Larval case and water balance in Tinea pellionella

In a very dry environment (0% r.h.) the case plays an important role in the physiology of the Tinea pellionella larva. Absence of the case leads to a reduction of oxygen consumption and a great loss of body water. At 0% r.h. the rate of water loss from a larva without its case, is twice that from a larva remaining within its case.In a very humid environment (r.h. higher than 95%) the case absorbs a very large quantity of water and becomes very heavy, but it does not interfere with larval physiology. With or without their cases the weight of the larvae stays stable, and their oxygen consumption does not change.When the humidity changes abruptly, the case acts as a buffer and assists in the regulation of the water balance of the larva. If the humidity decreases the case slows the rate of body water loss; if the humidity increases, it very quickly builds up a reserve of atmospheric water around the larva's body.     

Influence of Aloe vera on water absorption and enzymatic in vitro degradation of alginate hydrogel films

This study investigates the influence of Aloe vera on water absorption and the in vitro degradation rate of Aloe vera-Ca-alginate hydrogel films, for wound healing and drug delivery applications. The influence of A. vera content (5%, 15% and 25%, v/v) on water absorption was evaluated by the incubation of the films into a 0.1 M HCl solution (pH 1.0), acetate buffer (pH 5.5) and simulated body fluid solution (pH 7.4) during 24 h. Results show that the water absorption is significantly higher for films containing high A. vera contents (15% and 25%), while no significant differences are observed between the alginate neat film and the film with 5% of A. vera. The in vitro enzymatic degradation tests indicate that an increase in the A. vera content significantly enhances the degradation rate of the films. Control films, incubated in a simulated body fluid solution without enzymes, are resistant to the hydrolytic degradation, exhibiting reduced weight loss and maintaining its structural integrity. Results also show that the water absorption and the in vitro degradation rate of the films can be tailored by changing the A. vera content.     

影响蝴蝶兰类原球茎耐脱水性的主要因素

为探讨蝴蝶兰(Phalaenopsis spp.)类原球茎(protocorm-like body,PLB)耐脱水性的主要影响因素,对PLB的平均粒重、含水率、脱水相对湿度、时间、温度、光周期与耐脱水性的关系进行了研究.结果表明,PLB的平均粒重与脱水后失水率、含水率、相对电导率、成活率呈显著或极显著相关.在较高湿度下...     

VORZUGSTEMPERATUR UND VORZUGSLUFTFEUCHTIGKEIT DER BEIDEN SCHABENARTEN PERIPLANET A AMERICANA UND BLABERUS TRAPEZOIDEUS (INSECTA: BLATTARIA)

Von adulten Männchen der beiden Schabenarten Periplaneta americana und Blaberus trapezoideus wurden gleichzeitig Vorzugstemperatur und Vorzugsluftfeuchtigkeit ermittelt. Für beide Arten konnten in ihren Vorzugstemperaturen gewisse Akklimatisationserscheinungen festgestellt werden. Bei P. americana steigt die Vorzugstemperatur von 26°–29° nach einem einmonatigen Aufenthalt bei 20° auf etwa 29°— 30° nach einerer Exposition bei 35° an. B. trapezoideus hat eine um etwa 3° niedrigere Vorzugstemperatur. Nach einem Aufenthalt bei 20° beträgt sie etwa 23°–26°. Sie steigt auf etwa 26° nach einer Exposition bei 32° an. P. americana bevorzugt stets ein trockenes Milieu (geboten wurden 18% r.L.), B. trapezoideus sucht höhere Luftfeuchtigkeit auf (45%–93% r.L.) und meidet trockenes Milieu. Ein Gewichtsverlust von 15%–18% veranlaßt P. americana eine um 1°–3° niedrigere Vorzugstemperatur, aber vor allem eine sehr hohe Luftfeuchte aufzusuchen. Ein Gewichtsverlust von 20%–25% des Körpergewichtes hat keinen Einfluß auf die Vorzugstemperatur von B. trapezoideus; jedoch halten sich die Tiere nur ebenfalls länger in sehr hoher Luftfeuchte auf.     

