长爪沙鼠(Meriones unguiculatus)和金黄地鼠(Mesocricetus auratus)的肺皮蒸发失水量研究

通过对长爪沙鼠和金黄地鼠肺皮蒸发失水量的研究表明,同种内个体间肺皮蒸发失水量与动物体重呈负指数相关。在10-30℃范围内,肺皮蒸发失水量随温度上升呈指数式增加。随着相对湿度的增加,肺皮蒸发失水量呈指数式减少。在10℃和20℃环境温度下,金黄地鼠肺皮蒸发失水量略高于长爪沙鼠,在30℃环境温度下,长爪沙鼠肺皮蒸发失水量略高于金黄地鼠。     

The effect of relative humidity on osmoregulation in the squirrel monkey (Saimiri sciureus)

Osmoregulatory balance was studied in four young, tamed squirrel monkeys (Saimiri sciureus, Columbia) after acclimatization to relative humidities (rh) commonly used in laboratories (30% and 50%) and to higher humidities representative of the dry and wet seasons in their natural environment (75% and 95%). The temperature was constant at 25°C and the light-dark cycle was 12:12 hours. The animals were maintained in large metabolism cages and were free moving. Water consumption and urine flow rates increased at each higher humidity from 30% rh to 75% rh and then decreased at 95% rh (p<0.05). Fecal water loss was greater with higher humidity (p<0.05). Evaporative water loss remained relatively constant until a break between 75% and 95% rh, at which point it decreased dramatically (p<0.05). Expressed relative to total water intake, evaporative water loss demonstrated a progressive decrease with increasing humidity: 65%, 56%, 51%, and 42%, at 30%, 50%, 75%, and 95% rh. This indicates that as the humidity approaches maximum saturation, not only is the evaporative water loss component necessarily diminished, but also the apparent precipitation of alternate strategies of thermoregulation leads to a reduction in the overall water requirements of the animals. Potassium/sodium excretion ratios were relatively constant at 30%, 50%, and 95% rh but decreased significantly at 75% rh (p<0.05). As a reflection of adrenocorticosteroid activity, this suggests that at 25°C, 75% rh is an optimal humidity in the maintenance of squirrel monkeys. The significant osmoregulatory alteration occurring between 75% and 95% rh provides further evidence that relative humidity may be an important factor in the seasonal physiological cycles of the squirrel monkey. In conducting the research described in this report the investigators adhered to the “Guide for Laboratory Animal Facilities and Care,” as promulgated by the Committee on the Guide for Laboratory Animal National Academy of Sciences, National Research Council.     

Survival of Botrytis cinerea in Soil in South-Eastern Spain

The survival of Botrytis cinerea in sterile and unsterile soil at different temperatures and relative air humidities was investigated in south‐eastern Spain. Conidia survived only 7 days at 40^°C but, depending on relative humidity, for 30–90 days at 22^°C. High air humidity (95%) was needed to maintain soil humidity (8%) at a level that favoured conidial survival. Conidia survived better in sterile soil than in unsterile soil, probably because of the presence in the latter of soil microorganisms antagonistic to B. cinerea. Survival of conidia in environmental conditions simulating those in a greenhouse was less than 28 days. Results showed that B. cinerea conidia cannot survive over summer in south‐eastern Spain, and other primary sources of inocula are discussed.     

Post-secretory determinants of sugar concentration in nectar

Abstract. The concentration of sugar in the nectars of unprotected flowers of several species was measured and did not reach the high values that would be in equilibrium with the daytime humidities recorded outside the corolla, although the sugar concentration was highly correlated with ambient relative humidity. This paper examines features that maintain low nectar sugar concentrations at low ambient humidities. Post-secretory changes in concentration are influenced to a small extent by nectar composition but depend largely on physico-chemical and microclimatic effects. Factors contributing to the maintenance of steep gradients in water activity between the nectar and the ambient air include corolla morphology, sugar concentration gradients and waterproofing lipid monolayers on the nectar surface. This paper considers the relative importance of such features in relation to the pollination syndrome. A simple technique is described for the measurement of intrafloral relative humidity.     

