Growth Phase-Dependent Regulation of Vsr Endonuclease May Contribute to 5-Methylcytosine Mutational Hot Spots in Escherichia coli

Using rabbit polyclonal antibodies, we have shown that the Dcm cytosine methylase of Escherichia coli is maintained at a constant level during cell growth, while Vsr endonuclease levels are growth phase dependent. Decreased production of Vsr relative to Dcm during the log phase may contribute substantially to the mutability of 5-methylcytosine.     

Establishment of transformed root cultures of Perezia cuernavacana producing the sesquiterpene quinone perezone

Summary The sesquiterpene quinone currently known as perezone is abundantly produced by the roots of Perezia cuernavacana. This compound is of biotechnological interest since it may be used as a pigment and has several pharmacological properties. In this work we demonstrate that perezone is also produced in transformed root cultures of P. cuernavacana. Hairy roots were induced by inoculation of internodal segments of sterile plants of P. cuernavacana with Agrobacterium rhizogenes AR12 strain. The axenic liquid MS medium cultures of the hairy roots isolated from the internodes showed active growth in the absence of growth regulators. The transformed nature of the tissue was confirmed by genomic integration (PCR and slot blot hybridization) and expression (enzyme activity) of the marker gus-gene. The production of perezone by a transformed root culture was evidenced by IR spectroscopy. Our results offer an alternative for enhanced production of perezone and represent an advantage over its extraction from natural plant populations which present problems in their agronomic culture.     

Permineralized seed fern cupules from the Triassic of Antarctica: implications for cupule and carpel evolution

In this paper we describe the first anatomically preserved Mesozoic seed fern cupule–Petriellaea. The multiovulate cupules were produced singly at the end of a short dichotomizing axis. Cupules are bilateral with a dorsal groove and transverse narrow ventral opening. The vascular system of the cupule consists of a series of traces that extend up the dorsal surface of the cupule and down the ventral face. Ovules are orthotropus, sessile, and borne on the adaxial surface of the leaflike cupule either singly or in multiple rows. They are up to 1.5 mm long, triangular in transverse section, and characterized by a multilayered integument. Nucellus and integument are fused throughout their length, but no pollen chamber is present. In the chalaza is a small vascular disc of transfusion tracheids that represents the extent of the ovule vascular system. Ovules are interpreted as being fossilized at a prepollination stage, although a few possess some evidence of a cellularized megagametophyte. These permineralized cupules indicate that in at least one Mesozoic seed fern group, ovule enclosure resulted from the transverse folding (tip to petiole) of a megasporophyll bearing adaxial ovules. Cupule morphology and ovule enclosure in other Late Paleozoic and Mesozoic seed ferns is discussed.     

Exome Sequencing Identifies Rare Deleterious Mutations in DNA Repair Genes FANCC and BLM as Potential Breast Cancer Susceptibility Alleles

Despite intensive efforts using linkage and candidate gene approaches, the genetic etiology for the majority of families with a multi-generational breast cancer predisposition is unknown. In this study, we used whole-exome sequencing of thirty-three individuals from 15 breast cancer families to identify potential predisposing genes. Our analysis identified families with heterozygous, deleterious mutations in the DNA repair genes FANCC and BLM, which are responsible for the autosomal recessive disorders Fanconi Anemia and Bloom syndrome. In total, screening of all exons in these genes in 438 breast cancer families identified three with truncating mutations in FANCC and two with truncating mutations in BLM. Additional screening of FANCC mutation hotspot exons identified one pathogenic mutation among an additional 957 breast cancer families. Importantly, none of the deleterious mutations were identified among 464 healthy controls and are not reported in the 1,000 Genomes data. Given the rarity of Fanconi Anemia and Bloom syndrome disorders among Caucasian populations, the finding of multiple deleterious mutations in these critical DNA repair genes among high-risk breast cancer families is intriguing and suggestive of a predisposing role. Our data demonstrate the utility of intra-family exome-sequencing approaches to uncover cancer predisposition genes, but highlight the major challenge of definitively validating candidates where the incidence of sporadic disease is high, germline mutations are not fully penetrant, and individual predisposition genes may only account for a tiny proportion of breast cancer families.     