Studies on the relationship of water balance properties and survival in the Hawaiian drosophilid, D. Mimica

Some aspects of the relationship between water balance characteristics and biological fitness have been explored both for a laboratory-reared stock (K85P1) of Drosophila mimica and for each of four field-caught populations of D. mimica. At low a_v's, there is a clear correlation between water loss rates and survival time, but at saturation, the relationship is less striking. Neither body weight nor sex correlate strongly with water loss rate at 0.70 a_v, but females survive longer than males. Some differences in the response to desiccation between populations from different collection sites are also suggested.     

Culture of fat body of Periplaneta americana: Tissue development and establishment of cell lines

Long-term culture of larval fat body from Periplaneta americana was carried out. The cultures in a chemically defined medium show a strict dependance of the fat body on oxygen. The cultures with serum supplementation give rise to numerous cell migrations. We have studied the development of the different cell types and especially that of the mycetocytes and adipocytes. The mycetocytes can be cultured provided that they remain associated with the adipocytes. In these mycetocytes, the progressive loss of the symbiotes is related to the lipid load. The adipocytes continue to store lipids and glycogen for over 6 months. Then, the selection of different phenotypes gives rise to a homogeneous and adipocyte-like cell population. After 7 months, these cells can be subcultured regularly and a new cell line from P. americana has been established which is the only one isolated from explants of the insect fat body.     

Water-deficit Stress, Ethylene Production, and Ripening in Avocado Fruits

Differential rates of water loss were achieved in picked avocado (Persea americana Mill.) fruits, either by controlling the evaporation rate or by supplying water through the fruit stalk. A negative linear correlation was found between the daily rate of water loss from fruits and their ripening, as determined by the time from harvest to peak of ethylene production. Ripening rate was hastened by 40% in fruits which had lost water at rate of 2.9% fresh weight per day, compared with those which lost only 0.5% per day.     

Effects of temperature and humidity on hydration and respiration in four strains of Drosophila

The four strains of Drosophila melanica studied were found to be most sensitive to low humidities during the first 19 hr after formation of the puparium. The mean fresh weights for the four strains were consistently different at all ages after puparium formation and at all conditions of temperature and humidity. The Forest Park strain, which showed greatest mortality at low humidity, had least body water per unit dry weight in the early pupal stage.A typical U-shaped oxygen consumption rate curve was found during the puparial-pharate adult period at all conditions of temperature and humidity. Differences among the strains were manifested at an earlier age under the more extreme environmental conditions.     

Physiological energetics of the green abalone, Haliotis fulgens, fed on a balanced diet

A regression of different physiological responses against body size enables populations or stock cultures of various size ranges to be compared. Thus, the aim of the present work was to evaluate the physiological responses from juvenile green abalone (Haliotis fulgens), grouped according to size, in a standard controlled culture condition within their optimal range to create the balanced growth equation within an allometric relation, providing a basic framework for physiological research into H. fulgens. Feed intake, absorption efficiency, respiration and excretion were measured as functions of dry tissue weight (DTW) in juvenile abalone acclimated on a balanced diet. The daily feed intake (I) was related to body mass by the relationship I (mg day⁻¹)=24.25W^0.59. Absorption efficiency averaged 87% and was independent of body size. The equation relating daily respiration rate (R) to body mass was R (ml O₂ day⁻¹)=12.013W^0.704, including night correction. The rate of ammonia excretion (U) was related to dry tissue weight by the equation U (μmol N-NH₄ day⁻¹)=43.57W^0.85. The energetic value of food was 18.8 J mg⁻¹. The low feeding activity (<1% of abalone live weight per day) was compensated for by a relatively high absorption efficiency and a depression of 23% in the metabolic rate during diurnal activity. Gross and net growth efficiencies were constant throughout the size range, with average values of 36.4% and 41.5%, respectively. Values of the O/N ratio, with an average of 31.5, showed a higher use of proteins from the diet as an energy source for the size range studied.     

