Effect of uncomplicated pregnancy on body water content and distribution in baboons

Body water content and distribution were estimated before, during, or after 32 pregnancies in baboons. Water content of the various compartments (in liters) correlated with body weight in both nonpregnant and pregnant baboons, and with length of gestation in pregnant baboons. In proportion to body weight (in ml/kg), most water compartments did not change significantly with length of gestation. Mean plasma volume and blood volume were higher during pregnancy than before or after.     

土壤温度和水分对长白山不同森林类型土壤呼吸的影响

在实验室条件下,将不同含水量的3种森林类型的土柱分别置于0、5、15、25和35℃条件下,进行土壤呼吸测定．结果表明,在0～35℃范围内。土壤呼吸速率与温度呈正相关．在一定含水量范围内(0．21～0．37kg·kg^-1),土壤呼吸随含水量的增加而升高,当含水量超出该范围,土壤呼吸速率则随含水量的变化而降低．土壤温度和水分对土壤呼吸作用存在明显的交互作用．不同森林类型土壤呼吸作用强弱存在显著差异,大小顺序为阔叶红松林>岳桦林>云冷杉暗针叶林．阔叶红松林土壤呼吸作用的最佳条件是土壤温度35℃、含水量0．37kg·kg^-1;云冷杉暗针叶林下的山地棕色针叶林土壤呼吸作用的最佳条件是25℃、0．21kg·kg^-1;岳桦林土壤呼吸作用的最佳条件是35℃、含水量0．37kg·kg^-1。但是．由于长白山阔叶红松林、云冷杉林和岳桦林处在不同的海拔带上,同期不同森林类型土壤温度各不相同,相差4～5℃,所以野外所测的同期山地棕色针叶林土呼吸速率应低于暗棕色森林土呼吸速率,山地生草森林土呼吸速率应高于山地棕色针叶林土的呼吸速率．     

Supercooling capacity of seeds and seedlings in Arabidopsis thaliana.

The influence of the water content of seeds and seedlings of Arabidopsis thaliana (Ecotype Columbia:2) on their supercooling capacity was investigated. Equilibration of the seeds to various air relative humidities resulted in final moisture contents ranging from 8 to 82% (dry weight basis). No supercooling point could be detected when the water content remained below 32.5%, and in seeds at just above this moisture level ice crystals started to form at -26 degrees C. However, cooling partly affected the germination of seeds down to a water content of 26.5%. Upon imbibition, the supercooling point of the seeds remained around -21.6 degrees C and rose sharply to -14.7 degrees C when visible germination started. It remained around -13 degrees C during the following 96 h while the water content of the seedlings increased from 155 to 870%. Hydrated seeds (above 32.5% water content), germinated seeds, and seedlings of Arabidopsis cannot survive being frozen.     

Differing actions of penetrating and nonpenetrating cryoprotective agents.

A two-step freezing technique has been used to examine the role of cryoprotective agents during cooling. Chinese hamster fibroblasts were cooled to various subzero holding temperatures and subsequently thawed or cooled to ?196 °C before thawing. Cells were suspended in various concentrations of dimethylsulfoxide (DMSO) or hydroxyethyl starch (HES) before freezing. The results indicated differing protective actions of DMSO and HES. These differences were verified using glycerol as either a penetrating or a nonpenetrating agent.The results are consistent with the concepts that cryoprotection is based on the avoidance or minimization of intracellular freezing and the minimization of damage to the cell from the environment of concentrated solutes during cooling, and that the colligative action of both penetrating and nonpenetrating agents allows the cells to survive the conditions for a reduction of cell water content during cooling thereby reducing the amount of intracellular freezing. The results indicate that penetrating and nonpenetrating agents accomplish this in different ways. Penetrating agents create the environment for a reduction of cell water content at temperatures sufficiently low to reduce the damaging effect of the concentrated solutes on the cells. Nonpenetrating agents osmotically “squeeze” water from the cells primarily during the initial phases of freezing at temperatures between ?10 and ?20 °C when these additives become concentrated in the extracellular regions.     

Biochemical Changes in Excised Leaves of Oryza sativa Subjected to Water Stress

Excised rice (Oryza sativa L. cv. Ratna) leaves were used to compare the changes in the levels of various biochemical intermediates and enzyme activities during senescence in turgid and water-stressed conditions. Chlorophyll, total protein and soluble protein content decreased but α-amino nitrogen content increased during the senescence of turgid leaves. In the leaves subjected to water stress, these changes were accelerated, the acceleration being greater with higher degree of water stress. Starch, soluble sugars, total carbohydrates and non-reducing sugar content decreased during senescence of turgid leaves. Water stress accelerated the changes in the levels of starch and non-reducing sugar, but the changes in the levels of soluble sugars and total carbohydrates were retarded. Reducing sugar content increased at first and then decreased in the turgid leaves, and water stress accelerated the change. The decline in the catalase activity and the increase in the peroxidase activity with time was faster in the water-stressed leaves than in the turgid leaves. Acid inorganic pyrophosphatase activity increased, but alkaline inorganic pyrophosphatase activity decreased during the senescence of turgid leaves, and such changes were accelerated by water stress. The results suggest that water stress does not accelerate all the processes connected with leaf senescence.     

