method consists of lysis of lysozyme-treated bacteria combined with alkaline denaturation of DNA at high temperature. Renaturation of CCC DNA and precipitation of single-stranded DNA together with protein is achieved by the addition of a minimal amount of phenol/chloroform. The screening procedure uses only a single tube and the samples can be analyzed by agarose gel electrophoresis about 30 min after lysis. Removal of phenol and further purification of the plasmid preparation is achieved by consecutive precipitations with isopropanol and spermine, followed by extraction with ethanol, producing samples suitable for restriction endonuclease digestion, ligation, and transformation of S. lividans protoplasts or competent E. coli cells in about 2 h. All steps of the procedure are explained in detail with information about the effects of changing parameters. This should help the experimenter to obtain reproducible results and may be useful if the method has to be adapted to new strains or plasmids.     

Activity of a Streptomyces transcriptional terminator in Escherichia coli.

A 205bp DNA fragment from the Streptomyces multi-copy plasmid pIJ101 has in vivo terminator activity both in Streptomyces lividans and in Escherichia coli. Termination of RNA synthesis, detected by high-resolution S1 nuclease mapping, occurs at precisely the same nucleotides in both organisms. This suggests that the E. coli RNA polymerase recognizes the same sequence elements and chooses the point(s) of termination in the same way as the corresponding S. lividans enzyme.     

Factors influencing the Flavour of Cider: the Effect of Fermentation Treatments on Fusel Oil Production

S ummary . The flavour of cider is due to both nonvolatile and volatile components. Fermentation treatments cause changes in acidity and influence the formation of higher alcohols or fusel oil. Only the latter are discussed in detail. Preliminary results show that temperature and yeast strain are important factors in their production.     

Experiences and perceptions of oral health and oral health care among a sample of older New Zealanders

doi: 10.1111/j.1741‐2358.2010.00402.x Experiences and perceptions of oral health and oral health care among a sample of older New Zealanders Background: Most research on older people’s oral health has been quantitative. A need for more in‐depth understanding of the oral health of that age group has pointed to a need for more qualitative investigations. Objective: To explore experiences and perceptions of oral health and oral health care among an ethnically‐mixed sample of older New Zealanders. Methods: In‐depth interviews were conducted with 24 older people in two communities in New Zealand’s South Island. Thematic analysis of transcribed data was undertaken. Results: Three main themes that emerged were: (1) the processes of negotiating a tension between cost and convenience of access; (2) the experiential constraining of oral health maintenance; and (3) trusting in dental professionals. These serve to organise processes such as normalising, justifying and social comparisons that create an equilibrium or tolerance and acceptance of what might otherwise be considered to be relatively poor oral health. Conclusions: We identified a number of shared experiences which affect older people’s ability to maintain their oral health in the face of material and social barriers to oral health care. Because expectations were generally lower, there was greater concordance between experience and expectation, and people tended to be fairly satisfied with their oral health and the care they had received.