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1.
Munn AJ Dawson TJ 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2003,173(7):575-582
Generally, young growing mammals have resting metabolic rates (RMRs) that are proportionally greater than those of adult animals. This is seen in the red kangaroo (Macropus rufus), a large (>20 kg) herbivorous marsupial common to arid and semi-arid inland Australia. Juvenile red kangaroos have RMRs 1.5–1.6 times those expected for adult marsupials of an equivalent body mass. When fed high-quality chopped lucerne hay, young-at-foot (YAF) kangaroos, which have permanently left the mother's pouch but are still sucking, and recently weaned red kangaroos had digestible energy intakes of 641±27 kJ kg–0.75
day–1 and 677±26 kJ kg–0.75
day–1, respectively, significantly higher than the 385±37 kJ kg–0.75
day–1 ingested by mature, non-lactating females. However, YAF and weaned red kangaroos had maintenance energy requirements (MERs) that were not significantly higher than those of mature, non-lactating females, the values ranging between 384 kJ kg–0.75
day–1 and 390 kJ kg–0.75
day–1 digestible energy. Importantly, the MER of mature female red kangaroos was 84% of that previously reported for similarly sized, but still growing, male red kangaroos. Growth was the main factor affecting the proportionally higher energy requirements of the juvenile red kangaroos relative to non-reproductive mature females. On a good quality diet, juvenile red kangaroos from permanent pouch exit until shortly after weaning (ca. 220–400 days) had average growth rates of 55 g body mass day–1. At this level of growth, juveniles had total daily digestible energy requirements (i.e. MER plus growth energy requirements) that were 1.7–1.8 times the MER of mature, non-reproductive females. Our data suggest that the proportionally higher RMR of juvenile red kangaroos is largely explained by the additional energy needed for growth. Energy contents of the tissue gained by the YAF and weaned red kangaroos during growth were estimated to be 5.3 kJ g–1, within the range found for most young growing mammals.Abbreviations BMR
basal metabolic rate
- DEI
digestible energy intake
- MER
maintenance energy requirement
- MERg
maintenance plus growth energy requirement
- PPE
permanent pouch exit
- RMR
resting metabolic rate
- YAF
young-at-foot
Communicated by I.D. Hume 相似文献
2.
Pass GJ Foley WJ 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2000,170(3):185-192
The effect of the phenolic glycoside, salicin, on food intake of the common brushtail possum (Trichosurus vulpecula) was studied in a series of feeding experiments. Increasing the concentration of salicin in a diet of fruits and cereals
led to significant reductions of food intake in the short term (6 days). After prolonged (20 days) exposure to salicin, food
intake (19 g kg−0.75 day−1) was still reduced relative to controls (31 g kg−0.75 day−1) but not reduced to the same extent as in the short-term experiments. Nonetheless, over these 20 days, common brushtail possums
regulated their intake of salicin so as not to exceed a threshold limit of 1.9 ± 0.1 g kg−0.75 day−1. Manipulative experiments sought to determine whether this threshold intake was in response to pre-ingestive factors (taste)
or the post-ingestive consequences of ingesting salicin. Dietary salicin (0.17–5.0% DM) had no significant effect on nitrogen
balance or urea metabolism and injection of a specific serotonin receptor antagonist, ondansetron, did not lead to increases
in salicin intake as has been found for some other plant secondary metabolites. Similarly, administration of 1.3 g salicin
by gavage had no significant effect on the subsequent intake of salicin compared to controls that were gavaged with water.
We concluded that pre-ingestive factors were responsible for common brushtail possums limiting their intake of salicin-rich
diets rather than any measurable post-ingestive consequence of feeding.
Accepted: 7 December 1999 相似文献
3.