Effect of air humidity on the development of functional stomatal apparatus

Phaseolus vulgaris L. seedlings were grown under different air humidities simulating conditions during micropropagation (very high humidity duringin vitro cultivation and low air humidity after transferex vitro). The functional stomatal apparatus developed after a short period of growth at low air humidity at the beginning of plant ontogeny or after transfer from high to low air humidity, but not in plants grown steadily under high air humidity. The ability of stomata to regulate gas exchange was not persistent and disappeared after transfer of plants from low to high humidity. The author thanks Mrs. L. Kolčabová for her skilled assistance. The paper is a part of the project supported by the grant No. 501/95/1303 of the Grant Agency of the Czech Republic.     

Effects of relative humidity on development, fecundity and survival of three storage mites

The developmental rate of immature stages and the reproduction of adults of Tyrophagus putrescentiae (Schrank), T. neiswanderi Johnston and Bruce and Acarus farris (Oudemans) were examined at 70, 80 and 90% r.h. and a constant temperature of 25°C. At 70% r.h., T. putrescentiae and A. farris immature stages failed to reach the protonymph stage as 100% of the larvae died, whereas T. neiswanderi was able to complete development. The developmental time of all immature stages for the three species was significantly increased as relative humidity was reduced. The mobile stages were particularly susceptible, as the time needed to complete their development at lower relative humidities suffered greater increases than the egg stage. At 70% r.h., T. putrescentiae and A. farris were not able to lay eggs and only 24% of T. neiswanderi pairs were fertile. The reproductive parameters of the three species at the relative humidities at which they were able to lay eggs showed significant differences, except for the percentage of fertile mating at 80 and 90% r.h. As relative humidity increased, preoviposition period was reduced and fecundity and daily fecundity was increased, whereas the oviposition period showed different patterns for the three species. The intrinsic rate of increase (r _m ) of T. neiswanderi at 70% r.h. was negative indicating that, at these conditions, mite populations of this species will diminish until they disappear. As relative humidity increased from 80 to 90% r.h. this parameter was almost twofold for both Tyrophagus species. The r _m obtained for A. farris at 90% r.h. was similar to that of T. neiswanderi at the same humidity while at 80% r.h. it was very small so that the population doubling time was more than 84 days. The influence of relative humidity on biology of these mites and its practical application as control measure are discussed.     

Temperature-dependent dry receptor on antenna ofPeriplaneta. Tonic response

Summary Identified as a dry receptive unit by transitory impulse frequencies up to about 200 imp/sec during rapid drops in humidity (Fig. 3) and which no other modality elicited, the dry unit on the antenna ofPeriplaneta americana is characterized by a regular (Fig. 4) and relatively high stationary impulse frequency (10–65 imp/s). Without exception the stationary discharge rate (tonic frequency) rose with falling values of stationary absolute humidity at constant temperature, and with rising values of stationary temperature of ambient air at constant humidity. Enthalpy and evaporation cooling appear to be ruled out as exclusive adequate explanations for this double dependence. No matter whether tonic frequency is plotted against absolute humidity based on either volume of moist air or weight of dry air, or against partial pressure of water vapor in ambient air, or the difference between saturation and partial vapor pressure, or against relative humidity, the dependence on the temperature is not eliminated (Figs. 5–7). Because a temperature range of about 20 °C and all humidities between 0 and 100% occupy the same large segment of the unit's tonic frequency spectrum (Fig. 8), the unit is termed bimodal.The author wishes to express indebtedness and gratitude to Prof. Dr. Hansjochem Autrum for backing the early stages of this project with the assistance of the Deutsche Forschungsgemeinschaft, to Prof. Dr. Helmut Altner for his prolonged support, to Dr. Hans-Jürgen Hinz for his helpful discussion of questions involving thermodynamics, to Prof. Dr. Friedrich Earth for helpful criticism of the text, and to Miss Christel Praeg for tireless technical assistance.     

