Variation of vector potential in laboratory conditions changes biological properties of water

It was found that water preliminary activated with vector potential changes mobility of infusoria brought into it, the rate of sugar fermentation in yeast cells and the drinking attractivity of water for mice. It was also shown that water physical parameters changed after water activation: UV absorption spectrum and state of a silica admixture. It was supposed that water is the initial target when weak electromagnetic fields have an influence on biological objects.     

Effect of vector potential variations on monocyte/macrophage system parameters in mice in laboratory conditions

The effect of 30-min vector potential variation on the phagocytosis of macrophages from laboratory mice was investigated. It was found that the effect changes the characteristics of mice immunity: the quantity and percentage of neutrophils and lymphocytes in the blood, the activity of capture, degranulation, the splitting of bacterial agents, and the dynamics of formation of reactive oxygen species.     

Life history of the sand fly vector Lutzomyia cruciata in laboratory conditions

Lutzomyia cruciata Coquillet (Diptera: Psychodidae: Phlebotominae) is a potential vector of Leishmania sp.; its geographical distribution in Mexico is widespread, but its life history is unknown. The present study gives relevant information on the life cycle, morphology, survival and reproduction of Lu. cruciata observed over successive generations under laboratory conditions. Seven successive generations were produced. A total of 975 adults were obtained in a sexual proportion of 1.1 : 1 (female : male). Each Lu. cruciata female produced 20.7 eggs and 1.9 adults, approximately, with a proportion of eggs per female of 2.7% (first generation) and 21.3% (second generation). The life cycle of Lu. cruciata, from egg to adult, occurred in 52.7 ± 0.52 days. The largest percentage of mortality occurred during the egg stage (48.5%) and the first larval instar (26.5%), whereas in the pupal stage mortality was the lowest (9.1%). Lutzomyia cruciata exhibits sexual dimorphism based on size, which is exhibited as of the second larval instar, males being smaller than females. The maximum survival of females and males was 10 and 15 days, respectively. An overview of the immature stages of the species made with an electronic scanning microscope is included. This paper contributes basic information on aspects of Lu. cruciata that were previously unknown related to its life history.     

Parasitism-mediated prey selectivity in laboratory conditions and implications for biological control

In agroecosystems, parasitoids and predators may exert top-down regulation and predators for different reasons may avoid or give preference to parasitised prey, i.e., become an intraguild predator. The success of pest suppression with multiple natural enemies depends essentially on predator–prey dynamics and how this is affected by the interplay between predation and parasitism. We conducted a simple laboratory experiment to test whether predators distinguished parasitised prey from non-parasitised prey and to study how parasitism influenced predation. We used a host-parasitoid system, Spodoptera frugiperda and one of its generalist parasitoids, Campoletis flavicincta, and included two predators, the stinkbug Podisus nigrispinus and the earwig Euborellia annulipes. In the experiment, predators were offered a choice between non-parasitised and parasitised larvae. We observed how long it took for the predator to attack a larva, which prey was attacked first, and whether predators opted to consume the other prey after their initial attack. Our results suggest that, in general, female predators are less selective than males and predators are more likely to consume non-parasitised prey with this likelihood being directly proportional to the time taken until the first prey attack. We used statistical models to show that males opted to consume the other prey with a significantly higher probability if they attacked a parasitised larva first, while females did so with the same probability irrespective of which one they attacked first. These results highlight the importance of studies on predator–parasitoid interactions, as well as on coexistence mechanisms in agroecosystems. When parasitism mediates predator choice so that intraguild predation is avoided, natural enemy populations may be larger, thus increasing the probability of more successful biological control.     

Redox potential changes in bacterial cultures under stress conditions

Oxidation/reduction potential (ORP, redox potential, or Eh) is one of the physicochemical parameters characterizing the state of microbial cultures. Changes in pH and concentration of the redoxactive gases (O₂, H₂, and H₂S) in the cultivation medium are assumed to be the major factors of redox potential changes in the cultures of aerobic microorganisms. In the review, results of the studies of redox potential changes in various bacterial cultures under various stress conditions are summarized. The characteristic feature of these stress factors is the absence of direct correlation between the redox potential, on one hand, and partial oxygen pressure and pH, on the other. Extracellular low-molecular weight thiols (LWT) were demonstrated to be the major contributors to such changes in the redox potential. The possible role of the changes in LWT concentrations inside and outside the cells in the processes of signal transduction and redox regulation of cellular functions is discussed.     

