The "suppressive side" of yeast mitotic cyclins

Comment on: Signon L. Cell Cycle 2011; 10:1655-68.     

The C : N : P stoichiometry of autotrophs – theory and observations

Evolution has set biochemical constraints on the chemical composition of living organisms. These constraints seem to lead to increases in N : C and P : C ratios with increasing relative growth rate for all types of organisms. The N : P ratio also seems to decrease with relative growth rate for heterotrophs whereas autotrophs may show a more complex behaviour. Here I will show that, from biochemical considerations, N : C should increase linearly and P : C quadratically with relative growth rate in autotrophs with the consequence that N : P increases at low relative growth rates, passes a maximum and then decreases at high relative growth rates. These predictions are verified against observations for a freshwater alga (Selenastrum minutum) and a tree seedling (Betula pendula). Changes in temperature, light or other factors that affect the growth rate of autotrophs interact with nutrient supply in such a way that there are no simple rules for as to how N : P will change.     

The Leopard's Tale: Revealing the Mysteries of Çatalhöyük

The Leopard's Tale: Revealing the Mysteries of Çatalhöyük . Ian Hodder. New York: Thames and Hudson, 2006. 288 pp.     

The EN-TEx resource of multi-tissue personal epigenomes & variant-impact models

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Yânomamö Interactive: The Ax Fight on CD-ROM

Yânomamö Interactive: The Ax Fight on CD-ROM. Peter Biella. Napoleon A. Chagnon. and Gary Seaman. Fort Worth, TX: Harcourt Brace College Publishers, 1997.     

The “<Emphasis Type="Italic">Tetrahymena pyriformis</Emphasis>” complex of cryptic species

Cryptic species are common among protists and have long been known in ciliates. The ciliate genus Tetrahymena contains a large group of morphologically indistinguishable species referred to as the ‘T. pyriformis’ complex. These species include those reproductively isolated by mating type as well as asexual species characterized by the absence of the germinal micronucleus. This paper examines the molecular diversity of the species and describes the biogeography of ‘T. pyriformis’ species. Most species are globally distributed, though the best studied species, T. thermophila, is confined to North America and gives evidence of population structure in local populations. Selfers and asexual species are common and arise from sexual species, a possible exploitation of nuclear dimorphism. It is argued that the cryptic species likely have different ecological roles and that the biodiversity of Tetrahymena in particular, and ciliates in general, is underestimated. Special Issue: Protist diversity and geographic distribution. Guest editor: W. Foissner.     

The Hsa-miR-27a rs895819 (A > G) polymorphism and cancer susceptibility

Published data on the association between the rs895819 (A > G) polymorphism in the terminal loop of pre-miR-27a and cancer risk is inconclusive. Therefore, we conducted a meta-analysis to estimate the association between this polymorphism and cancer. The PubMed, Web of science, and Embase databases were searched for articles on the hsa-miR-27a rs895819 polymorphism and cancer risk published up to November 24, 2012. The genotype data obtained in the searches were pooled in our meta-analysis, and pooled odds ratio (OR) with 95% confidence interval (CI) was used to assess the association. Seven studies with a total of 3849 cases and 4781 controls were eligible for analysis. Overall, we found no significant associations between the hsa-miR-27a rs895819 (A > G) polymorphism and cancer susceptibility (homozygote model: OR = 0.88, 95% CI: 0.68–1.14; heterozygote model: OR = 0.96, 95% CI: 0.79–1.17; dominant model: OR = 0.94, 95% CI: 0.79–1.12; recessive model: OR = 0.88, 95% CI: 0.69–1.12). In the subgroup analysis by ethnicity, we found that the rs895819 AG genotype was associated with a decreased risk of cancer in white individuals (dominant model: OR = 0.85, 95% CI: 0.76–0.94; heterozygote model: OR = 0.84, 95% CI: 0.75–0.94). This meta-analysis indicated that the hsa-miR-27a rs895819 polymorphism did not correlate with overall cancer risk in the general population. However, the rs895819 AG genotype may protect against the development of cancer in white individuals. Larger, better studies of homogeneous cancer patients are needed to further assess the correlation between this polymorphism and cancer risk.     

The Composition of fatty acids and aldehydes of the marine bryozoans <Emphasis Type="Italic">Berenicea meandrina</Emphasis> and <Emphasis Type="Italic">Dendrobeania flustroides</Emphasis> (Bryozoa: Gymnolaemata)