Blood volume and total water content of the woodlouse, Oniscus asellus, in conditions of hydration and desiccation

Changes in the blood volume and total water content of Oniscus asellus were measured by means of inulin dilution and weight. The relationship between body weight and blood volume, total water content, and weight loss does not change during desiccation. The process of desiccation is similar in 0% r.h. and 62% r.h., although the rates of reduction of blood volume, total water content and weight are different in these two humidities. During desiccation most of the water lost by the animal comes from the blood. There is no evidence to suggest that O. asellus takes up an excess of water in moist conditions.     

Flight fuels in the brown planthopper Nilaparvata lugens

The flight fuels of Nilaparvata are a combination of carbohydrate and lipid. In insects of constant age, lipid deposits are proportional to body weight, as is the rate of utilisation of lipid in flight. Reserves of glycogen are more variable and show no correlation with body weight. They are also always extremely low, approximately 0.2% of the live weight, in flight-willing insects. During flight there is evidence that, unlike other migrant insects, carbohydrate metabolism may continue for some hours and some lipid utilisation may begin almost immediately flight is initiated.     

Isolation of proctolin,a myotropic peptide,from Periplaneta americana

The isolation of a myotropic substance, proctolin, associated with the innervation of the viscera of the cockroach, Periplaneta americana, is reported. Proctolin, previously described as a neurotransmitter or neurohormone, is a small basic peptide with an estimated molecular weight of 500 to 700. The proctodeal (hindgut) muscles of P. americana contract at threshold levels of about 0·5 ng/ml, equivalent to about 10⁻⁹ M proctolin. Approximately 180 μg proctolin were isolated from 125 kg of whole cockroaches. The isolated peptide was homogeneous on paper and thin-layer chromatography and on high-voltage paper electrophoresis at pH 3·5 and 6·4.     

Occurrence,properties and biological implications of the active uptake of water vapour from the atmosphere in Psocoptera

Water vapour absorption is shown to occur in 22 species of Psocoptera inhabiting diverse environments and representing all major groups of this insect order. Evidently the faculty is a common feature of the whole order and it seems not to be related to specific environmental conditions. For the first time water vapour uptake could be demonstrated in fully winged and flying insects. The critical equilibrium humidities vary considerably among different species ranging from 58 to 85% r.h. Marked interspecific differences are also observed in water loss and uptake rates but no clear correlation with habitat or systematic group is recognizable. The uptake rates of Psocoptera are among the highest of all arthropods investigated so far. From weight recordings with a sensitive microbalance it could be seen that continuous operation of the uptake mechanism is restricted to limited periods of time of less than 1 hr regardless of the water status of the animals. Initiation and termination of the uptake process are abrupt and continuous uptake proceeds at a constant rate at a given relative humidity. Uptake rates are humidity-dependent decreasing with falling relative humidity whereas the adjustment of the equilibrium level of body water is independent of ambient humidity. Equilibrium is maintained by intermittent operation of the uptake mechanism within ca. 3% of body water mass. The uptake mechanism exhibits marked sensitivity to starvation in most members of the Psocomorpha. Some features of the uptake process of Psocoptera are in close agreement with those of Mallophaga reflecting the close relationship between the two groups.     

The biomass and nutritive potential of Vallisneria americana Michx in navigation pool 9 of the upper Mississippi river

Vallisneria americana Michx (wild celery) was studied to determine the biomass and nutritive potential of all morphological structures. A 2.6-ha stand of uniform V. americana was sampled during the summer and autumn of 1980, and the spring and summer of 1981 in the southern portion of Navigation Pool 9 of the Upper Mississippi River.The maximum production rate of 3.2 g m^?2 day^?1 was coincident with rapid rosette production and flowering, and occurred mid- to late-July 1980. The maximum biomass of 217.3 g dry wt. m^?2 was on 1 September 1980, when fruit development was also at a maximum. Leaves composed 60–70% of the summer biomass; winter buds constituted all of the winter biomass.Winter buds and fruits had the greatest nutritive potentials. Both organs contained relatively high dry matter concentrations and were low in ash (less than 10%) and fiber content. The potentially-digestible ash-free non-cell-wall fraction (NCF) was composed of an average of 75.7 and 82.2% of the dry weight of fruits and winter buds, respectively. In contrast, the nutritive potential of leaves, rootstocks, peduncles and stolons was reduced because of high moisture (less than 8% dry matter), ash and fiber concentrations. Staminate inflorescences and pistillate flowers were high in crude protein (averaged 21.8% and 16.1% of the dry-weight, respectively) and ash-free non-cell-wall fractions, but they accounted for only 2.7% of the plant biomass. The maximum calorific content of V. americana was approximately 3200 kJ m^?2 at peak biomass on 1 September 1980.     