Effect of different eriophyid and tetranychid mango mite species on development,longevity, fecundity and predation of Typhlodromus mangiferus Zaher and El-Brolossy (Acari: Phytoseiidae)

Effects on development, longevity, fecundity and predation of the predatory phytoseiid mite Typhlodromus mangiferus Zaher and El-Brolossy were studied in the laboratory at different temperatures and relative humidities using four prey mite species: the motile stages of the eriophyid mango bud mite Aceria mangiferae Sayed, the eriophyid leaf coating and webbing mite Cisaberoptus kenyae Keifer, the eriophyid mango rust mite Metaculus mangiferae (Attiah) and nymphs of the tetranychid mango red mite Oligonychus mangiferus (Rahman and Sabra). The increase of different temperatures and decrease of relative humidities from 25°C and 60% to 30°C and 55% and 35°C and 50% shortened development and increased reproduction and prey consumption. The developmental durations were almost similar when the predator was fed on eriophyids compared to that on tetranychid. The maximum reproduction (2.70, 2.08, 1.97 and 1.66 eggs/ ♀ /day) was recorded at the highest temperature and the lowest relative humidity, while the minimum reproduction (1.7, 1.54, 1.53, and 1.06 eggs/ ♀ /day) was noted at the lowest temperature and highest relative humidity with all mango prey species. Life table parameters indicated that feeding of T. mangiferus on A. mangiferae led to the highest reproduction rate (rm = 0.204 and 0.139 females/female/day), while feeding on O. mangiferus gave the lowest reproduction rate (rm = 0.137 and 0.116) at 35°C and 50% relative humidity and 25°C and 60% relative humidity, respectively. T. mangiferus seems to be a voracious predator of both mango eriophyid and tetranychid mites. The adult female daily consumed about 127 A. mangiferae, 97 C. kenyae, 86 M. mangiferae, and 18 O. mangiferus at 35°C and 50% relative humidity, while it devoured only 99.81, 86, 81, and 15 individuals, respectively at 25°C and 60% relative humidity. The present study revealed that each injurious mite is thought to be profitable prey species to T. mangiferus as a facultative predator.     

Aeroterrestrial Microalgae Growing in Biofilms on Facades—Response to Temperature and Water Stress

The photosynthetic performance of a microalgal biofilm colonizing a building facade was investigated between February and July 2004, with an emphasis on changing water availability and air humidity. The fluorimetric measurements of the quantum efficiency (F _v/F _m) indicated diurnal activity patterns. At most sampling dates the algal biofilm photosynthesized particularly in the morning and substantially less in the afternoon. As long as liquid water was present, the microalgae exhibited at least some degree of photosynthesis. However, F _v/F _m values never exceeded 0.4, pointing to slight photoinhibition or damage of the cells. Dried cells without photosynthesis could recover within minutes after artificial moistening.Three microalgal strains were isolated from aeroterrestrial biofilms and established as unialgal cultures. Their photosynthesis and growth were characterized under different air humidities and temperatures. Photosynthesis and growth of strain ROS 55/3 (Stichococcus sp.) showed similar patterns with decreasing relative air humidity. Positive growth and optimum photosynthesis were recorded at 100% relative air humidity. At air humidities below 93%, both processes were strongly inhibited. All studied strains grew between 1 and 30°C with optimum rates at 20–23°C, indicating eurythermal features.The data indicate that liquid water or 100% air humidity are the prerequisite for optimum photosynthesis and growth of aeroterrestrial microalgae. However, when dried and consequently inactive, these microorganisms can recover quickly if water is suddenly available, e.g., after rain events. These physiological capabilities explain well the ecological success of aeroterrestrial microalgae in occupying many man-made substrata such as building facades and roof tiles in urban areas.     