This study examines the composition of lipids, fatty acids, and fatty aldehydes in two marine bryozoan species, Berenicea meandrina and Dendrobeania flustroides, from the Sea of Okhotsk. The share of neutral lipids was up to 57.3% in D. flustroides and 54.9% in B. meandrina; the share of polar lipids was 33.2 and 40.4%, respectively. In all, 57 fatty acids (FA) and 9 aldehydes were identified in total lipids. The main FAs were 16:0, 18:0, 22:6n-3, and 20:5n-3. The content of branched saturated FA in bryozoans was on the average 6.4%. Three isomers of 16:1 (n-9, n-7, and n-5), five isomers of 18:1 (n-13, n-11, n-9, n-7, and n-5), four isomers of 20:1 (n-13, n-11, n-9, and n-7), as well as 22:1n-9 and 22:1n-13 were found; the presence of 7-methyl-6-hexadienoic acid (on the average, 3.0% of total FAs) was demonstrated. Non-methylene-inter-rupted FAs contributed 8.9 and 1.6% of the total FAs in D. flustroides and B. meandrina, respectively, and were identified as 20:2(5,11), 20:2(7,13), 20:3(5,11,14), 22:2(7,13), and 22:2(7,15). In B. meandrina, minor amounts of 24:0, 24:1, 25:0, 26:0, 24:4n-3, 26:3(5,9,19), and 28:3(5,9,19) were found, suggesting sponge biofouling on some bryozoan colonies. Aldehydes (branched saturated and unsaturated C_16–19 homologues) did not exceed 10.3 and 1.9% of the total FAs in D. flustroides and B. meandrina, respectively. The presence of the FA markers that are characteristic of microalgae, protozoans, and detritus in bryozoan lipids agrees well with data on polytrophic feeding of these bryozoans.     

The older plant gets the sun: Age‐related changes in Miscanthus × giganteus phenology

Age‐related changes are usually overlooked in perennial grass research; when they are considered it is usually as a change in plant size (e.g., biomass). Whether other physiological or developmental aspects change as stands age, and how those aspects may impact long‐term stand dynamics, remains unclear. Conventional experimental designs study a single stand over multiple growing seasons and thereby confound age‐related changes with growing season conditions. Here we used a staggered‐start experimental design with three repeated planting years over two growing seasons to isolate growing season effects. We studied changes in Miscanthus × giganteus phenology during its yield‐building stage (first 3 years) and estimated age, growing season and nitrogen (N) effects on development using nonlinear regression parameters. Stand age clearly changed plant growth; faster developmental rates were usually seen in 1‐year‐old stands (young), but because 2‐ and 3‐year‐old stands (mature) emerged 3 months earlier than newly planted stands they produced 30% more stems with 30%–60% more leaves. Nitrogen fertilization modulated some age‐related phenological changes. Fertilized 2‐year‐old stands reached similar stem densities as unfertilized 3‐year‐old stands and had fewer number of senesced leaves like 1‐year‐old stands. In addition, N fertilization had no effect on young M. × giganteus, but extended mature stands’ growing season more than 2 weeks by hastening emergence and delaying senescence. It also delayed flowering regardless of stand age. Our results suggest that, along with changes in size, M. × giganteus stands showed shifts in developmental strategies: young stands emerged later and developed faster, while mature stands grew for longer but more slowly. In temperate regions, where hard frost events are likely to interrupt development in late autumn, rapid early development is critical to plant survival. Nonlinear regression parameter differences proved effective in identifying phenological shifts.     

The respiratory supercomplex from C. glutamicum

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The role of a cytosolic superoxide dismutase in barley–pathogen interactions

Reactive oxygen species (ROS), including superoxide ( / ) and hydrogen peroxide (H₂O₂), are differentially produced during resistance responses to biotrophic pathogens and during susceptible responses to necrotrophic and hemi‐biotrophic pathogens. Superoxide dismutase (SOD) is responsible for the catalysis of the dismutation of / to H₂O₂, regulating the redox status of plant cells. Increased SOD activity has been correlated previously with resistance in barley to the hemi‐biotrophic pathogen Pyrenophora teres f. teres (Ptt, the causal agent of the net form of net blotch disease), but the role of individual isoforms of SOD has not been studied. A cytosolic CuZnSOD, HvCSD1, was isolated from barley and characterized as being expressed in tissue from different developmental stages. HvCSD1 was up‐regulated during the interaction with Ptt and to a greater extent during the resistance response. Net blotch disease symptoms and fungal growth were not as pronounced in transgenic HvCSD1 knockdown lines in a susceptible background (cv. Golden Promise), when compared with wild‐type plants, suggesting that cytosolic / contributes to the signalling required to induce a defence response to Ptt. There was no effect of HvCSD1 knockdown on infection by the hemi‐biotrophic rice blast pathogen Magnaporthe oryzae or the biotrophic powdery mildew pathogen Blumeria graminis f. sp. hordei, but HvCSD1 also played a role in the regulation of lesion development by methyl viologen. Together, these results suggest that HvCSD1 could be important in the maintenance of the cytosolic redox status and in the differential regulation of responses to pathogens with different lifestyles.     