[树]麻雀羽再生的能量预算和水代谢散热调节

为探讨[树]麻雀的羽再生能力、能量预算对策和有效的散热调节方式,对3组(对照CF、去飞羽FF和去尾羽组TF)[树]麻雀(Passer montanus)进行4周驯养(Acclimation)。结果发现:[树]麻雀具有较强的羽再生能力和飞羽参与个体保温。羽再生[树]麻雀能量收支水平降低极显著(P﹤0.001),FF组和TF组比CF组减少依次为:摄入能19.77%和7.17%、消化能18.79%和6.47%、同化能18.73%和6.46%、粪能28.66%和13.35%、水代谢散热热能26.95%和7.43%、排泄次数33.71%和14.40%,增加依次为:消化率1.23%和0.78%、同化率1.35%和0.84%。个体能值水平,体重CF、TF和FF组(P﹤0.05)依次降低,体温组间变化不显著(P﹥0.05)。体内能量储备,血糖、肌糖原、体脂和水分含量组间差异不显著(P﹥0.05),肝糖原含量、体脂重组间差异显著(P﹤0.05)。器官水平包括心脏、肾脏、腺胃、小肠、盲肠和总消化道长度及质量出现积极的响应。日代谢水量组间差异极显著(P﹤0.001)。组间日排泄次数最少平均为56.11次和最多可达96.34次/只。结果表明:羽再生[树]麻雀分别选择了不同程度的降低能量收支水平,提高摄入食物的消化、吸收效率,动用体内能量储备来获取摄入能量不足部分,降低器官总能耗的能量预算对策和不同的新羽(再生羽枚数:飞羽部分和尾羽全部)再生的能量投资对策。泄殖腔排出(粪尿混合物)水是鸟类特有的、迅速的和有效的散热调节方式。     

空气湿度与土壤水分胁迫对紫花苜蓿叶表皮蜡质特性的影响

选用2个抗旱性不同的紫花苜蓿品种,敖汉(强抗旱)和三得利(弱抗旱),设置空气湿度(45%-55%和75%-85%)和土壤水分胁迫(75%和35%田间持水量)处理,分析紫花苜蓿叶表皮蜡质含量、组分及晶体结构、气体交换参数、水势及脯氨酸含量的变化规律。结果表明,单独土壤水分胁迫时,紫花苜蓿叶表皮蜡质晶体结构及蜡质总量无显著变化;敖汉蜡质组分中烷类、酯类含量增加,醇类含量下降;三得利醇类含量下降,烷类、酯类含量变化不显著。低空气湿度胁迫时,两品种蜡质总量无显著变化,烷类和酯类含量显著增加,醇类含量显著下降,叶表皮片状蜡质晶体结构熔融呈弥漫性,扩大了对叶表面积的覆盖,其蒸腾速率显著低于正常湿度。复合胁迫处理时,叶表皮片状蜡质晶体结构继续呈弥漫性,烷类、酯类、未知蜡质组分含量均高于单独胁迫处理,醇类含量最低,而蜡质总量除三得利显著高于对照外,其余均无显著差异。紫花苜蓿叶表皮蜡质各组分含量(除醇类)及蜡质总量与光合速率呈显著负相关,与蒸腾速率无显著相关关系。蜡质总量与叶水势呈显著正相关。总体上,敖汉蜡质总量显著高于三得利,蜡质组分中烷类物质的增加有助于提高植株的抗旱性。在复合胁迫下,强抗旱品种主要通过气孔因素控制水分散失,而弱抗旱品种通过气孔和非气孔因素共同控制植物水分散失。     