Effect of humidity on the stability of lung surfactant films adsorbed at air-water interfaces

The effect of humidity on the film stability of Bovine Lipid Extract Surfactant (BLES) is studied using the captive bubble method. It is found that adsorbed BLES films show distinctly different stability patterns at two extreme relative humidities (RHs), i.e., bubbles formed by ambient air and by air prehumidified to 100% RH at 37 °C. The differences are illustrated by the ability to maintain low surface tensions at various compression ratios, the behavior of bubble clicks, and film compressibility. These results suggest that 100% RH at 37 °C tends to destabilize the BLES films. In turn, the experimental results indicate that the rapidly adsorbed BLES film on a captive bubble presents a barrier to water transport that retards full humidification of the bubble when ambient air is used for bubble formation. These findings necessitate careful evaluation and maintenance of environmental humidity for all in vitro assessment of lung surfactants. It is also found that the stability of adsorbed bovine natural lung surfactant (NLS) films is not as sensitive as BLES films to high humidity. This may indicate a physiological function of SP-A and/or cholesterol, which are absent in BLES, in maintaining the extraordinary film stability in vivo.     

Effect of relative humidity of hot air on the heat resistance of Bacillus cereus spores

The heat resistance to hot air of spores of Bacillus cereus (ATCC 14579) attached to carriers of stainless steel or silicone rubber was investigated in a range from 1% to 100% relative humidity (RH). Apart from an initial stage, linear survivor curves were obtained for all relative humidities. Neither the attachment itself nor the material of the carrier had an influence on the resistance. A distinct maximum of heat resistance was found at 40% RH. At 122°C the rate constants at 40% RH were five orders of magnitude smaller than at 100% RH and two orders of magnitude smaller than at 1% RH. At relative humidities of more than 40% the rate constants were strongly temperature dependent, whereas at lower relative humidities they were less temperature dependent. No significant influence of the relative humidity on the Arrhenius activation energy was found within each humidity range. The mean values were 295 kJ mol^-1 for relative humidities of 60% to 100% RH and 165 kJ mol^-1 for 1% to 20% RH. The occurrence of a maximum is ascribed to the existence of two inactivation mechanisms, the first is retarded and the second is accelerated by a reduction of relative humidity. It is assumed that the first mechanism is a protein denaturation. The second mechanism may be an oxidative process.     

Environmental conditions and their impact on immunocompetence and pathogen susceptibility of the Caribbean termite Nasutitermes acajutlae

1. Little is known about interactions between environmental conditions surrounding insects and their immune responses. 2. The environment in and around termite colonies, including temperature, relative humidity, soil pH, and light was analysed using principal components analysis (PCA). 3. The relationship between these abiotic parameters and two aspects of termite immunity (phenoloxidase activity and lipid content) was examined in field‐caught workers of Nasutitermes acajutlae Holmgren. Finally, termites from warm/dry and cool/moist habitats were exposed to Metarhizium anisopliae to determine their susceptibility to mycosis. 4. PCA indicated that environmental components external to the nest [ambient temperature, ambient relative humidity (RH), soil temperature and light] comprised the majority (PC1 = 37.5%) of variation. Internal variables (nest temperature and RH) and nest volume accounted for 19.6% (PC2) of the variation with pH comprising 12.9% (PC3). 5. AIC and regression models suggested that ambient temperature was most strongly and positively associated with immune variables and that relative humidity may also play a role. Termites from warm/dry colonies were less susceptible to M. anisopliae than termites from cool/moist colonies. 6. Thus, termites nesting in warmer habitats may exhibit increased immune‐related measures and reduced susceptibility to mycosis compared with termites from cooler habitats.     

