Detection of lysozyme-like enzymatic activity secreted by an immune-responsive mosquito cell line

Using molecular approaches, we have recently shown that the C7-10 mosquito cell line from Aedes albopictus, and the Aag-2 line from Aedes aegypti, secrete a variety of immune peptides into the culture medium, including cecropins, defensins, transferrin, and lysozyme. The diversity of these peptides makes it difficult to quantify the relative activities of each molecule, because possible synergistic interactions may occur. Using a microtiter plate assay with live bacteria, we now show that C7-10 cells secrete an activity that is more potent against the Gram-positive bacterium, Micrococcus luteus, than against Gram-negative Escherichia coli. This lysozyme-like activity is accompanied by production of a lytic zone in an agarose plate assay containing commercially available, lyophilized M. luteus. Properties of the lysozyme-like activity from C7-10 cells included a broad pH optimum from 5.5 to 6.5, and heat-sensitivity above 42 degrees C. Amounts of secreted activity increased during the initial 24h of incubation with heat-killed bacteria. During this induction, lysozyme-like activity was found primarily in the cell culture supernatant.     

Circadian rhythms during cycling exercise and finger-tapping task

The aim of this study was to follow the circadian fluctuation of the spontaneous pedal rate and the motor spontaneous tempo (MST) in a sample of highly trained cyclists. Ten subjects performed five test sessions at various times of day. During each test session, subjects were required to perform (i) a finger-tapping task, in order to set the MST and (ii) a submaximal exercise on a cycle ergometer for 15 min at 50% of their W_max. For this exercise, pedal rate was freely chosen. Spontaneous pedal rate and heart rate (HR) were measured continuously.

The results demonstrated a circadian variation for mean oral temperature, HR, and MST. Under submaximal exercise conditions, HR showed no significant time-of-day influence although spontaneous pedal rate changed significantly throughout the day. Circadian rhythm of oral temperature and pedal rate were strongly correlated. Moreover, a significant positive correlation was found between MST and pedal rate. Both parameters may be controlled by a common brain oscillator. MST, rest HR, and pedal rate changes follow the rhythm of internal temperature, which is considered to be the major marker in chronobiology, therefore, if there is a relation between MST and pedal rate, we cannot rule out partial dependence of both parameters on body temperature.     

Agricultural Intensification and the Secondary Products Revolution Along the Jordan Rift

The ecological impacts of early agriculture in the Near East remained localized prior to the intensified production of derivative plant and animal products, beginning in the fourth millennium B.C. One aspect of this secondary products revolution (Sherratt, 1980a, 1983) involved the adoption of animal traction and increased production of rendered animal commodities (e.g., wool and dairy). However, most of the pervasive regional effects of this revolution followed from the domestication and increasingly intensive cultivation of orchard crops that generated marketable secondary products (e.g., olive oil, wine, and dried fruits) and encouraged widespread deforestation. In the southern Levant this revolution encouraged, and was encouraged by, the rise and fall of Bronze Age towns and their mercantile influences. Botanical and palynological data from the Jordan Rift reveal a complex discontinuous legacy of changes wrought by the secondary products revolution that have molded the agrarian ecology and anthropogenic landscapes characteristic of the region today.     

Mitochondrial dysfunctions during aging: vitamin E deficiency or caloric restriction--two different ways of modulating stress

Caloric restriction (CR), which has been demonstrated to offset the age-associated accrual of oxidative injury, involves a reduction in calory intake while maintaining adequate nutrition, preserves the activities of antioxidant enzymes in postmitotic tissues, maintains organ function, opposes the development of spontaneous diseases, and prolongs maximum life span in laboratory rodents. It has been proposed that reductions in Reactive Oxygen Species (ROS) production and cellular oxidative injury are central to the positive effects of CR. In the present investigation we studied the effect of CR and of a vitamin E deprived diet on mitochondrial structure and features in the liver of rats during aging, in order to ascertain the extent of modifications induced by these experimental conditions. CR rats displayed structural and functional mitochondrial properties (fatty acid pattern, respiratory chain activities, antioxidant levels, and hydroperoxide contents) similar to those of younger rats whilst vitamin E deficient rats appeared older than their own age. The mitochondria of the former, together with those of young rats, possessed the lowest Coenzyme Q₉, hydroperoxide, and cytochrome contents as well as a suitable fatty acid membrane composition. Our study confirms that CR is a valuable tool in limiting aging-related free-radical damage also at mitochondrial liver level.     

Effects of europium ions (Eu3+) on the distribution and related biological activities of elements in Lathyrus sativus L. roots

Scanning electron microscopic and energy-dispersive X-ray analyses were used to study the distributions of different types of elements in the epidermis, exodermis, endodermis, and vascular cylinder of the fracture face in the Lathyrus sativus L. roots in the presence or absence of Eu³⁺. Some index of the biological activity related to the elements binding with protein were determined also. The results showed that the tissular distributions of elements in the fracture face are different in the presence and absence of Eu³⁺. The atomic percentages of P, S, Ca, and Mn were influenced more than those of other elements. Eu³⁺ promoted the biological activities of various kinds of element. The one possible mechanism changing the biological activities was that the reaction of Eu³⁺ Eu²⁺ would influence the electron capture or transport in elements of binding protein. Another mechanism was that CaM-Ca²⁺ becoming CaM-Eu³⁺ through Eu³⁺ instead of Ca²⁺ would affect the biological activity of elements by regulating the Ca²⁺ level in the plant cell.     