Bradshaw FJ Bradshaw SD 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2001,171(1):59-67
A nitrogen balance feeding trial was carried out with the marsupial honey possum, Tarsipes rostratus, using four pollen-honey diets varying in nitrogen content from 9.4 mg · g−1 to 2.3 mg · g−1 dry matter. The dietary maintenance nitrogen requirement (MNR) was determined by regression analysis as 89 ± 21 mg N · kg−0.75 · day−1 and the truly digestible MNR was 79 mg N · kg−0.75 · day−1.. Regressing nitrogen balance on daily nitrogen intake separately for ten males and seven females revealed that the slopes
of the fitted lines did not vary significantly, but the difference in the intercepts approached significance. This suggests
that the MNR for females may be lower than that of males. The nitrogen digestibility of the diet was 76% and the biological
value (BV) was 58%. A comparison of the MNR of the honey possum with that of other marsupials shows that it is indeed much
lower than that of herbivorous macropodid marsupials and is close to that of the sap- and gum-feeding sugar glider, Petarurus breviceps. The endogenous urinary nitrogen excretion (EUN) of the honey possum was 42 mg N · kg−0.75 · day−1 and a regression analysis with other published data showed that the EUN per unit basal heat production is significantly lower
than that of eutherian mammals. Measurements of the actual feeding rates of animals in the field, taken together with the
low MNR, do not lend support to the hypothesis that the honey possum exhibits a reduced rate of reproduction due to a deficiency
in dietary nitrogen. It is possible that the quality of nitrogen provided by pollen, as reflected in its composition of essential
amino acids, may be a limiting factor.
Accepted: 15 September 2000 相似文献
4.
Sandy clay loam soil was contaminated with 5000 mg kg−1 diesel, and amended with nitrogen (15.98 atom% 15N) at 0, 250, 500, and 1000 mg kg−1 to determine gross rates of nitrogen transformations during diesel biodegradation at varying soil water potentials. The observed
water potential values were −0.20, −0.47, −0.85, and −1.50 MPa in the 0, 250, 500, and 1000 mg kg−1 nitrogen treatments respectively. Highest microbial respiration occurred in the lowest nitrogen treatment suggesting an inhibitory
osmotic effect from higher rates of nitrogen application. Microbial respiration rates of 185, 169, 131, and 116 mg O2 kg−1 soil day−1 were observed in the 250, 500, control and 1000 mg kg−1 nitrogen treatments, respectively. Gross nitrification was inversely related to water potential with rates of 0.2, 0.04,
and 0.004 mg N kg−1 soil day−1 in the 250, 500, and 1000 mg kg−1 nitrogen treatments, respectively. Reduction in water potential did not inhibit gross nitrogen immobilization or mineralization,
with respective immobilization rates of 2.2, 1.8, and 1.8 mg N kg−1 soil day−1, and mineralization rates of 0.5, 0.3, and 0.3 mg N kg−1 soil day−1 in the 1000, 500, and 250 mg kg−1 nitrogen treatments, respectively. Based on nitrogen transformation rates, the duration of fertilizer contribution to the
inorganic nitrogen pool was estimated at 0.9, 1.9, and 3.2 years in the 250, 500, and 1000 mg kg−1 nitrogen treatments, respectively. The estimation was conservative as ammonium fixation, gross nitrogen immobilization, and
nitrification were considered losses of fertilizer with only gross mineralization of organic nitrogen contributing to the
most active portion of the nitrogen pool. 相似文献
5.
Jessica A. Coltrane Perry S. Barboza 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(6):905-918
North American porcupines are distributed across a wide variety of habitats where they consume many different species of plants.
Winter is a nutritional bottleneck for northern populations, because porcupines remain active when environmental demands are
high and food quality is low. We used captive porcupines to examine physiological responses to low-quality diets at high energy
demands during winter at ambient temperatures as low as −39°C. We did not observe an endogenous pattern of body mass gain
or loss when porcupines were fed a low nitrogen diet (1.1% dry matter) ad libitum through winter. Dry matter intake declined
from 43.6 to 14.6 g kg−0.75 d−1 even though ambient temperatures declined from −3 to −30°C, which indicates a seasonal decrease in metabolic rate. Porcupines
consuming white spruce needles maintained digestive efficiency for energy (61%) and neutral detergent fiber (NDF) (50%). However,
low requirements for energy (398 kJ kg−0.75 d−1) and nitrogen (209 mg kg−0.75 d−1) minimized the loss of body mass when intakes were low and plant toxins increased urinary losses of energy and nitrogen.