Seasonal field analyses of water and fat content in the long-lived millipede Polyzonium germanicum (Diplopoda, Polyzoniidae)

Two hundred and seventy-nine Polyzonium germanicum individuals of various stadia were collected seasonally in winter, late spring-early summer (the breeding period) and early autumn. Fresh weight, dry weight and defatted dry weight were determined for each specimen. Seasonal changes in water content and fat content, expressed as percentages of defatted dry weight, were analysed in relation to body size and sex. Changes in water content were more pronounced in the smallest individuals (juveniles), whereas changes in fat content were more pronounced in the largest (adults). Seasonal fluctuations in water and fat content were similar in both sexes despite the sexual dimorphism of body weight. The results suggest the following relationships within the species life-cycle: (i) water content increases during the warm months (up to 295% for juveniles in early autumn), which coincides with the moulting period, (ii) Fat content increases subsequently to moulting; overall maxima are reached in early autumn (population mean = 62–5%), as well as in early summer for the young, (iii) Both water and fat content decrease (to about 150% and 50%, respectively) in winter; however, there is no evidence of starvation–at least in ovigerous females which increase in dry weight during that season, (iv) Fat content strongly decreases (below 30% in the largest specimens) in adults of both sexes during the breeding period.     

Body component growth and composition of the magpie Pica pica

Magpie nestling growth is documented as increments in body mass, tarsus length, and tenth primary length. A sample of 41 nestlings and eight adults was used to provide comparative data on changes in water content, lean dry mass, and fat content for 14 body components.
Changes in the composition of various components implicate water index (water content/ lean dry mass) as an indicator of tissue and nestling maturity. Lipid index (fat content/lean dry mass) for the whole body exhibited a sustained linear increase during the first two-thirds of the nestling period. About 80% of nestling body fat was located in the skin, body shell, and alimentary canal.
The state of development of particular components appeared to be related to the current functional requirements of the nestling. Thus the food processing components assumed an early significance, while the development of insulative and locomotory components was somewhat curtailed by comparison.     

Carcass composition of spur-winged geese with comments on reproduction and moulting

Spur-winged geese at Barberspan, an agricultural area in South Africa, had an average carcass composition of 64% water, 22% protein, 6% lipid, 6% minerals and 2% carbohydrate with an energy content of 21.6 kJ g^-1 DW. There were significant changes during the year in protein and lipid levels; they were lowest during the annual flightless wing moult. Protein and lipid levels also declined during breeding but this event had less effect on body reserves than moulting. The relationships between various body measurements and mineral content of the carcass (as an estimate of skeletal weight) were examined.     

Changes in germination, growth and soluble sugar contents of Sorghum bicolor (L.) Moench seeds under various abiotic stresses

The effect of various abiotic stresses on germination rate, growth and soluble sugar content in Sorghum bicolor (L.) Moench cv. CSH 6 seed embryos and endosperm during early germination was investigated. Under stress conditions germination, water potential and tissue water content decreased markedly. Subsequently, this reduction resulted in marked decreases in fresh weight both in embryos and endosperm. Conversely, a substantial increase in dry weight was observed. Furthermore, a considerable increase in the sugar contents in both embryo and endosperm was detected. The fructose level was always higher than glucose and sucrose in response to various stresses. However, as compared to the control the level of glucose and sucrose was higher in embryos and endosperm after stress treatments. Based upon these results a possible physiological role of sugars in the germination of sorghum seeds is discussed.     

Dielectric Properties of Frozen Biological Material

The origin of the relaxation observed in the organic materials studied here is most likely to be the same as that seen in various frozen water-in-oil emulsions. This conclusion is drawn from the similarity of the activation energies (? 30 kJ/mol), the similar dependences on the ice content and the range of frequencies covered by the relaxation. Observations previously made on the variation of relaxation frequency at ?80°C with time after death of various fish tissues may reflect either a change in the ice fraction of the tissue as protein degradation proceeds resulting in water being released, or water being taken up by the tissue from melting ice during storage at 0°C.     

