A Simple Survival Model for Combined Action of Two Damaging Agents

The aim of this study was mathematical formalization of the development of two damage processes in response to the combined action of two different damaging agents. The model allows to obtain the parametric family of distributions for the life-span when the organism's death is due to joint effect of two damage processes. Differing by their probabilistic meaning the notions of a priori (M (t)) and a posteriori (M(y)) conditional mean contributions of each damage process to the final effect of combined injury are introduced. The formulas permitting to compute the M and M values on the basis of survival data parametric analysis are given.     

Self-association of human erythrocyte phosphofructokinase. Kinetic behaviour in dependence on enzyme concentration and mode of association.

The kinetic behaviour of human erythrocyte phosphofructokinase has been analyzed over a relative wide range of enzyme concentration (0.01 -- 1.7 mug/ml). The kinetic cooperativity which becomes apparent when the enzymic reaction rate is plotted versus the fructose 6-phosphate concentration decreases with increasing enzyme concentration. Simultaneously, a decrease of the half-saturation concentration for fructose 6-phosphate [S]0.5 is observed. Maximum velocity passes through a maximum at increasing enzyme concentrations. Sets of curves representing specific enzymic activity of phosphofructokinase versus enzyme concentration obtained at various fixed concentrations of fructose 6-phosphate and ATP are analyzed. The shapes of these curves are interpreted in terms of an association model of human erythrocyte phosphofructokinase, in which an inactive dimer (Mr 190000) and active multimers of the dimeric form are involved. The conclusion is drawn that the sigmoidal shape of the plots of the enzymic reaction rate versus fructose 6-phosphate concentration is partially caused by a displacement of the equilibrium between different states of association of phosphofructokinase to multimers by this substrate. On the other hand, the inhibition of the enzyme by high concentrations of ATP may be partially caused by a shift of this equilibrium to the state of the inactive dimer.     

Mechanism of the mutagenic action of hydroxylamine. IX. The UV-induced cleavage of the N-O bond in N4-hydroxy-and N4-methoxycytidine and N6-methoxyadenosine.

The principal UV-induced (lambda = 2546nm) reaction of N4-hydroxy- and N4methoxycytidines and N6-methoxyadenosine in neutral aqueous solutions is cleavage of the exocyclic N-O bond with the respective formation of cytidine and adenosine. Quantum yields are 2.8x10(-3) and 2.2x10(-3) M/E for the first two compounds and 9.1x10(-3) M/E for N6-methoxyadenosine.     

The environmental fate and behaviour of antifouling paint booster biocides: A review

Antifouling paint booster biocides are a group of organic compounds added to antifouling paints to improve their efficacy. They have become prevalent since the requirement for alternative antifouling paints formulations for small boats (< 25 m). This need followed a ban on the use of triorganotin biocides in antifouling paints for small boats, in the late 1980's. Worldwide, around eighteen compounds are currently used as antifouling biocides, viz. benzmethylamide, chlorothalonil, copper pyrithione, dichlofluanid, diuron, fluorofolpet, Irgarol 1051, Sea‐Nine 211, Mancozeb, Polyphase, pyridine‐triphenyl‐borane, TCMS (2,3,5,6‐tetrachloro‐4‐methylsulfonyl) pyridine, TCMTB [2‐(thiocyanomethylthio)benzothia‐zole], Thiram, tolyfluanid, zinc pyrithione (ZPT), ziram and Zineb. Any booster biocide released into the environment is subjected to a complex set of processes. These processes include transport mechanisms, transformation, degradation, cross media partitioning, and bioaccumulation. This paper reviews the fate and behaviour data currently available in the public domain concerning antifouling paint booster biocides.     

Distribution of carpenter-moths (Lepidoptera, Cossidae) in the Palaearctic deserts

Specific features of the carpenter-moths (Cossidae) distribution in the Palaearctic deserts are considered. The Palaearctic frontier was delimited to the Arabian Peninsula (the eastern and northern parts of Arabia are attributed to the Palaearctic Region; Yemen, southwestern Saudi Arabia, and southernmost Iran belong to the Afrotropical Region). Cossidae are highly endemic to arid areas. Some Palaearctic carpenter-moth genera penetrate to Africa southward of the Sahara Desert (an important characteristic distinguishing them from most of the other Lepidoptera). The local faunas of the Palaearctic deserts are united into 4 groups: the Sahara-Arabian-Southern-Iranian, Central-Asian-Kazakhstanian, Western-Gobian, and Eastern-Gobian. In the Eastern Gobi Desert, the fauna is the most specific; it should be considered as a separate zoogeographical subregion.     

Hormonal influence on antimicrobial peptide synthesis by fat body cells of a blowfly, Calliphora vicina R.-D. (Diptera, Calliphoridae)

The mechanism of septic induction of antimicrobial peptide synthesis in insects is well reported in current papers. On the contrary, there is little data on aseptic, particularly hormonal, regulation of immune defense. Insect neuroendocrinology traditionally considers hormones as regulators of development and reproduction, focusing less attention on their role in regulation of defense reactions. In the present study, the direct influence of ecdysones, adipokinetic hormone, and biogenic amines on antimicrobial peptide synthesis in isolated fat body cells of Calliphora vicina was studied. According to the results, low concentrations of α- and β-ecdysones and high doses of adipokinetic hormone and octopamine can stimulate the fat body activity in vitro. Thus, these hormones are key mediators of the adaptive syndrome, hormonal activation of endogenic antibiotic synthesis which probably takes place in response to extreme stimuli.     

Transcriptional profiling of epigenetic regulators in somatic embryos during temperature induced formation of an epigenetic memory in Norway spruce

Planta - A significant number of epigenetic regulators were differentially expressed during embryogenesis at different epitype-inducing conditions. Our results support that methylation of DNA and...