The use of synthetic genes for the expression of ciliate proteins in heterologous systems

The common fish parasite, Ichthyophthirius multifiliis, expresses abundant glycosylated phosphatidylinositol (GPI)-anchored membrane proteins known as immobilization antigens, or i-antigens. These proteins are targets of the host immune response, and have been identified as potential candidates for recombinant subunit vaccine development. Nevertheless, because Ichthyophthirius utilizes a non-standard genetic code, expression of the corresponding gene products, either as subunit antigens in conventional protein expression systems, or as vector-encoded antigens in the case of DNA vaccines, is far from straightforward. To overcome this problem, we utilized 'assembly polymerase chain reaction' to manufacture synthetic versions of two genes (designated IAG52A[G5/CC] and IAG52B[G5/CC]) encoding approximately 52/55 kDa i-antigens from parasite strain G5. This approach made it possible to eliminate unwanted stop codons and substitute the preferred codon usage of channel catfish for the native sequences of the genes. To determine whether the synthetic alleles could be expressed in cells that use the standard genetic code, we introduced IAG52A[G5/CC] into a variety of heterologous cell types and tested for expression either by immunofluorescence light microscopy or Western blotting. When cloned downstream of appropriate promoters, IAG52A[G5/CC] was expressed in Escherichia coli, mammalian COS-7 cells, and channel catfish where it elicited antigen-specific immune responses. Interestingly, the localization pattern of the corresponding gene product in COS-7 cells indicated that while the protein was correctly folded, it was not present on the cell membrane, suggesting that the signal peptides required for GPI-anchor addition differ in ciliate and mammalian systems. Construction of synthetic alleles should have practical utility in the development of vaccines against Ichthyophthirius, and at the same time, provide a general method for the expression of ciliate genes in heterologous systems.     

The role of high-dose-rate brachytherapy boost in breast-conserving therapy: Long-term results of the Hungarian National Institute of Oncology

AimTo report the long-term results of high-dose-rate (HDR) brachytherapy (BT) boost for breast cancer patients treated with conservative surgery and radiotherapy.Materials and methodsBetween 1995 and 2007, 100 early-stage breast cancer patients received an HDR BT boost after conservative surgery and whole breast irradiation. Ten patients (10%) received a single-fraction HDR boost of 8–10.35 Gy using rigid needles, while 90 (90%) were treated with a fractionated multi-catheter HDR BT boost. The latter consisted of 3 × 4 Gy (n = 19), 3 × 4.75 Gy (n = 70), and 2 × 6.4 Gy (n = 1). Breast cancer related events, cosmetic results and side effects were assessed.ResultsAt a median follow-up time of 94 months (range: 8–152) only 7 (7%) ipsilateral breast failures were observed for a 5- and 8-year actuarial rate of 4.5 and 7.0%, respectively. The 8-year disease-free, cancer-specific, and overall survival was 76.1, 82.8, and 80.4%, respectively. Cosmetic outcome was rated excellent in 17%, good in 39%, fair in 33%, and poor in 11%. Data on late radiation side effects were available for 91 patients (91%). Grade 3 fibrosis and grade 3 telangiectasia occurred in 6 (6.6%) and 2 (2.2%) patients, respectively. In univariate analysis only positive margin status had a significant negative effect on local control.ConclusionsHDR BT boost using multi-catheter implants produce excellent long-term local tumour control with acceptable cosmetic outcome and low rate of grade 3 late radiation side effects.     

Predictive systems ecology

Human societies, and their well-being, depend to a significant extent on the state of the ecosystems that surround them. These ecosystems are changing rapidly usually in response to anthropogenic changes in the environment. To determine the likely impact of environmental change on ecosystems and the best ways to manage them, it would be desirable to be able to predict their future states. We present a proposal to develop the paradigm of predictive systems ecology, explicitly to understand and predict the properties and behaviour of ecological systems. We discuss the necessary and desirable features of predictive systems ecology models. There are places where predictive systems ecology is already being practised and we summarize a range of terrestrial and marine examples. Significant challenges remain but we suggest that ecology would benefit both as a scientific discipline and increase its impact in society if it were to embrace the need to become more predictive.     

Diet ofColobus polykomos on Tiwai Island: Selection of food in relation to its seasonal abundance and nutritional quality

A group of Colobus polykomosat Tiwai, Sierra Leone, demonstrated seasonal flexibility in its diet, with seeds, young leaves, and mature leaves each dominating the diet at different times. Comparison of food consumption with phenological data indicates that seeds are eaten whenever available and are preferred to other foods, while young leaves are preferred to mature leaves. Colobus polykomosalso prefer liane to tree leaves, despite the relatively high quality of mature tree foliage at the Tiwai site. Analysis of protein, fiber, and energy values of foods selected and items available, but not eaten, suggests that preference is related to protein and energy maximization. Leguminous plants, especially Papilionaceae and Mimosaceae, are highlighted as important food sources for C. polykomos;seeds and leaves from these families have a high nitrogen content, and the protein content of leguminous seeds often equals or exceeds that found in leaves. It is predicted, therefore, that colobines living in habitats with a high density of legumes will feed heavily on seeds, subject to constraints such as seasonal availability. Where suitable leguminous species are less common, a mixture of fruits, seeds, and young or mature leaves or both is likely to be selected. The results of this and other recent studies of colobines do not support the notion that colobines are specialist folivores.