Modeling of the phase equilibria of polystyrene in methylcyclohexane with semi-empirical quantum mechanical methods I

A method for calculating interaction parameters traditionally used in phase-equilibrium computations in low-molecular systems has been extended for the prediction of solvent activities of aromatic polymer solutions (polystyrene+methylcyclohexane). Using ethylbenzene as a model compound for the repeating unit of the polymer, the intermolecular interaction energies between the solvent molecule and the polymer were simulated. The semiempirical quantum chemical method AM1, and a method for sampling relevant internal orientations for a pair of molecules developed previously were used. Interaction energies are determined for three molecular pairs, the solvent and the model molecule, two solvent molecules and two model molecules, and used to calculated UNIQUAC interaction parameters, a _ij and a _ji . Using these parameters, the solvent activities of the polystyrene 90,000 amu+methylcyclohexane system, and the total vapor pressures of the methylcyclohexane+ethylbenzene system were calculated. The latter system was compared to experimental data, giving qualitative agreement. Figure Solvent activities for the methylcylcohexane(1)+polystyrene(2) system at 316 K. Parameters a _ij (blue line) obtained with the AM1 method; parameters a _ij (pink line) from VLE data for the ethylbenzene+methylcyclohexane system. The abscissa is the polymer weight fraction defined as ₂(x ₁)=(1–x ₁)M ₂/[x ₁ M ₁+(1–x ₁)M ₂], where x ₁ is the solvent mole fraction and M _i are the molecular weights of the components.An erratum to this article can be found at     

Exserohilum israeli, a new species isolated from soil from Timna Park (Israel), and its physiological properties

Fungi isolated from soil in Timna Park (Israel) were found to belong to a new species of Exserohilum for which the name Exserohilum israeli sp. nov. is proposed. The main physiological properties of members of this species are discussed and the influence of temperature and copper concentrations on the growth and morphology of the fungus were investigated.     

Effects of sand bar openings on some limnological variables in a hypertrophic tropical coastal lagoon of Brazil

This study describes the spatial and temporal dynamics of several physical, chemical and biological variables in the Grussai lagoon, and their relationship to ephemeral sand bar openings and to a constant in natura waste water input. The spatial variation in pH, dissolved oxygen, electrical conductivity, total alkalinity and nutrients (e.g. soluble reactive silicate, soluble reactive phosphate and ammonium) was associated to the anoxic and nutrient rich groundwater discharge, the development of aquatic macrophytes, the biological activities of phytoplanktonic community and the marine influence. During the period when the sand bar was closed (isolated), the lagoon water was supersaturated with dissolved oxygen and exhibited high values of pH (8–10), total alkalinity (3.000–5.000 μeq l^-1), and chlorophyll a contents (60-300 μg l^-1), and had low values of dissolved nutrients (nearly undetectable). These suggest a biological processes dominance. When the sand bar was opened, there was an enrichment with dissolved inorganic nutrients (e.g. ammonium and soluble reactive phosphorus up to 120 and 5 μM, respectively) and a decrease in pH (below 8), total alkalinity (below 3.000 μeq l^-1) and dissolved oxygen during the initial second to eight days. Subsequently there was a period when the physical and chemical characteristics of seawater prevailed. The lagoon returned chemical to the pre-opening water conditions in a few days (∼ 10–20). This quick return implies highly efficient biological mechanisms. The high levels of chlorophyll a, total nitrogen and phosphorus in the water column indicate a high eutrophication stage in the Grussai lagoon during the sand bar closed periods. This revised version was published online in July 2006 with corrections to the Cover Date.     

Biodeterioration of natural stone with special reference to nitrifying bacteria

An evaluation of field data from historical buildings in Germany showed that chemoorganotrophic bacteria are the most numerous microorganisms in building stones, followed by fungi and nitrifying bacteria. Chemoorganotrophic bacteria and fungi were present in almost every sample. Ammonia and nitrite oxidizers were found in 55 and 62% of the samples, respectively. Within months, natural stone was colonized by chemoorganotrophic microorganisms. The highest cell numbers were usually found near the surface. The colonization of natural stone by nitrifying bacteria took several years. The highest cell numbers were in some cases found underneath the surface. Nitrifying bacteria showed a preference for calcareous material with a medium pore radius between 1 and 10 m. Cell numbers of nitrifying bacteria did not correlate to the nitrate content of the stone material. We demonstrated that the stone inhabiting microflora can cause significant loss of nitrate by denitrification. Our data strongly suggested that microbial colonization of historical buildings was enhanced by anthropogenic air pollution. Samples taken from stone material with a pore radius 1 m had significantly higher cell numbers when they were covered with black crusts. A comparison of samples taken between 1990–1995 from buildings throughout Germany showed that in eastern Germany a significantly stronger colonization with facultatively methylotrophic bacteria and nitrifying bacteria existed. The same was true for natural stone from an urban exposure site when compared to material from a rural exposure site. Data from outdoor exposure and laboratory simulation experiments indicated that the colonization of calcareous stone by nitrifying bacteria was enhanced by chemical weathering.