Predawn plant water potential does not necessarily equilibrate with soil water potential under well-watered conditions

Predawn leaf water potential (O_w) and xylem pressure potential (O_p) are expected to be in equilibrium with the soil water potential (soil O_w) around roots of well-watered plants. We surveyed 21 plant species (desert, chaparral, and coastal salt marsh species, as well as two temperate tree and two crop species) for departures from this expectation and for two potential mechanisms explaining the departures. We measured soil O_w, leaf O_w, and xylem O_p in the glasshouse under well-watered conditions that eliminated soil moisture heterogeneity and ensured good soil-root hydraulic continuity. Most species failed to equilibrate fully with soil O_w, depending on whether leaf O_w or xylem O_p was used as the measure of predawn plant water potential. The contribution of nighttime transpiration to predawn disequilibrium was assessed by comparing plants with bagged canopies (enclosed overnight in plastic bags to eliminate transpiration) to plants with unbagged canopies. Nighttime transpiration significantly reduced predawn xylem O_p for 16 of 21 species and the magnitude of this contribution to predawn disequilibrium was large (0.50-0.87 MPa) in four woody species: Atriplex confertifolia, Batis maritima, Larrea tridentata, and Sarcobatus vermiculatus. The contribution of nighttime transpiration to predawn disequilibrium was not more prevalent in mesic compared with xeric or desert phreatophytic compared with non-phreatophytic species. Even with bagging that eliminated nighttime transpiration, plants did not necessarily equilibrate with soil O_w. Plant xylem O_p or leaf O_w were significantly more negative than soil O_w for 15 of 15 species where soil O_w was measured. Predawn disequilibrium based on leaf O_w was of large magnitude (0.50-2.34 MPa) for seven of those 15 species, predominately halophytes and Larrea tridentata. A portion of the discrepancy between leaf and soil O_w is consistent with the putative mechanism of high concentrations of leaf apoplastic solutes as previously modeled for a halophyte, but an additional portion remains unexplained. Predawn leaf O_w and xylem O_p may not reflect soil O_w, particularly for woody plants and halophytes, even under well-watered conditions.     

Annual changes in the copulatory behavior of male rats maintained under constant laboratory conditions

ABSTRACT

The objective of the present study was to evaluate the sexual behavior of male rats kept under constant laboratory conditions for one entire year. A total of 213 sexually-inexperienced, male Wistar rats were maintained in controlled environmental conditions from birth. Depending the month in which they reached the age 3-month-old, the male rats were divided into 12 groups, one for each month of the year, and their sexual behavior was evaluated. Records of their sexual behavior were made from 09:00 to 11:00 hrs am. The following parameters were recorded: mount (latency and number), intromission (latency and number), ejaculation latency, and intromission rate. During the months of March, June, July and September, the rats showed lower mount and intromission latencies than in January, February, April, May and October-to-December. Similarly, in March, June, July and August they had higher copulatory efficiency than in January, February, April and December. Results suggest that male rats exposed to controlled environmental conditions could have endogenous mechanisms that regulate sexual behavior but are independent of seasonal environmental signals. The annual variability in the sexual behavior of male rats maintained under constant laboratory conditions should be considered when planning research and experiments.     

Initiator and promoter induced specific changes in epidermal function and biological potential

Mouse epidermal basal cells can be selectively cultivated in medium with a calcium concentration of 0.02–0.09 mM. Terminal differentiation and slouching of mature kcratinocytes occur when the calcium concentration is increased to 1.2–1.4 mM. When basal cell cultures are exposed to chemical initiators of carcinogenesis, colonies of cells that resist calcium-induced differentiation evolve. Likewise, basal cells derived from mouse skin initiated in vivo yield foci that resist terminal differentiation. This defect in the commitment to terminal differentiation appears to be an essential change in initiated cells in skin and is also characteristic of malignant epidermal cells. This model system has also provided a means to determine if basal cells are more responsive to phorbol esters than other cells in epidermis and to explore the possibility that heterogeneity of response exists within subpopulations of basal cells. The induction of the enzyme ornithine decarboxylase (ODC) was used as a marker for responsiveness to phorbol esters. ODC induction after exposure to 12-0-tetradccanoylphorbol-13-acetate (TPA) in basal cells is enhanced 20-fold over the response of a culture population containing both differentiating and basal cells. When basal cells are induced to differentiate by increased calcium, responsiveness to TPA is lost within several hours. In basal cell cultures, two ODC responses can be distinguished. After exposure to low concentrations of TPA or to weak promoters of the phorbol ester series, ODC activity is maximal at 3 hr. With higher concentrations of TPA, the ODC maximum is at 9 hr. These results arc consistent with the presence of subpopulations of basal cells with differing sensitivities to TPA. Other studies that use the enzyme epidermal transglutaminase as a marker for differentiation support this conclusion. In basal cell culture TPA exposure rapidly increases transglutaminase activity and cornified envelope development, reflecting induced differentiation in some cells. As differentiated cells arc sloughed from the dish, the remaining basal cells proliferate and become resitant to induced differentiation by 1.2 m M calcium. These data provide additional evidence of basal cell heterogeneity in which TPA induces one subpopulation to differentiate while another is stimulated to proliferate and resists a differentiation signal. Tumor promoters, by their ability to produce heterogeneous responses with regard to terminal differentiation and proliferation, would cause redistribution of subpopulations of epidermal cells in skin. Cells that resist signals for terminal differentiation, such as initiated cell, would be expected to increase in number during remodeling. Clonal expansion of the intitiated population could result in a benign tumor with an altered program of differentiation. In skin, benign tumors are the principal product of 2-stage carcinogenesis. Subsequent progression to malignancy may involve an additional step, probably a genetic alteration, that is independent of the tumor promoter.     