Biochemical changes occurring during final maturation of eggs of some marine and freshwater teleosts

Biochemical changes which occur during post-vitellogenic meiotic maturation of oocytes were investigated by measuring the concentrations of various phosphorus-containing fractions of the ovaries and mature eggs of four marine species with pelagic eggs, plaice, Pleuronecles platessa , cod, Gadus morhua , haddock, Melanogrammus aeglefinus , and whiting, Merlangius merlangus , and three freshwater species with demersal eggs, rainbow trout, Salmo gairdneri , pike, Esox lucius , and powan, Coregonus lavarelus . In the former group, protein phosphate was deposited at normal vertebrate levels in the ovaries during vitellogenesis but was exhausted during maturation, its decrease correlating with the uptake of water which rendered the mature egg buoyant in sea water. In plaice, phospholipid phosphate declined slightly during maturation, while inorganic phosphate increased by an amount slightly less than that which disappeared from the protein fraction. No such changes occurred on maturation in these three fractions in the freshwater species, in which little or no water uptake occurred. In plaice, the approximately five-fold increase in the water content of the oocyte was accompanied by a corresponding five-fold increase in the amount of potassium, the major inorganic cation of the oocyte. These pelagic eggs appear to be unique among the eggs of vertebrates in their high water content ( c . 92%) and in the fact that the protein phosphate is almost entirely utilized before fertilization, while, in those freshwater fishes and other oviparous vertebrates that have been examined, the egg is of much lower water content (50–70%) and most of the protein phosphate, like the other major yolk constituents, is used during embryonic growth. This utilization at such an early stage in the life cycle constitutes an extreme example of heterochrony.     

Electrical conduction in hydrated collagen. I. Conductivity mechanisms

The electrical conductivity of bovine Achilles tendon with various amounts of adsorbed water was measuredas a function of temperature. The conduction appeared to be fully determined by the water of hydration. The current is probably primarily carried by protons at water contents up to 45% and by small ions at water contents beyond 65%. In both ranges of water content, a linear relation between activation energy and water and content was found. As to the lower range, this is explained by the action of Coulombic forces during the separation of proton–hydroxyl ion pairs. In two regions of water content a linear relation between the logarithm of the pre-exponential factor and the activation energy was found. There are, however, indications that at certain water contents the dissociation constant of the adsorbed water is several orders of magnitude higher than in liquid water.     

Effects of culture medium composition and PEG on hyperhydricity in Dendrobium officinale

Hyperhydricity is a physiological disorder during plant tissue culture that seriously affects regeneration and micropropagation. In this study, Dendrobium officinale plantlets were cultured on solid Murashige and Skoog (MS) medium supplemented with plant growth regulators and various concentrations of sucrose, agar, and polyethylene glycol (PEG)-6000 to explore the effect of osmotic stress on hyperhydricity. The results show that low concentrations of sucrose or agar, as well as PEG-6000 at various concentrations, significantly increase the hyperhydric rate of D. officinale, whereas high concentrations of sucrose or agar did not. Furthermore, high concentrations of PEG-6000 significantly increase total water content, free-water content, relative electrical conductivity, and peroxidase (POD) activity of D. officinale plantlets, whereas they significantly decrease bound-water content, proline content, soluble protein content, soluble sugar content, and superoxide dismutase (SOD) activity. These results indicate that PEG-6000 disrupts the antioxidant system and water metabolism in D. officinale plantlets, as well as increases cell membrane permeability, which might be the key factors for the occurrence of hyperhydricity in this species.

     

Southern elephant seal,Mirounga leonina: composition of milk during lactation

An analysis of milk constituents during various stages of lactation in the southern elephant seal Mirounga leonina was carried out. Forty-six milk samples were taken from 30 females throughout lactation during 1985, 1987, 1990 and 1991 on Stranger Point, King George Island, South Shetland Islands. Total nitrogen (TN), non-protein nitrogen (NPN), sugar, fat, ash and water were measured, and from some of these data true protein and energy content were calculated. The results showed a high degree of variation in water and fat concentrations among samples at different stages of lactation. During the first 20 days the fat content of milk increased from about 12 to approximately 52%, while water content fell from 70 to 33%. The composition of milk changes rapidly during the first days post-partum. Protein, minerals and sugar appear to remain stable after the fourth day of lactation. Milk samples contain significant levels of sugars; thin layer chromatography indicates the presence of lactose and glucose together with other unidentified components. There is evidence of a striking change in composition of the milk in the later part of lactation; the progressive increase in the fat:water ratio is abruptly reversed just prior to weaning.     

Serial estimates of body water content and distribution during the first postnatal month in baboons

Water content of the various body compartments was estimated serially during the first postnatal month in six term baboon neonates. In absolute volumes (mL), total body water, intracellular water, and plasma volume all increased linearly with body weight and postnatal age, although the effect of weight was predominant. In proportion to body weight (mL/kg), total body water, intracellular water, and plasma volume increased linearly with postnatal age whereas extracellular water and red cell volume decreased. There was no linear relation between the proportions of any of the water volumes and body weight.     