The extracellular β‐1,3‐endoglucanase EngA is involved in autolysis of Aspergillus nidulans

Aims: To elucidate the roles of the β‐1,3‐endoglucanase EngA in autolysis of the filamentous fungus Aspergillus nidulans and to identify the common regulatory elements of autolytic hydrolases. Methods and Results: A β‐1,3‐endoglucanase was purified from carbon‐starving cultures of A. nidulans. This enzyme is found to be encoded by the engA gene (locus ID: AN0472.3). Functional and gene‐expression studies demonstrated that EngA is involved in the autolytic cell wall degradation resulting from carbon starvation of the fungus. Moreover, regulation of engA is found to be dependent on the FluG/BrlA asexual sporulation signalling pathway in submerged culture. The deletion of either engA or chiB (encoding an endochitinase) caused highly reduced production of hydrolases in general. Conclusions: The β‐1,3‐endoglucanase EngA plays a pivotal role in fungal autolysis, and activities of both EngA and ChiB are necessary to orchestrate the expression of autolytic hydrolases. The production of cell wall–degrading enzymes was coordinately controlled in a highly sophisticated and complex manner. Significance and Impact of the Study: No information was available on the autolytic glucanase(s) of the euascomycete A. nidulans. This study demonstrates that EngA is a key element in fungal autolysis, and normal activities of both EngA and ChiB are crucial for balanced production of hydrolases.     

The Flexible Feminine in Vietnam: ‘Ordinary’ Goddesses and Extraordinary Ethnography

Book reviewed in this article: Philip Taylor . Goddess on the Rise: Pilgrimage and Popular Religion in Vietnam     

The infrageneric nomenclature of <Emphasis Type="Italic">Tulipa</Emphasis> (Liliaceae)

Zonneveld (Pl Syst Evol 281:217–245, 2009) proposed an infrageneric classification of Tulipa (Liliaceae) based on the nuclear content determined by flow cytometry and available morphological data. The nomenclatural consequences of this are discussed here, involving the typification of generic and infrageneric names. Additional notes on some species are given. Four subgenera are distinguished, of which two are new; ten sections are proposed, four new; three new combinations are made, and seven lectotypes are designated. Tulipa praecox Ten. is a later homonym of T. praecox Cav. (Descripcíon de las plantas. 2: 448, 625, 1803); its correct name is Tulipa agenensis DC. Tulipa lemmersii Zonn., A. Peterse, J. de Groot is validated here by giving the type citation.     

The Mössbauer and magnetic properties of ferritin cores

Background: Mössbauer and magnetization measurements, singly or in combination, extract detailed information on the microscopic or internal magnetism of iron-based materials and their macroscopic or bulk magnetization. The combination of the two techniques affords a powerful investigatory probe into spin relaxation processes of nanosize magnetic systems. The ferritin core constitutes a paradigm of such nano-magnetic system where Mössbauer and magnetization studies have been broadly combined in order to elucidate its composition, the initial steps of iron nucleation and biomineralization, particle growth and core-size distribution. In vivo produced and in vitro reconstituted wild-type and variant ferritins have been extensively studied in order to elucidate structure/function correlations and ferritin’s role in iron overloading or neurodegenerative disorders.Scope of Review: Studies on the initial stages of iron biomineralization, biomimetic synthetic analogues and ferrous ion retention within the ferritin core are presented. The dynamical magnetic properties of ferritin by Mössbauer and magnetization measurements are critically reviewed. The focus is on experiments that reveal the internal magnetic structure of the ferritin core. Novel magnetic measurements on individual ferritin molecules via AFM and nanoSQUID investigations are also mentioned. Major Conclusions: A complex two-phase spin system is revealed due to finite-size effects and non-compensated spins at the surface of the anti-ferromagnetic ferritin core. Below the blocking temperature surface spins participate in relaxation processes much faster than those associated with collective magnetic excitations of interior spins. General Significance: The studies reviewed contribute uniquely to the elucidation of the spin-structure and spin-dynamics of anti-ferromagnetic nanolattices and their possible applications to nano/bio-technology.     

The effect of low temperature on fatty acid composition and tocopherols of the red microalga, <Emphasis Type="Italic">Porphyridium cruentum</Emphasis>

Porphyridium cruentum was grown in 10 L batch culture at 18°C, pH 8.0 and 28‰ salinity. The cells were harvested in the stationary phase and the fatty acid composition analysed by GC and tocopherol content by HPLC. A total of 14 fatty acids were identified including saturated fatty acids (13:0, 14:0, 14:0 iso, 15:0, 16:0, 16:0iso) and monounsaturated fatty acids (MUFAs; 16:1(n-7), 18:1(n-7), 18:1(n-9). Polyunsaturated fatty acids (PUFAs) were the predominant fatty acids detected, reaching 43.7% of total fatty acids in the stationary phase of culture. Among the PUFAs, eicosapentaenoic acid (EPA, 20:5(n-3)) was dominant (25.4%), followed by 12.8% arachidonic acid (AA, 20:4(n-6)). α-Tocopherol and γ-tocopherol contents were 55.2 μg g⁻¹ dry weight and 51.3 μg g⁻¹ dry weight respectively.