Porcupines were also able to tolerate low intakes of sodium, even when dietary potassium loads were high. Porcupines use a
flexible strategy to survive winter: low requirements are combined with a high tolerance for dietary imbalances that minimize
the use of body stores when demands exceed supply. However, body stores are rapidly restored when conditions allow. Porcupines
posses many physiological abilities similar to specialist herbivores, but retain the ability of a generalist to survive extreme
conditions by using a variety of foods. 相似文献
6.
Masahiko Hirata Nobumi Hasegawa Maki Nomura Haruko Ito Kangoro Nogami Tatsunobu Sonoda 《Ecological Research》2009,24(1):119-125
This study monitored deposition and decomposition of cattle dung in a grazed young Chamaecyparis obtusa (an evergreen conifer) plantation in southwestern Japan, as a part of exploring the impacts of livestock in the forest grazing
system. Animals defecated 10–19 times hd−1 day−1, producing feces of 2.2–3.5 kg DM and 33–73 g N per animal per day. The DM and N concentrations of feces ranged from 157–207 g DM kg−1 and 14.8−23.1 g (kg DM)−1, respectively. Occurrence of defecation was spatially heterogeneous, with feces being concentrated mainly on areas for resting
(forest roads, ridges and valleys) and moving (forest roads and along fence lines). Decomposition of dung pats was considerably
slow, showing the rates of 1.37–3.05 mg DM (g DM)−1 day−1 as DM loss. Decomposition was further slower on the basis of N release, 0.51–1.63 mg N (g N)−1 day−1, resulting in steadily increased N concentrations of dung pats with time after deposition. The results show that introduction
of livestock into a forest (i.e., forest grazing) may limit nutrient availability to plants, by redistributing nutrients into
areas with no vegetation (bare land and streams) and by establishing a large N pool as feces due to an imbalance between deposition
and slow release, though further studies are necessary for investigating the occurrence of slow dung decomposition in other
forest situations. 相似文献
7.
Delorme M Thomas DW 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(2):123-132
Nitrogen (N) and energy (E) requirements of the phyllostomid fruit bat, Artibeus jamaicensis, and the pteropodid fruit bat Rousettus aegyptiacus, were measured in adults that were fed on four experimental diets. Mean daily food intake by A. jamaicensis and R. aegyptiacus ranged from 1.1–1.6 times body mass and 0.8–1.0 times body mass, respectively. Dry matter digestibility and metabolizable
E coefficient were high (81.1% and 82.4%, respectively) for A. jamaicensis and (77.5% and 78.0%, respectively) for R. aegyptiacus. Across the four diets, bats maintained constant body mass with mean metabolizable E intakes ranging from 1357.3 kJ · kg−0.75 · day−1 to 1767.3 kJ · kg−0.75 · day−1 for A. jamaicensis and 1282.6–1545.2 kJ · kg−0.75 · day−1 for R. aegyptiacus. Maintenance E costs were high, in the order of 3.6–5.4 times the basal metabolic rate (BMR). It is unlikely that the E intakes
that we observed represent a true measure of maintenance E requirements. All evidence seems to indicate that fruit bats are
E maximizers, ingesting more E than required and regulating storage by adjusting metabolic output. We suggest that true maintenance
E requirements are substantially lower than what we observed. If it follows the eutherian norm of two times the BMR, fruit
bats must necessarily over-ingest E on low-N fruit diet. Dietary E content did affect N metabolism of A. jamaicensis. On respective low- and high-E diets, metabolic fecal N were 0.492 mg N · g−1 and 0.756 mg N · g−1 dry matter intake and endogenous urinary N losses were 163.31 mg N · kg−0.75 · day−1 and 71.54 mg N · kg−0.75 · day−1. A. jamaicensis required 332.3 mg · kg−0.75 · day−1 and 885.3 mg · kg−0.75 · day−1 of total N on high- and low-E diets, respectively, and 213.7 mg · kg−0.75 · day−1 of truly digestible N to achieve N balance. True N digestibilities were low (29% and 49%) for low- and high-E diets, respectively.