Seasonal water potential changes and proline accumulation in mediterranean shrubland species

We studied the water relations of 6 shrub and 3 tree species typical of the mediterranean climate region of central Spain to identify differential responses to water stress between and within species, and to determine if free proline concentration in leaves could be used as a water stress indicator. Predawn and midday water potentials (w) on a seasonal basis, relative water content (RWC), leaf mass per area, foliar nitrogen and free proline concentrations were measured. The lowest water potentials were observed at the end of the summer, with recovery to higher water potentials in the fall and winter seasons. Species differed regarding the annual w fluctuation. Thymus zygis, Halimium viscosum, Genista hirsuta and Juniperus oxycedrus exhibited the most negative midday and predawn w (both less than -6 MPa) with a large magnitude of response to changing conditions in soil moisture of the upper horizon of the soil. Lavandula pedunculata and Cistus ladanifer showed a moderate response. Quercus rotundifolia, Quercus faginea and Retama sphaerocarpa showed a modest response. The w of different size individuals of Quercus rotundifolia and Cistus ladanifer were compared. The annual w fluctuation was greater in small individuals as compared to large individuals. In every species, there was an increase in proline concentration of bulk leaf tissues when predawn w dropped below -5 MPa. Small plants of Cistus ladanifer reached lower water potentials and also higher concentration of proline than bigger plants. Proline could possibly be used as a drought stress indicator in every species except Q. rotundifolia. It is suggested that in addition to water stress avoidance due to deep root systems, some mechanisms of water stress tolerance may operate among shrub and tree species of central Spain.     

Seasonal changes in the thermoregulation of laboratory golden hamsters during acclimation to seminatural outdoor conditions

Proper adjustments of the thermoregulatory mechanisms ensure survival in the natural environment. In the present study, we tested the hypothesis that laboratory golden hamsters (Mesocricetus auratus) housed under seminatural outdoor conditions are able to acclimatize to daily and seasonal changes in the environment despite their long history of breeding in captivity. The animals experienced natural changes in the photoperiod and ambient temperature characteristic for central Poland. During experiments in the thermal gradient system, the daily rhythms of body temperature (measured as the temperature of brown adipose tissue, TBAT), preferred ambient temperature (PTa) and activity were measured in summer, autumn and spring. We found that mean TBAT was highest in autumn and least in summer, reflecting seasonal changes in the capacity for nonshivering thermogenesis (NST). In summer, TBAT followed the robust daily rhythm with the amplitude of 1.1+/-0.1 degrees C. This amplitude was depressed in autumn (0.2+/-0.1 degrees C) and partially restored in spring (0.4+/-0.1 degrees C). Seasonal changes in the daily amplitude of TBAT recorded during both transitional periods, i.e., in autumn and spring, seem to be associated with hamsters' hibernation. In autumn, mean daily PTa was lower than in summer and spring, indicating the lowering of a set point for core body temperature (Tb) regulation. Locomotor activity was much higher in spring than in summer and autumn, and it always predominated at night. We conclude that laboratory golden hamsters housed under seminatural conditions express daily and seasonal changes in the thermoregulatory mechanisms that, despite long history of breeding in captivity, enable proper acclimatization to seasonally changing environment and ensure successful hibernation and winter survival.     

