Membrane proteins and squalene-hydrosqualene profile in methanoarchaeon Methanothermobacter thermautotrophicus resistant to N,N′-dicyclohexylcarbodiimide

The biochemical basis of a defective bioenergetic system was attempted to be determined in N,N'-dicyclohexylcarbodiimide (DCCD)-resistant mutant of Methanothermobacter thermautotrophicus. Components participating in the maintenance of methanoarchaeal membrane structure and function, such as the composition of the mixture of squalene and its hydrosqualene derivatives and also properties of membrane-associated proteins were compared in wild-type and mutant cells. The impairment of the bioenergetic system in DCCD-resistant mutant was detectable in the membrane-protein profile; it was also accompanied by changes in proportions of squalene-hydrosqualenes.     

Antilaminaribioside and antichitobioside antibodies in inflammatory bowel disease

Testing antilaminaribioside (ALCA) and antichitobioside (ACCA) antibodies in 89 Crohn's disease (CD), 31 ulcerative colitis (UC) and 50 controls, mean values were 38.6 and 53.0 ELISA units for CD, 34.0 and 32.6 for UC, 34.5 and 36.4 for controls, respectively. There was no significant difference of ALCA values between CD and UC (p = 0.401), CD and control subjects (p = 0.698) or UC and controls (p = 0.898). ACCA were significantly higher in CD compared with UC (p = 0.011) but not with the controls (p = 0.095). No significant difference of ACCA values between UC and controls (p = 0.107) was found. ALCA and ACCA values significantly correlated in CD (r = 0.548, p < 10(-4)) and UC (r = 0.885, p < 10(-4)) but not in controls (r = 0.153, p = 0.287). The positive predictive value for CD was only 20 (ALCA) and 8 % (ACCA), the negative ones (to exclude CD) 25 (ALCA) and 86 % (ACCA). Small and/or large bowel involvement or disease type (i.e. stenosing, perforating or inflammatory) of CD did not differ in the two values. The idea that ALCA and ACCA may be useful either to differentiate between CD, UC and healthy subjects or to stratify CD was not confirmed.     

Morphological variability in selected heterocystous cyanobacterial strains as a response to varied temperature, light intensity and medium composition

The effect of temperature, light and nutrient composition on morphological traits was determined in seven nostocacean cyanobacteria (Anabaena planctonica, A. sphaerica var. conoidea, A. spiroides, Aphanizomenon gracile, Nostoc sp., Scytonema sp., and Tolypothrix sp.). Their morphological variability was high but only some of the features showed changes reflecting varied growth conditions. The frequency of heterocyst occurrence decreased with increasing nitrogen concentration. Within the range studied, the effect of temperature on heterocyst frequency of Tolypothrix sp. and planktonic Anabaena strains could be fitted by a normal curve with a clear optimum while linear correlation was found in Aphanizomenon gracile. T-and S-type branching was observed in both Scytonema sp. and Tolypothrix sp. strains. T-type branching was found to be markedly dependent on nitrogen concentration. The abundance of necridic cells of Tolypothrix sp. increased linearly with temperature and light intensity. Regularity of trichome coiling of A. spiroides depended on culture medium, suggesting that nutrient composition may be the main controlling factor. In contrast, the effect of the experimental conditions on the dimensions of vegetative cells and heterocysts was weak. Their variability was markedly higher within each experimental treatment than between treatments.     

Control and prediction of the course of brewery fermentations by gravimetric analysis

A simple, fast and cheap test suitable for predicting the course of brewery fermentations based on mass analysis is described and its efficiency is evaluated. Compared to commonly used yeast vitality tests, this analysis takes into account wort composition and other factors that influence fermentation performance. It can be used to predict the shape of the fermentation curve in brewery fermentations and in research and development projects concerning yeast vitality, fermentation conditions and wort composition. It can also be a useful tool for homebrewers to control their fermentations.     

Heavy-metal stress induced accumulation of chitinase isoforms in plants

Plant chitinases belong to so-called pathogenesis related proteins and have mostly been detected in plants exposed to phytopathogenic viruses, bacteria or fungi. A few studies revealed that they might also be involved in plant defence against heavy metals. This work was undertaken to monitor the accumulation of chitinases in a set of heavy-metal stressed plants and bring evidence on their involvement during this kind of stress. Roots of different plant species including Vicia faba cvs. Aštar and Piešťansky, Pisum sativum, Hordeum vulgare, Zea mays and Glycine max were exposed to different concentrations of lead (300 and 500 mg l⁻¹ Pb²⁺), cadmium (100 and 300 mg l⁻¹ Cd²⁺) and arsenic (50 and 100 mg l⁻¹ As³⁺). In each case, the toxicity effects were reflected in root growth retardation to 80–10% of control values. The most tolerant were beans, most sensitive was barley. Extracts from the most stressed roots were further assayed for chitinase activity upon separation on polyacrylamide gels. Our data showed that in each combination of genotype and metal ion there were 2–5 different chitinase isoforms significantly responsive to toxic environment when compared with water-treated controls. This confirms that chitinases are components of plant defence against higher concentrations of heavy metals. In addition, accumulation of some isoforms in response to one but not to other metal ions suggests that these enzymes might also be involved in a more (metal) specific mechanism in affected plants and their biological role is more complex than expected.     