For R. aegyptiacus, metabolic fecal N and endogenous urinary N losses were 1.27 mg N · g−1 dry matter intake and 96.0 mg N · kg−0.75 · day−1, respectively, and bats required 529.8 mg · kg−0.75 · day−1 (total N) or 284.0 mg · kg−0.75 · day−1 (truly digestible N). True N digestibility was relatively low (50%). Based on direct comparison, we found no evidence that
R. aegyptiacus exhibits a greater degree of specialization in digestive function and N retention than A. jamaicensis. When combined with results from previous studies, our results indicate that all fruit bats appear to be specialized in their
ability to retain N when faced with low N diet.
Accepted: 24 November 1998 相似文献
8.
Chris J. Hulatt Aino-Maija Lakaniemi Jaakko A. Puhakka David N. Thomas 《Bioenergy Research》2012,5(3):669-684
Mass culture of microalgae is a potential alternative to cultivation of terrestrial crops for bioenergy production. However, microalgae require nitrogen fertiliser in quantities much higher than plants, and this has important consequences for the energy balance of these systems. The effect of nitrogen fertiliser supplied to microalgal bubble-column photobioreactor cultures was investigated using different nitrogen sources (nitrate, urea, ammonium) and culture conditions (air, 12% CO2). In 20 L cultivations, maximum biomass productivity for Chlorella vulgaris cultivated using nitrate and urea was 0.046 and 0.053 g L−1 day−1, respectively. Maximum biomass productivity for Dunaliella tertiolecta cultivated using nitrate, urea and ammonium was 0.033, 0.038 and 0.038 g L−1 day−1, respectively. In intensive bubble-column photobioreactors using 12% CO2, maximum productivity reached 0.60 and 0.83 g L−1 day−1 for C. vulgaris and D. tertiolecta, respectively. Recycling of nitrogen within the photobioreactor system via algal exudation of nitrogenous compounds and bacterial activity was identified as a potentially important process. The energetic penalty incurred by supply of artificial nitrogen fertilisers, phosphorus, power and CO2 to microalgal photobioreactors was investigated, although analysis of all energy burdens from biomass production to usable energy carriers was not conducted. After subtraction of the power, nitrogen and phosphorus energy burdens, maximum net energy ratios for C. vulgaris and D. tertiolecta cultivated in bubble columns were 1.82 and 2.10. Assuming CO2 was also required from a manufactured source, the net energy ratio decreased to 0.09 and 0.11 for C. vulgaris and D. tertiolecta, so that biomass production in this scenario was unsustainable. Although supply of nitrogen is unlikely to be the most energetically costly factor in sparged photobioreactor designs, it is still a very significant penalty. There is a need to optimise both cultivation strategies and recycling of nitrogen in order to improve performance. Data are supported by measurements including biochemical properties (lipid, protein, heating value) and bacterial number by epifluorescence microscopy. 相似文献
9.
Macrophyte presence is an indicator of enhanced denitrification and nitrification in sediments of a temperate restored agricultural stream 总被引:1,自引:0,他引:1
Stream macrophytes are often removed with their sediments to deepen stream channels, stabilize channel banks, or provide habitat
for target species. These sediments may support enhanced nitrogen processing. To evaluate sediment nitrogen processing, identify
seasonal patterns, and assess sediment processes relative to stream load, we measured denitrification and nitrification rates
in a restored third- to fourth-order agricultural stream, Black Earth Creek, Wisconsin, and estimated processing over a 10 km
reach. Our results show that sediments with submerged and emergent macrophytes (e.g., Potomageton spp. and Phalaris arudinacea) support greater denitrification rates than bare sediments (1.12 μmol N g−1 h−1 vs. 0.29). Sediments with macrophytes were not carbon limited and organic matter fraction was weakly correlated to denitrification.
