Antipredatory function of head shape for vipers and their mimics

Most research into the adaptive significance of warning signals has focused on the colouration and patterns of prey animals. However, behaviour, odour and body shape can also have signal functions and thereby reduce predators' willingness to attack defended prey. European vipers all have a distinctive triangular head shape; and they are all venomous. Several non-venomous snakes, including the subfamily Natricinae, commonly flatten their heads (also known as head triangulation) when disturbed. The adaptive significance of this potential behavioural mimicry has never been investigated.We experimentally tested if the triangular head shape typical of vipers offers protection against predation. We compared the predation pressure of free-ranging predators on artificial snakes with triangular-shaped heads against the pressure on replicas with narrow heads. Snakes of both head types had either zigzag patterned bodies, typical of European vipers, or plain (patternless) bodies. Plain snakes with narrower Colubrid-like heads suffered significantly higher predation by raptors than snakes with triangular-shaped heads. Head shape did not, however, have an additive effect on survival in zigzag-patterned snakes, suggesting that species which differ from vipers in colouration and pattern would benefit most from behavioural mimicry. Our results demonstrate that the triangular head shape typical of vipers can act as a warning signal to predators. We suggest that head-shape mimicry may be a more common phenomenon among more diverse taxa than is currently recognised.     

Bile acid-cysteamine conjugates: structural properties, gelation, and toxicity evaluation

Design, synthesis, and characterization of six novel bile acid-cysteamine conjugates together with investigation of their structural studies, gelation properties, and preliminary toxicity evaluation, are reported. Solid state properties of selected compounds were studied by means of X-ray diffraction and (13)C CPMAS NMR spectroscopy. N-(2-thioethyl)-3α,7α,12α-trihydroxy-5β-cholan-24-amide was shown to exhibit (pseudo)polymorphism, and a single crystal structure of its non-stoichiometric hydrate is reported herein. Cholyl and dehydrocholyl derivatives bearing three functionalities in their steroidal backbone were shown to undergo self-assembly leading to gelation in certain organic solvents. Preliminary morphology studies of the formed gels by scanning electron microscopy (SEM) were performed. The standard model mouse fibroblast cell line together with the MTT and NR tests were utilized for evaluating the toxicity of the prepared compounds. Lithocholyl, ursodeoxycholyl, and dehydrocholyl derivatives turned out to be relatively non-toxic in the conditions studied.     

Structural studies of five novel bile acid-4-aminopyridine conjugates

Synthesis and solid-state structural characterization of five bile acid amides of 4-aminopyridine (4-AP) are reported. Systematic crystallization experiments revealed a number of structural modifications and/or solvate/hydrate systems for these conjugates. Particularly, cholic acid conjugate exhibited five distinct structure modifications, including one anhydrous form, mono- and dihydrates, as well as ethanol and 2-butanol solvates. The obtained crystal forms were examined extensively with various analytical methods, including solid-state NMR, Raman, and IR spectroscopies, powder and single crystal X-ray diffraction methods, thermogravimetry, and differential scanning calorimetry. After releasing their crystal solvent molecules, the resulted non-solvated structure forms showed 50-75°C higher melting points than corresponding bile acids, and thermal degradation occurred for all conjugates at about 300-330°C. Moreover, the single crystal X-ray structure of the ursodeoxycholic acid-4-aminopyridine conjugate is reported.     

Contribution of deaths related to alcohol use of socioeconomic variation in mortality: register based follow up study.

OBJECTIVE: To estimate the contribution of excessive alcohol use to socioeconomic variation in mortality among men and women in Finland. DESIGN: Register based follow up study. SUBJECTS: The population covered by the 1985 and 1990 censuses, aged > or = 20 in the follow up period 1987-93. MAIN OUTCOME MEASURES: Total mortality and alcohol related mortality from all causes, from diseases, and from accidents and violence according to socioeconomic position. The excess mortality among other classes compared with upper non-manual employees and differences in life expectancy between the classes were used to measure mortality differentials. RESULTS: Alcohol related mortality constituted 11% of all mortality among men aged > or = 20 and 2% among women and was higher among manual workers than among other classes. It accounted for 14% of the excess all cause mortality among manual workers over upper non-manual employees among men and 4% among women and for 24% and 9% of the differences in life expectancy, respectively. Half of the excess mortality from accidents and violence among male manual workers and 38% among female manual workers was accounted for by alcohol related deaths, whereas in diseases the role of alcohol was modest. The contribution of alcohol related deaths to relative mortality differentials weakened with age. CONCLUSIONS: Class differentials in alcohol related mortality are an important factor in the socioeconomic mortality differentials in Finland, especially among men, among younger age groups, and in mortality from accidents and violence.     

Effects of Inactivation and Constitutive Expression of the Unfolded- Protein Response Pathway on Protein Production in the Yeast Saccharomyces cerevisiae

One strategy to obtain better yields of secreted proteins has been overexpression of single endoplasmic reticulum-resident foldases or chaperones. We report here that manipulation of the unfolded-protein response (UPR) pathway regulator, HAC1, affects production of both native and foreign proteins in the yeast Saccharomyces cerevisiae. The effects of HAC1 deletion and overexpression on the production of a native protein, invertase, and two foreign proteins, Bacillus amyloliquefaciens α-amylase and Trichoderma reesei endoglucanase EGI, were studied. Disruption of HAC1 caused decreases in the secretion of both α-amylase (70 to 75% reduction) and EGI (40 to 50% reduction) compared to the secretion by the parental strain. Constitutive overexpression of HAC1 caused a 70% increase in α-amylase secretion but had no effect on EGI secretion. The invertase levels were twofold higher in the strain overexpressing HAC1. Also, the effect of the active form of T. reesei hac1 was tested in S. cerevisiae. hac1 expression caused a 2.4-fold increase in the secretion of α-amylase in S. cerevisiae and also slight increases in invertase and total protein production. Overexpression of both S. cerevisiae HAC1 and T. reesei hac1 caused an increase in the expression of the known UPR target gene KAR2 at early time points during cultivation.     