Responses of epidermal cell turgor pressure and photosynthetic activity of leaves of the atmospheric epiphyte Tillandsia usneoides (Bromeliaceae) after exposure to high humidity

It has been well-established that many epiphytic bromeliads of the atmospheric-type morphology, i.e., with leaf surfaces completely covered by large, overlapping, multicellular trichomes, are capable of absorbing water vapor from the atmosphere when air humidity increases. It is much less clear, however, whether this absorption of water vapor can hydrate the living cells of the leaves and, as a consequence, enhance physiological processes in such cells. The goal of this research was to determine if the absorption of atmospheric water vapor by the atmospheric epiphyte Tillandsia usneoides results in an increase in turgor pressure in leaf epidermal cells that subtend the large trichomes, and, by using chlorophyll fluorescence techniques, to determine if the absorption of atmospheric water vapor by leaves of this epiphyte results in increased photosynthetic activity. Results of measurements on living cells of attached leaves of this epiphytic bromeliad, using a pressure probe and of whole-shoot fluorescence imaging analyses clearly illustrated that the turgor pressure of leaf epidermal cells did not increase, and the photosynthetic activity of leaves did not increase, following exposure of the leaves to high humidity air. These results experimentally demonstrate, for the first time, that the absorption of water vapor following increases in atmospheric humidity in atmospheric epiphytic bromeliads is mostly likely a physical phenomenon resulting from hydration of non-living leaf structures, e.g., trichomes, and has no physiological significance for the plant's living tissues.     

The taxonomic position of Sphaerocarpos and Riella as indicated by their flavonoid chemistry

The major flavonoid glycosides of Sphaerocarpos texanus are luteolin 7-O-glucuronide and 7,4′-di-O-glucuronide. Riella americana and R. affinis both contain apigenin, chrysoeriol and luteolin 7-O-glucuronides but R. americana additionally contains luteolin 3′-O-glucuronide. This finding supports the inclusion of Sphaerocarpaceae and Riellaceae in the order Marchantiales rather than their separation into another order.     

Effects of ambient temperature,humidity, and age on wing-beat frequency of Periplaneta species

Wing-beat frequency of 2-week-old male Periplaneta americana cockroaches was measured during tethered flight at ambient temperatures from 19 to 35°C and 50 and 95% r.h. Between 19 and 27°C the frequency increased at a nearly constant rate (0·6 Hz/deg at 50% r.h.; 0·7 Hz/deg at 95% r.h.), but the rate of increase decreased markedly between 27 and 35°C. This decline differed from results of past investigations of wing-beat frequency for this species. Wing-beat frequencies at 95% r.h. were significantly higher than those at 50% r.h. for ambient temperatures between 27 and 35°C. reductions in wing-beat frequency at high temperatures and differences in wing-beat frequency between 50 and 95% r.h. may reflect decreases in internal thoracic temperature resulting from cuticular water loss.     

Thermogenic characteristics and evaporative water loss in the tree shrew (Tupaia belangeri)

Thermogenic characteristics and evaporative water loss were measured at different temperatures in Tupaia belangeri. The thermal neutral zone (TNZ) of T. belangeri was 30–35 °C. Mean body temperature was 39.76±0.27 °C and mean body mass was 100.86±9.09 g. Basal metabolic rate (BMR) was 1.38±0.03 ml O₂/g h. Average minimum thermal conductance (C_m) was 0.13±0.01 ml O₂/g h °C. Evaporative water loss in T. belangeri increased when the temperature rose; the maximal evaporative water loss was 3.88±0.41 mg H₂O/g h at 37.5 °C. The results may reflect features of small mammals in the sub-tropical plateau region: T. belangeri had high basal metabolic rate and high total thermal conductance, compared with the predicted values based on their body mass whilst their body temperatures are relatively high; T. belangeri has high levels of evaporative water loss and poor water-retention capacity. Evaporative water loss plays an important role in temperature regulation.