Comparison of the behavioural and physiological responses to humidity of five species of dry-wood termites, Cryptotermes species

ABSTRACT. A circular humidity gradient apparatus with a porous cellulose substrate was used to compare the humidity responses of pseudoworkers (immature wood-feeding forms) of five species of dry-wood termites. Four of these species are widely distributed pests of buildings: Cryptotermes brevis (Walker), C. cynocephalus Light, C. dudleyi Banks and C. havilandi (Sjöstedt). The fifth species, C. naudei Coaton, has not been recorded from buildings. C. havilandi, C. cynocephalus and C. naudei were found to tend to group and feed at humidites above 90% r.h., while C. dudleyi pseudoworkers avoided humidities above 90% r.h. and below 70% r.h. These results accord with the results of studies on the effects of relative humidity on feeding and reproduction of these species. The behaviour of the most widespread species, C. brevis , seems to be closely associated with its ability to undergo acclimatization and to feed efficiently at either medium ( c. 60%) or high ( c. 90%) relative humidity. C. brevis kept at 89% r.h. showed an increased tendency to group at humidities above 90%, with a lower temperature preference, changes in faecal pellet formation and, for one population at least, an increased tolerance of exposure to saturated air. The humidity preferences at constant temperature were compared with the temperature preferences of the same individuals examined in uniform humidity. The value of behavioural responses as indicators of physiological differences between species and populations is considered.     

Water vapour uptake from the atmosphere and critical equilibrium humidity of a feather mite

The feather miteProctophyllodes troncatus Robin takes up water vapour from subsaturated atmospheres down to relative humidities between 55% and 60%. Vapour uptake increases with rising humidity of the surrounding air and the time to attain maximum water gain decreases.     

Effect of humidity on the stability of lung surfactant films adsorbed at air-water interfaces

The effect of humidity on the film stability of Bovine Lipid Extract Surfactant (BLES) is studied using the captive bubble method. It is found that adsorbed BLES films show distinctly different stability patterns at two extreme relative humidities (RHs), i.e., bubbles formed by ambient air and by air prehumidified to 100% RH at 37 degrees C. The differences are illustrated by the ability to maintain low surface tensions at various compression ratios, the behavior of bubble clicks, and film compressibility. These results suggest that 100% RH at 37 degrees C tends to destabilize the BLES films. In turn, the experimental results indicate that the rapidly adsorbed BLES film on a captive bubble presents a barrier to water transport that retards full humidification of the bubble when ambient air is used for bubble formation. These findings necessitate careful evaluation and maintenance of environmental humidity for all in vitro assessment of lung surfactants. It is also found that the stability of adsorbed bovine natural lung surfactant (NLS) films is not as sensitive as BLES films to high humidity. This may indicate a physiological function of SP-A and/or cholesterol, which are absent in BLES, in maintaining the extraordinary film stability in vivo.     

The role of spider cocoons in controlling desiccation

Summary The abilities of the cocoons of the spiders Mecynogea lemniscata and Argiope aurantia to protect the enclosed egg and spiderling stages from desiccation were investigated in the laboratory under controlled humidities, and in the field under ambient conditions. For M. lemniscata, which has a relatively small clutch (8–30 eggs) and remains in the cocoon for approximately 9–10 months, removal of the cocoon had no effect on water loss from the egg stage, nor did it adversely affect hatching or molting success. Cocoon removal did, however, significantly affect water loss and, consequently, survival in the spiderling stage at all humidities in the laboratory and in the field. The importance of the cocoon for survival is probably related to the unusually long time M. lemniscata spiderlings spend in the cocoon overwintering. For A. aurantia, which has a substantially larger clutch size (300–1400 eggs) and remains in the cocoon for a shorter 6–7 months, cocoon removal had no effect on water loss, egg hatching success, molting success, nor spiderling survival. The lack of an effect suggests that other factors (e.g., relative humidity at the oviposition site, or a large clutch size) may be more important in controlling water loss for A. aurantia.     