In vivo FLIM-FRET measurements of recombinant proteins expressed in filamentous fungi

Fluorescence imaging techniques are extremely powerful tools in cell biology, providing valuable insights into the structure and function of biomolecules in their native environments. In particular, the use of Förster resonance energy transfer (FRET) has become increasingly important to obtain information on interactions on the nanoscale, in turn providing insights into molecular behaviour inside living cells. This review describes the basic principles of FRET and fluorescence lifetime imaging microscopy (FLIM) and their application in analyses of protein interactions inside living fungal cells.     

Antimycin A-producing nonphytopathogenic Streptomyces turgidiscabies from potato

Aim:  To detect if substances with mammalian cell toxicity are produced by Streptomyces turgidiscabies and Streptomyces scabiei isolated from potato scab lesions. Methods and Results:  In vitro cultures of phytopathogenic and nonphytopathogenic strains of S. scabiei and S. turgidiscabies, isolated from scab lesions of potato tubers originating from nine different cultivars from Finland and Sweden, were tested for toxicity using the rapid spermatozoan motility inhibition assay, previously shown useful in the detection of many different Streptomyces toxins and antimicrobial compounds. Purified toxins were used as reference. Three nonphytopathogenic strains of S. turgidiscabies were found to produce antimycin A when cultured on solid medium. Conclusions:  Boar sperm-motility-inhibiting substances are produced by strains of S. turgidiscabies and S. scabiei. The most powerful inhibitory substance, produced by three nonphytopathogenic S. turgidiscabies strains, was identified as antimycin A. The phytotoxic compounds thaxtomin A and concanamycin A did not inhibit sperm motility even at high doses. Significance and Impact of the Study:  The presence of antimycin A-producing Streptomyces strains, nonpathogenic to potato, was unexpected but important, considering the high mammalian toxicity of this cytochrome bc-blocking antibiotic.     

A novel gene family in moss (Physcomitrella patens) shows sequence homology and a phylogenetic relationship with the TIR-NBS class of plant disease resistance genes

Plant disease resistance (R) genes encode proteins in which several motifs of the nucleotide-binding region (NBS) are highly conserved. Using degenerate primers designed according to the kinase 1 (P-loop) and hydrophobic (HD) motifs of the R gene NBS domains, homologous sequences were cloned from moss (Physcomitrella patens; phylum Bryophyta) representing an ancient nonvascular plant. A novel gene family (PpC) with at least eight homologous members was found. Expression of five members was detected. The level of expression was dependent on the developmental stage of moss, being higher in the gametophyte tissue than in the protonema tissue. The PpCs contained the conserved motifs characteristic of the NBS regions of R genes, and a kinase domain was found upstream from the NBS region. Phylogenetic analysis using the deduced NBS amino acid sequences of the PpCs and the plant genes available in databanks indicated that the PpCs show the closest relationship with the TIR-NBS class of R genes. No significant similarity to plant genes other than R genes was observed. These findings shed novel light on the evolutionary history of the R gene families, suggesting that the NBS region characteristic of the TIR-NBS class of R-like genes evolved prior to the evolutionary differentiation of vascular and nonvascular plants.     

Finnish quality assurance programme for biological monitoring of organic solvents

The FIOH quality assurance programme for organic solvents and their metabolites consists of analyses for 2,5-hexadione, phenol, mandelic acid, methylenedianiline, methylhippuric acid, trans,trans-muconic acid and trichloroacetic acid in urine, and creatinine and relative density for standardisation. Four times a year two levels of spiked urine or urine specimens collected from occupationally exposed workers are distributed to the participants in 22 countries. RSD and recovery were studied during 1997-2000. Average RSDs of all participants varied between 23 and 56% and were clearly dependent on the analytical method used and the concentration level of the samples. Since 1997 the target values have been determined in reference laboratories for five of the analytes. Lower RSDs (9-21%) and good recoveries were obtained for all analytes in these laboratories, indicating that good performance can be achieved even in the complex analyses performed in biological monitoring of exposure to industrial chemicals.     

Potyviral 6K2 protein long-distance movement and symptom-induction functions are independent and host-specific

Deletion of various portions, or insertion of six histidine residues (6xHis) into various positions of the membrane-bound 6K2 protein (53 amino acids) of Potato virus A (PVA, genus Potyvirus), inhibited systemic infection in Nicotiana tabacum and N. benthamiana plants. However, a spontaneous mutation (Gly2Cys) that occurred in 6K2 adjacent to the 6xHis insert placed between Ser1 and Gly2 enabled systemic infection in a single N. benthamiana plant. No symptoms were observed, but virus titers were similar to the symptom-inducing wild-type (wt) PVA. N. tabacum plants were not systemically infected, albeit virus propagation was observed in inoculated protoplasts. The 6xHis/Gly2Cys mutant was reconstructed in vitro and serially propagated by mechanical inoculation in N. benthamiana. Following the third passage, a novel viral mutant appeared, lacking the last four His residues of the insert, as well as the Gly2 and Thr3 of 6K2. It infected N. tabacum plants systemically, and in the systemically infected N. benthamiana leaves, vein chlorosis and mild yellowing symptoms were observed, typical of wt PVA infection. The mutant virus accumulated to titers similar to wt PVA in both hosts. These results show that the PVA 6K2 protein affects viral long-distance movement and symptom induction independently and in a host-specific manner.