Inhibition of the enzymatic hydration of the epoxide HEOM in insects

Enzymatic epoxide hydration, a significant mechanism in the regulation of insect development and in the detoxication of certain cyclodiene insecticides, has been investigated in vitro in the blowfly, Calliphora erythrocephala, the southern armyworm, Prodenia eridania, and the Madagascar cockroach, Gromphadorhina portentosa. Characterization of the hydrases involved in cyclodiene epoxide hydration has been achieved using as substrate a cyclodiene insecticide (HEOM) susceptible to enzymatic epoxide ring cleavage. The enzymes, which are microsomal but different from the oxidases, are inhibited in varying degrees by microsomal oxidase inhibitors as well as by certain epoxides, esterase inhibitors and compounds with reported juvenilizing ability. Group-bulk and electronegative effects are important requirements for HEOM-hydrase inhibition, the best inhibitor of the system being 1,1,1-trichloro-2,3-epoxypropane. Differences between the structural requirements for HEOM-hydrase inhibition and those for inhibition of the epoxide hydrase responsible for the degradation of juvenile hormone are discussed.     

Impact of inducing general anesthesia with Propiscin (etomidate) on the physiology and health of European perch (<Emphasis Type="Italic">Perca fluviatilis</Emphasis> L.)

The aim of the study was to describe the course and timing of the different stages of anesthesia induced with Propiscin (etomidate) on juvenile European perch (experiment I) and to describe the effect of immersing specimens of this species had on selected hematological and biochemical parameters (experiment II). The study was conducted on material with body weights (BW) of 162.98 (experiment I) and 171.60 g (experiment II). In experiment I, general anesthesia was induced with two different anesthetic concentrations (1 or 2 ml l^?1; anesthesia time 10 min). In experiment II, blood was drawn for hematological and biochemical analyses from the fish that had been exposed to anesthetic immersion baths with two different concentrations of Propiscin (1 and 2 ml l^?1) and for different exposure times (3 and 10 min). Blood samples were collected immediately following immersion (0 h) and 24 h later (24 h). Specimens that were immersed at the higher concentration of anesthetic achieved subsequent stages of general anesthesia two times faster (P ≤ 0.05). However, during recovery, some statistically significant differences were observed, but these lasted only until stage I was achieved. Among the hematological parameters (0 h), significant differences were observed in hematocrit (HCT) and mean corpuscular volume (MCV), while among the biochemical determinations (0 h), statistically significant differences were noted in the concentrations of glucose, calcium, lactate, and ammonia. After 24 h, the levels of these parameters in all fish groups returned to initial values. The hematological and biochemical tests conducted permit concluding that the anesthetic tested, at the concentrations (1 and 2 ml l^?1) and the exposure times of up to 10 min at which it was tested, is safe and can be used successfully to induce general anesthesia in perch.     

Habitat prediction model for three-toed woodpecker and its implications for the conservation of biologically valuable forests

We studied habitat selection of three-toed woodpecker (TTW) in relation to forest structural variables, habitat types and hydrological conditions in north-eastern Poland. Based on known locations of 34 breeding pairs and the data on location of forest areas with high conservation value (referred to as Biologically Important Forests), we created a habitat prediction model for TTW using a Maxent algorithm. We found that this species most often selected breeding sites characterized by high contribution of old-growth stands with uneven vertical structure and considerable amount of very old trees of previous generations, as well as boreal spruce-dominated bogs and riverine forests. Such sites were preferred regardless of their actual protection status, which leads to the following conclusion: although existing forest reserves are very important to three-toed woodpecker, suitable habitats with similar characteristics can still be found outside protected areas and are also utilized by the species. However, such sites outside reserves are threatened by fragmentation due to timber extraction. Therefore it is recommended to protect these sites by either including them into existing reserves or putting them under special management schemes.     

Lodgepole pine: the first evidence of seed-based somatic embryogenesis and the expression of embryogenesis marker genes in shoot bud cultures of adult trees

Of the various alternatives for cloning elite conifers, somatic embryogenesis (SE) appears to be the best option. In recent years, significant areas of lodgepole pine (Pinus contorta) forest have been devastated by the mountain pine beetle (MPB) in Western Canada. In an attempt to establish an SE propagation system for MPB-resistant lodgepole pine, several families displaying varying levels of resistance were selected for experimentation involving shoot bud and immature seed explants. In bud cultures, eight embryogenic lines were induced from 2 of 15 genotypes following various treatments. Genotype had an important influence on embryogenic culture initiation, and this effect was consistent over time. These lines were identified by microscopic observation and genetic markers. Despite the abundance of early somatic embryos, the cultures have yet to develop into mature embryos. In contrast, immature zygotic embryos (ZEs) cultured from megagametophytes initiated SE at an early dominance stage via nodule-type callus in 1 of 10 genotypes. As part of the study, putative embryogenesis-specific genes, WOX2 (WUSCHELL homeobox 2) and HAP3A, were analyzed in cultures of both shoot bud explants and ZEs. On the basis of these analyses, we postulate that PcHAP3A was expressed mainly in callus and may be involved in cell division, whereas WOX2 was expressed mainly in embryonal mass (EM)-like tissues. The findings from this study, based on molecular assessment, suggest that the cell lines derived from bud cultures were truly EM. Moreover, these experimental observations suggest that PcWOX2 could be used as an early genetic marker to discriminate embryogenic cultures from callus.     

Spectral and inhibitory interactions of methylenedioxyphenyl compounds with southern armyworm (Spodoptera eridania) midgut microsomes

Characteristics of the Type III optical difference spectra of 13 methylenedioxyphenyl compounds in NADPH-fortified armyworm midgut microsomes varied with the nature of the substituents in the aromatic ring. Compounds with electron-donating substituents yielded spectra with large $\text{427}\text{458}\text{nm}$ peak ratios, whereas those with electron-withdrawing groups exhibited low $\text{427}\text{458}\text{nm}$ peak ratios. Small amounts of carbon monoxide were generated during incubation of the 4,5-dihalo derivatives with midgut microsomes, and cis- and trans-methylenedioxycyclohexanes exhibited spectra with a major Soret peak at about 430 nm and a very weak absorbance maximum at about 480 nm. Formation of the Type III spectral complex occurred very rapidly and was associated with a marked decrease (up to 72%) in cytochrome P-450 levels as measured by carbon monoxide binding. Although a 24% reduction of cytochrome P-450 was observed in the absence of any measureable 458-nm spectral complex a linear relationship existed between further decreases in the cytochrome and the increase in Type III complex formation (458 nm). Inhibitory potencies of the compounds towards aldrin epoxidase and benzopyrene hydroxylase activities were not clearly correlated with either spectral complex formation or decrease in cytochrome P-450 and it is apparent that different factors are involved in the inhibition of different monooxygenase reactions.     

Edible Plants Enriched with Selenium

Selenium （Se） is an important element from the environmental and biological point of view. In the world, deficiency of Se in a diet occurs more often and nutritional supplements are recommended.The ability of several plants to accumulate and transform inorganic Se forms into its bioactive organic compounds has important implications for human nutrition and health. This work gives a brief overview of the study carried out to characterize Se species produced by different enriched edible plants which were grown in the presence of different Se species.     

Seasonal changes of perlite–peat substrate properties in seedlings grown in different sized container trays

New Forests - Cultivation of seedlings in trays requires the use of specifically developed substrates. This study presents the results of the analyses of selected physical and mechanical parameters...