The influence of humidity on emergence in Dacnusa sibirica Telenga (Hymenoptera: Braconidae)

The effects of four humidities (33, 55, 76 and 93% relative humidity) and four ages (0–1, 2–3, 4–5, 6–7 days) of parasitized Chromatomyia syngenesiae puparia on adult emergence in the leafminer parasitoid Dacnusa sibirica were examined in the laboratory. Parasitized puparia harvested at 0–1 days were susceptible to low humidities resulting in a significantly reduced parasitoid emergence. Aging of the puparia appeared to protect the developing parasitoid from low humidities. Increasing humidity produced a corresponding increase in the longevity of the adult parasitoid.     

Water potential, turgor and cell wall properties in elongating tissues of the hydrotropically bending roots of pea (Pisum sativum L.)

The hydrotropic bending of roots of an ageotropic pea mutant, ageotropum, was studied in humid air in a chamber with a steady humidity gradient. We examined the effects of atmospheric humidity around the root on the water status of root tissues, as well as the wall growth and the hydraulic properties of the elongating tissues. Atmospheric humidity at the surface of the root was clearly lower on the side orientated towards the air with lower humidity than on the side orientated towards the air with higher humidity. However, there were no differences in water potential and osmotic potential between the tissues that faced air with higher and lower humidities in the elongating and mature regions. Plastic extensibility was higher in the tissues that faced the air with lower humidity than in the tissues that faced the air with higher humidity. No differences in turgor pressure and yield threshold were observed between the tissues that faced air with higher and lower humidities. Therefore, the extensibility of the cell wall appeared to be responsible for the different growth rates of tissues in root hydrotropism. A further probable cause of the hydrotropical bending of roots is changes in the hydraulic conductance in the elongating tissues. Since the hydrotropic bending of roots occurred only when a root tip was exposed to a humidity gradient, hydrotropism might occur after perception of a difference in humidity by the root tip, with accompanying changes in cell wall extensibility and hydraulic conductance.     

Hygroreception in olfactometer studies

Abstract In olfactometric studies, a technique used to measure insect behavioural bias towards airborne chemicals, many of the factors that could affect the bioassay outcome other than the volatiles themselves are carefully controlled (e.g. lighting conditions, temperature, spatial position, physiological state of the insects, time of day when the bioassay is performed) but one factor, namely humidity, is overlooked frequently when studying responses to plant volatiles. Many insect species respond positively and negatively to changes in humidity and, during bioassays, differences arising from odour choices with different water vapour release rates might have confounding effects versus the original intent of the behavioural study. The present study aims to assess the effect of different substrates on the water vapour content of air in an olfactometer‐like set‐up. The results show that airflow humidity is affected by the odour source used in the olfactometer air flow. In addition, the response of the aphid parasitoid Aphidius colemani Viereck (Hymenoptera: Aphidiidae) is studied towards different humidities and plant material in an olfactometer. The present study suggests that humidity needs to be controlled in olfactometric studies.     

Effect of abscisic acid, osmolarity and partial desiccation on the development of recalcitrant mango somatic embryos

Inhibition of mango somatic embryo growth was inducedin vitro by treatments for 4 or more weeks with abscisic acid (0–100 M ABA) with and without high osmolarity provided by mannitol (0–10%). High osmolarity and ABA significantly affected somatic embryo length, precocious germination and the production of good quality secondary somatic embryos. High osmolarity also affected root elongation. Abscisic acid was more effective in suppressing growth and development of 0.5 cm-length somatic embryos than smaller somatic embryos. Development beyond the heart stage was significantly inhibited by both ABA and mannitol treatments. The recovery of good quality somatic embryos was enhanced by high levels of ABA (100 M) with and without mannitol (0–5%). Somatic embryos that had been pulsed with ABA were partially desiccated at different relative humidities. Weight loss was affected only by relative humidity; and ABA did not enhance desiccation tolerance.Abbreviations ABA Abscisic acid - 2,4-D 2,4-Dichlorophenoxyacetic acid - MM1 Mango maturation medium - RH Relative humidity