Composting of poultry manure and wheat straw in a closed reactor: optimum mixture ratio and evolution of parameters

The main objectives of this work were to investigate the evolution of some principal physico-chemical properties (temperature, carbon dioxide, oxygen, ammonia, pH, electrical conductivity, organic matter) and microbial population (mesophilic and thermophilic bacteria and fungi) during composting poultry manure with wheat straw in a reactor system, and to evaluate the optimum mixture ratio for organic substrate production. The experiments were carried out in four small laboratory reactors (1 l) and one large reactor (32 l) under adiabatic conditions over 14 days. During the process the highest temperature was 64.6°C, pH varied between 7.40 and 8.85, electrical conductivity varied between 3.50 and 4.31 dS m⁻¹ and the highest value of organic matter (dry weight) degradation was 47.6%. Mesophilic bacteria and fungi predominated in the beginning, and started the degradation with generation of metabolic heat. By increasing the temperature in reactors, the number of thermophilic microorganisms also increased, which resulted in faster degradation of substrate. The application of a closed reactor showed a rapid degradation of manure/straw mixture as well as a good control of the emissions of air polluting gases into atmosphere. The results showed that the ratio of manure to straw 5.25:1 (dry weight) was better for composting process than the other mixture ratios.     

Somatostatin-14 influences pituitary–ovarian axis in peripubertal rats

The effects of multiple somatostatin (SRIH-14) administration on the pituitary-ovarian axis were examined in peripubertal rats. Female Wistar rats received subcutaneously, two daily doses of 20 mug SRIH-14 per 100 g body weight (b.w.) for five consecutive days (from the 33rd to the 37th day of life). Follicle-stimulating (FSH), luteinizing (LH) and somatotropic (GH) cells were examined by the peroxidase-anti-peroxidase immunocytochemical method. Changes in cell volumes, volume densities and number per unit area (mm(2)) of FSH-, LH- and GH-immunoreactive cells were evaluated by stereology and morphometry. Serum FSH and LH levels were determined by RIA. Ovaries were analyzed by simple point counting of follicles. The volumes and volume densities of FSH-, LH- and GH-immunoreactive cells were significantly decreased while their numbers per mm(2) remained unchanged. SRIH-14 induced a significant decrease in serum FSH and LH levels. In the ovary, SRIH-14 induced an increase in the number of primordial follicles, followed by a reduction in the number of small healthy growing follicles and absence of preovulatory follicles. The number of atretic follicles was unchanged. We concluded that treatment with SRIH-14 during the peripubertal period markedly inhibited pituitary FSH, LH and GH cells. In the ovary, SRIH-14 acted by inhibiting folliculogenesis without affecting atretic processes.     

Cystatin B and its EPM1 mutants are polymeric and aggregate prone in vivo

Progressive myoclonus epilepsy type 1 (EPM1) is a neurodegenerative disease correlating with mutations of the cystatin B gene. Cystatin B is described as a monomeric protein with antiprotease function. This work shows that, in vivo, cystatin B has a polymeric structure, highly resistant to SDS, urea, boiling and sensitive to reducing agents and alkaline pH. Hydrogen peroxide increases the polymeric structure of the protein. Mass spectrometry analysis shows that the only component of the polymers is cystatin B. EPM1 mutants of cystatin B transfected in cultured cells are also polymeric. The banding pattern generated by a cysteine-minus mutant is different from that of the wild-type protein as it contains only monomers, dimers and some very high MW bands while misses components of MW intermediate between 25 and 250 kDa. Overexpression of wild-type or EPM1 mutants of cystatin B in neuroblastoma cells generates cytoplasmic aggregates. The cysteine-minus mutant is less prone to the formation of inclusion bodies. We conclude that cystatin B in vivo has a polymeric structure sensitive to the redox environment and that overexpression of the protein generates aggregates. This work describes a protein with a physiological role characterized by highly stable polymers prone to aggregate formation in vivo.     

UV light-induced DNA damage detection in the unicellular green alga <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis>

Exposure of cells to ultraviolet radiation (UVR) is one of the best studied and most used model system for the examination of the biological effects of DNA damage, its repair and tolerance. The major product after UVR treatment is cyclobutane pyrimidine dimer (TT, TC, CC). Pyrimidine dimers are repaired by a direct reversal called photoreactivation or by excision of damage in a process of nucleotide excision repair. Several methods have been developed for the detection and quantification of pyrimidine dimers in DNA. The technique of Small and Greimann, in which DNA is incubated with the pyrimidine dimer-specific endonuclease, was used for the analysis of mutant strains with impaired excision repair system of the unicellular green alga Chlamydomonas reinhardtii. Another method is based on the binding of specific monoclonal antibodies to pyrimidine dimers. The aim of our work was to compare these two techniques with the use of mutant strains of C. reinhardtii — uvsX1 and uvsX2 which are assumed to be deficient in DNA damage recognition. One of their traits was sensitivity to UVR which could be caused by breakdown of the excision repair pathway. The results suggest that the immuno-approach is suitable for the detection of DNA damage induced by UVR. Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia.     

Use of algae in the study of essential cell processes

Maintenance of genomic stability is of crucial importance for all living organisms. It is no surprise that during evolution, a series of highly selective and efficient systems to detect DNA damage and control its repair have evolved. To this end, signal transduction pathways are involved in pausing the cell division cycle to provide time for repair, and ultimately releasing the cell cycle from arrest. Genetic components of the damage and replication checkpoints have been identified and a working model is beginning to emerge. This area of biological inquiry has received a great deal of attention in the past decade with the realization that the underlying regulatory mechanisms controlling the cell cycle are conserved throughout eukaryotic evolution. Many of the key players in this response have structural and functional counterparts in species as diverse as yeast and human. In recent years attention has also been paid to the plant kingdom suggesting that checkpoint controls have been highly conserved during evolution. The unicellular green alga Chlamydomonas reinhardtii is a suitable model organism for the study of basic cellular processes including cell cycle regulation and DNA repair. To investigate how algal cells accomplish these tasks, we have isolated mutants in the recognition and repair of DNA damage or in the response to DNA damage. Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia.