Influence of humic acid molecular fractions on growth and development of soybean seedlings under salt stress

In the present study, the influence of humic acid (HA) molecular fractions (HA?<?30 kDa and HA?>?30 kDa) on enhancing the tolerance of seedlings of soybean [Glycine max (L.) Merr.] Progres and Nawiko cultivars to salt stress (50 mM NaCl) was investigated. HA were extracted from mountain fen soil and then were separated into two molecular fractions by membrane filtration and characterized by diffusion coefficient (D_app), electrolytic conductivity (κ) and electrophoretic mobility (U_e). The following biometric parameters of tested plants were determined: total leaf area, height of plants, fresh and dry mass of the over ground part and roots as well as length of shoots cells and length of stomas. The chlorophyll content in ground tissue as well as the macro and microelements content in tested plants also were determined. The results showed that the κ, U_e and D_app for HA?>?30 kDa were lower than these for HA?<?30 kDa. Adding NaCl caused increase κ and decrease D_app and U_e. The salt stress caused a major decrease in biometric parameters in tested plants. HA?>?30 kDa reduced the uptake of macro and microelements in the soybean Progres cultivar. In soybean Nawiko cultivar, it caused significant uptake of Fe and Zn. Soybean cultivars showed strong reaction to salt stress. HA molecular fractions reduced or eliminated the influence of the salt stress. However, HA?>?30 kDa was more effective than HA?<?30 kDa, due to its properties.     

Survey for Zoonotic Microsporidian Pathogens in Wild Living Urban Rooks (Corvus frugilegus)

Microsporidia are opportunistic pathogens in nature infecting all animal phyla. There is a potential risk of microsporidian spores transmission from urban rooks inhabiting some metropolitan cities to people through casual interactions. The aim of this study was to identify microsporidia species in the droppings of rooks in Wroclaw, Poland. A total of 15 collective sets of droppings were examined using nested‐PCR method. Amplification of ITS rRNA gene revealed the presence of Enterocytozoon bieneusi D, Peru 6, and Encephalitozoon hellem 1A genotypes. This study indicates that excreta of urban rooks can be an important source of human infection with these pathogens.     

Physiological Condition of Juvenile Wading Birds in Relation to Multiple Landscape Stressors in the Florida Everglades: Effects of Hydrology,Prey Availability,and Mercury Bioaccumulation

The physiological condition of juvenile birds can be influenced by multiple ecological stressors, and few studies have concurrently considered the effects of environmental contaminants in combination with ecological attributes that can influence foraging conditions and prey availability. Using three temporally distinct indices of physiological condition, we compared the physiological response of nestling great egrets (Ardea alba) and white ibises (Eudocimus albus) to changing prey availability, hydrology (water depth, recession rate), and mercury exposure in the Florida Everglades. We found that the physiological response of chicks varied between species and among environmental variables. Chick body condition (short-term index) and fecal corticosterone levels (medium-term) were influenced by wetland water depth, prey availability, region, and age, but not by mercury contamination. However, mercury exposure did influence heat shock protein 70 (HSP70) in egret chicks, indicating a longer-term physiological response to contamination. Our results indicate that the physiological condition of egret and ibis chicks were influenced by several environmental stressors, and the time frame of the effect may depend on the specialized foraging behavior of the adults provisioning the chicks.     

The activity of alkaline phosphatase in the process of regeneration of rat liver.

Using GOMORI'S technique, the present authors investigated the dynamics of the alkaline phosphatase activity in the process of liver regeneration after partial hepatectomy. In all 80 rats of the Wistar strain were subjected to experiment, 60 to 75% of the liver parenchyma being removed from each of them. In the course of regeneration a gradual increase in the enzyme activity was observed within the first 48 hours following the operation. This was succeeded by a slow decline of the activity, and after the 25th day after the operation the reaction intensity resembled that recorded for the control animals. It was also ascertained that the fatty degeneration of the liver noted in the initial period of regeneration does not inhibit the activity of alkaline phosphatase.     

Melatonin,immune function and aging

Aging is associated with a decline in immune function (immunosenescence), a situation known to correlate with increased incidence of cancer, infectious and degenerative diseases. Innate, cellular and humoral immunity all exhibit increased deterioration with age. A decrease in functional competence of individual natural killer (NK) cells is found with advancing age. Macrophages and granulocytes show functional decline in aging as evidenced by their diminished phagocytic activity and impairment of superoxide generation. There is also marked shift in cytokine profile as age advances, e.g., CD3+ and CD4+ cells decline in number whereas CD8+ cells increase in elderly individuals. A decline in organ specific antibodies occurs causing reduced humoral responsiveness. Circulating melatonin decreases with age and in recent years much interest has been focused on its immunomodulatory effect. Melatonin stimulates the production of progenitor cells for granulocytes-macrophages. It also stimulates the production of NK cells and CD4+ cells and inhibits CD8+ cells. The production and release of various cytokines from NK cells and T-helper lymphocytes also are enhanced by melatonin. Melatonin presumably regulates immune function by acting on the immune-opioid network, by affecting G protein-cAMP signal pathway and by regulating intracellular glutathione levels. Melatonin has the potential therapeutic value to enhance immune function in aged individuals and in patients in an immunocompromised state.     

Hormonal Effects on Calcium Metabolism in Crustacea

Cyclic shifts of calcium in the exoskeleton and soft tissues,as they are related to the intermolt cycle in crayfish, arereviewed. Regulatory factors, derived from the eyestalk, influencelevels of exoskeletal calcium; eyestalk extracts prepared fromanimals in premolt decrease shell calcium, while reciprocallyextracts from animals in intermolt increase it when these hormonalsources are injected into animals in the premolt stage (D₀-D₄). In addition, premolt eyestalk extract results in an increasein gastrolith calcium. In the exchange of calcium between theanimal and its environment there is evidence for differentialdepositionof recently available calcium in the exoskeleton. Further, intermoltand early premolt animals maintained in Ca⁴⁵-labelled waterfor 15 days concentrate it 4 and 3—fold in the exoskeletonand stomach, respectively. However, removal of a molt-inhibitingfactor through ablation of eyestalks results in a 20 and 40—foldincrease in incorporation inthese same sites relative to environmentalconcentrations. Treatment with mammalian parathyroid extract mobilizes bothexoskeletal and gastric calciumand leads to a rise in bloodcalcium. However, there is little or no effect on levels ofexoskeletal citric acid. Further, citric acid is higher in thecrayfish carapace during stage C, the period of mineralization,than in stage D, the period of demineralization. There are both similarities and differences between the effectsof crustacean and mammalianregulating factors with respect tothe direction and extent of mineralization. Biochemical studiesshould elucidate the mechanisms regulated by these hormones.     

The partition matrix: exploring variable phylogenetic signals along nucleotide sequence alignments

The partition matrix is a graphical tool for comparative analysis of nucleotide sequences following alignment. It is particularly useful for investigating the divergent phylogenies of sequence regions undergoing reticulate evolution. A partition matrix is generated by determining the consistency of the parsimoniously informative sites in a set of aligned sequences with the binary partitions inferred from the sequences. Since the linear order of sites is maintained, the matrix can be used to assess whether the distribution of sites either supporting or conflicting with particular partitions changes along the length of the alignment. The usefulness of the matrix in allowing visual identification of differences in evolutionary history among regions depends on the order in which partitions are shown; several suitable ordering schemes are proposed. We demonstrate the use of the partition matrix in interpreting the evolution of the pseudoautosomal boundary region on the sex chromosome of catarrhine primates. Its routine use should help to avoid attempts to derive single phylogenies from sequences whose evolution has been reticulate and to identify the gene conversion or recombination events underlying the reticulation. The method is relatively fast. It is exploratory, and it can form the basis for more formal analysis, which we discuss.      

Positive selection and sequence rearrangements generate extensive polymorphism in the gamete recognition protein bindin

Bindin is a gamete recognition protein of sea urchins that mediates species-specific attachment of sperm to an egg-surface receptor during fertilization. Sequences of bindin from closely related urchins show fixed species-specific differences. Within species, highly polymorphic bindin alleles result from point substitution, insertion/deletion, and recombination. Since speciation, positive selection favoring allelic variants has generated diversity in bindin polypeptides. Intraspecific bindin variation can be tolerated by the egg receptor, which suggests functional parallels between this system and other flexible recognition systems, including immune recognition. These results show that polymorphism in mate recognition loci required for rapid evolution of sexual isolation can arise within natural populations.      

STRUCTURE AND FUNCTION OF THE BRISTLES OF PEDIASTRUM BORYANUM (CHLOROPHYTA)1

Tufts of long delicate bristles were detected on mature colonies of Pediastrum boryanum (Turp.) Meneghini. The bristles are not uniform in length and can exceed 100 μm. Bristle number per tuft can exceed eighty. Ultrastructure studies revealed that tufts are an aggregate of hexagonal tubules arranged in staggered rows. Each hexagonal tubule has an inner diameter of 6 nm and is made up of six interconnected subunits 4 nm in diameter that are shared by adjoining tubules. The bristles can be easily removed from mature colonies with a vortex stirrer. Removal of bristles from mature colonies in culture results in the loss of buoyancy and subsequent settling to the bottom of the flask.