Morph‐specific differences in biochemical composition related to flight capability in the wing‐polyphenic Sitobion avenae

Flight performance at various times after emergence in the alate morph and age‐dependent changes in biochemical composition of winged and wingless morphs were evaluated in the wing‐polyphenic aphid Sitobion avenae (Fabricius) (Hemiptera: Aphididae). Alates exhibited the highest flight activity at 18–36 h after adult emergence. Throughout the nymphal and adult development, the whole‐body content of total lipid was significantly higher in the winged vs. wingless morph, whereas the content of water, soluble sugar, glycogen, phospholipid, and soluble protein showed significantly higher levels in the wingless vs. winged morph. There were no significant differences in the content of triglyceride and free fatty acid during nymphal and adult stages in both morphs. However, triglyceride content was significantly higher in the winged vs. wingless morph during adulthood. Differences in biochemical composition between morphs indicate that there is an energetic cost of flight capability. Our results from S. avenae adults showed that total lipid and triglyceride for the winged morph accumulated significantly to a maximum, and water content decreased significantly to a minimum, on days 1 and 2 after the final molt, exactly when the highest flight activity was reached. This study suggests that flight activity is associated with triglyceride and water content.     

Body water content and distribution in nonpregnant adult female baboons

Water contents of the various body water compartments were estimated in 16 nonpregnant adult female baboons and compared to human data. Total body water, extracellular water, and plasma volumes were determined by dilution studies. Intracellular water, interstitial water, blood volume, and red cell volume were calculated. The data were compatible with the finding that baboon females probably have less body fat than their human counterparts. Our data establish a basis for longitudinal studies of the changes in body water content and distribution during normal and pathological pregnancies.     

Effect of acetylation on the material properties of glucuronoxylan from aspen wood

The effect of the degree of acetylation of glucuronoxylan on solubility, water content and thermal properties was investigated. Aspen glucuronoxylan, isolated by alkali extraction from wood chips, was acetylated to various degrees of substitution through reaction with acetic anhydride in formamide and pyridine by varying the reaction time. The degree of acetylation was determined by ¹H NMR spectroscopy. The molecular weight was decreased only to a small extent during the reaction, as seen by size exclusion chromatography. It was found that acetylation strongly affects the solubility properties as well as the equilibrium water content of the glucuronoxylans upon exposure to humidity. Samples with a high degree of acetylation are soluble only in aprotic solvents, whereas non-acetylated glucuronoxylan is partially soluble in hot water. In the same surrounding relative humidity, acetylated samples have lower water content than non-acetylated samples. Acetylation prevents thermal degradation, as shown by thermogravimetric analysis under nitrogen. Acetylation to a degree of substitution of 1.2 also results in a glass transition temperature, which we studied using differential scanning calorimetry, making it possible to thermoprocess acetylated glucuronoxylan.     

Effect of Wilting on Carbohydrates during Incubation of Excised Bean Leaves in the Dark

Excised bean (Phaseolus vulgaris) leaves were used to compare the changes in various carbohydrates during dark incubation in a wilted and turgid condition. After a rapid (less than 1 hour) wilt, leaves were incubated at a constant water content (75% of original fresh weight).     

Survival of alginate-entrapped cells of Azospirillum lipoferum during dehydration and storage in relation to water properties

Survival of alginate-entrapped cells of Azospirillum lipoferum was studied during dehydration using a dry air stream and during prolonged storage at various constant water activity values (a_w). During the drying operation, the viability loss remained almost constant from the initial water content to 0.35 g water/g dry weight (DW) corresponding to a 98.5% water removal, strongly increased until a water content of 0.25 g/g DW and then stopped until the end of the drying operational (final a_w 0.18). A water content of 0.25 g/g DW (a_w=0.55) corresponded to the critical point of the moisture sorption isotherm curve from which water became restricted to the dry material. A high drying rate (5 g/g DW per hour) was shown to be more detrimental for cell viability than a low drying rate (1.18 g/g DW per hour). When the product was stored in a closed chamber with a regulated a_w (0.23), the number of living cells decreased during a short period (less than 15 days) corresponding to the product a_w stabilization, and then remained constant for more than 150 days. In addition, cell survival during storage was not affected by a_w values in the range 0–0.55. Above a_w=0.55, the higher the a_w and the storage duration, the lower the residual survival percentage. The influence of the drying and storage conditions on the cell death rate are discussed with regard to both the mechanisms generally involved in viability loss and the hydration properties of water. Correspondence to: A. Pareilleux