Cell cycle changes in water properties in sea urchin eggs

This study concerned changes in the motional properties of cellular water during the first cell cycle of fertilized sea urchin eggs (Lytechinus variegatus). There was a significant decrease in proton NMR T1 relaxation time and in cytoplasmic ice crystal growth during mitosis and a significant increase in T1 time and cytoplasmic ice crystal size during cleavage. This was not caused by egg water content changes as reflected by egg volume measurements. Removal of both the fertilization membrane and the hyaline layer shortly after fertilization did not alter the pattern of T1 time changes at mitosis and cleavage as compared to whole eggs; thus, the pattern of T1 time changes was attributed to intracellular events. Treatment of fertilized eggs with cytochalasin B, an inhibitor of actin polymerization, did not block the fall in T1 time at mitosis, but did block cytokinesis and the increase in T1 time, which normally occurred at cleavage. A significant pattern of actin disassembly and reassembly at mitosis and cytokinesis was found by studies on the total amount of monomeric actin (G actin) using the DNase I assay. This led to the hypothesis that the observed changes in T1 time and ice crystal size during the first cell cycle were due to the depolymerization and polymerization of cytoplasmic actin. To test this, the effect of the in vitro polymerization of purified actin on the T1 time and on ice crystal growth was examined. It was concluded that changes in the T1 time and ice crystal growth upon polymerization of actin in vitro resembled the changes seen in vivo. These results suggest that changes in the motional properties of cytoplasmic water during the first cell cycle are due, at least in part, to the state of polymerization of cytoplasmic actin.     

Diurnal changes in leaf water potential of rice,barley and wheat

The diurnal changes in leaf water potential of rice, barley and wheat corresponded to changes in air temperature. The soil moisture did not affect the diurnal changes in leaf water potential of rice and only slightly affected that of barley and wheat.     

Daily fluctuations in water potential and associated ionic changes in Atriplex canescens

Summary Water potential () measurements of Atriplex canescens at the base of the Red Desert near Tipton in Wyoming, revealed a range between-15.5 to-45.1 bars. Minimum values coincided with the lowest air and soil temperatures, maximum with the greatest atmospheric evaporative demand. Change in exceeded 12 bars h^-1 during periods of rapidly moving storm systems. Changes in appeared to be independent of plant size, age, sex, and the spatial location of plants. Chemical analyses revealed that xylem sap was up to three times more concentrated at high than at low . It was observed that the flow rate of sap was greater at lower than at higher and that the increase in water movement accounted for the dilution of the baseline concentration of sap solutes. Together, Ca, Mg, K and Na contributed 58% of the mean osmolality of the xylem sap; the dominant ions, however, were K and Cl. We suggest that the ability of the species to respond rapidly to changing atmospheric conditions affords it a distinct advantage in a harsh environment.     

不同水分管理方式对稻田土壤生物学特性的影响

在下辽河平原单季稻地区研究了常规浅湿干灌溉 (CK)、浅湿干灌溉薄膜阻渗 (IC)、湿润灌溉薄膜阻渗 (MC)、淹水灌溉薄膜阻渗 (FC) 4种不同水分管理方式下土壤线虫及土壤微生物量的动态变化。结果表明 ,耙耕前 ,CK、FC处理食细菌线虫数量显著高于MC、IC处理 ;薄膜阻渗在黄熟期显著降低了土壤食细菌线虫的数量 ,在耙耕前显著降低了食真菌线虫数量。潮棕壤稻田食真菌线虫与食细菌线虫相比数量较低。在耙耕前不同水分管理方式下土壤微生物量C显著低于对照。不同水分管理方式在水稻分蘖期、抽穗期对食细菌线虫数量、食真菌线虫数量、微生物量C和微生物量N没有影响。土壤食细菌线虫、食真菌线虫数量与土壤微生物量C、N没有达到显著相关。     

Combined changes of process conditions improved aromatic properties of Vietnamese Robusta

The flavor and taste of coffee are affected by roasting conditions and extraction temperature. This study assessed changes in the flavors and tastes of coffee extracted from Vietnamese Robusta with different roasting times and temperatures, as well as different extraction temperatures. Vietnamese Robusta green beans were roasted for different times ranging from 5 to 20 min and at different temperatures ranging from 100 to 250°C. The roasted coffee was then extracted at five different temperatures ranging from 90 to 120°C. The coffee flavor was evaluated in terms of 5 key odorants: guaiacol; 4-ethylguaiacol; 2-ethyl-3,5-dimethylpyrazine; 2,3-diethyl-5-methylpyrazine, and 2-furfuryl. The taste of coffee was evaluated in terms of 6 main compounds that confer bitterness and sourness: caffeine, trigonelline, chlorogenic acid and citric acid, acetic acid, formic acid. The optimized roasting and extracting conditions were identified that 200 g of VN Robusta green beans, roasting at 230°C for 18 min, and then extracted with Espresso Machine at 110°C.