The highest denitrification potential occurred in macrophyte beds (5.19 μmol N g−1 h−1). Nitrification rates were greater in emergent beds than bare sediments (1.07 μg N ml−1day−1 vs. 0.35) with the greatest nitrification rates during the summer. Total denitrification removal in sediments with macrophytes
was equivalent to 43% of the nitrate stream load (463.7 kg N day−1) during spring and nitrification in sediments with macrophytes was equivalent to 247% of summer ammonium load (3.5 kg N day−1). Although the in-channel connectivity to nitrogen rich water was limited, actual stream nitrogen loads could increase with
removal of macrophytes. Macrophyte beds and supporting fringing wetted areas are important if nitrogen management is a concern
for riparian stream restoration efforts. 相似文献
10.
This study focuses on selective feeding by developmental stages of two oceanic copepods, Calanus finmarchicus and Calanus helgolandicus from nauplii to adults. A mixture of four algal species of different biochemical composition, Prorocentrum nanum (dinoflagellate), Thalassiosira minima (diatom), Rhodomonas baltica (cryptophyte) and Dunaliella tertiolecta (chlorophyte), added in an equal biovolume, was used in three different experimental set-ups. In set-up 1 the algal species
were present as single cells of similar size (14 μm). In set-up 2 the diatom T. minima was present in chains of two or three cells and was therefore larger than the other algae, while the biovolume of all species
remained the same. In set-up 3, the diatom T. minima was excluded from the mixture. Feeding selectivity of the copepods was assessed in relation to the quality of the algal species
expressed in terms of carbon and nitrogen content, fatty acid composition, and chain length of the diatom. The results show
that younger stages and adult females of C. finmarchicus and C. helgolandicus did not show a preference for an algal species when the algae were of similar size. In the feeding experiments where the
diatoms were offered as chains, both copepod species showed a selective behaviour only on the basis of algal size. Individual
ingestion rates increased from 0.4 to 0.7 μg C day–1 for nauplii of both species to 5 μg C day–1 for adult females of C. helgolandicus to 12 μg C day–1 for C. finmarchicus. Individual filtration rates ranged from 5 ml day–1 for C. finmarchicus nauplii to 70–98 ml day–1 for adult females, and from 3 ml day–1 for C. helgolandicus nauplii to 35–46 ml day–1 for adult females. Ingestion and filtration rates per unit body carbon decreased gradually in both copepod species with increasing
body carbon. The daily ingested amount of food decreased for C. finmarchicus from 124–134% of the body carbon for nauplii to 19% of the body carbon for adult females, and for C. helgolandicus from 117–137% of the body carbon for nauplii to 13–26% of the body carbon of adult females.
Electronic Publication 相似文献
11.
12.
Effects of sequential procedures required for cryopreservation of embryos excised from the recalcitrant seeds of Haemanthus montanus were assessed ultrastructurally and in conjunction with respiratory activity and the rate of protein synthesis. Fresh material
(water content, 5.05 ± 0.92 g g−1 dry mass) afforded ultrastructural evidence of considerable metabolic activity, borne out by respiratory rates. Neither exposure
to glycerol nor sucrose as penetrating and non-penetrating cryoprotectants, respectively, brought about degradative changes,
although increased vacuolation and autophagy accompanied both, while respiratory and protein synthetic activity were not adversely
affected. Glycerol-cryoprotected embryos flash dried to water contents >0.4 g g−1 showed organised ultrastructural features and considerable autophagy consistent with metabolic activity, and although respiratory
activity was lower, protein synthesis rate was enhanced relative to fresh material. However, at water contents <0.4 g g−1, embryo tissue presented a mosaic of cells of variable density and ultrastructural status, but trends in rates of respiration
and protein synthesis remained similar. Flash drying after sucrose exposure was accompanied by considerable ultrastructural
abnormality particularly at water contents <0.4 g g−1, lysis of individual and groups of cells and considerable depression of respiration, but not of protein synthesis. Success,
assessed as ≥50% axes forming seedlings after cryogen exposure, was obtained only when glycerol-cryoprotected embryos at water
contents >0.4 g g−1—in which the degree of vacuolation remained moderate—were rapidly cooled. The outcomes of this study are considered particularly
in terms of the stresses imposed by prolonged, relatively slow dehydration and ultimate water contents, on embryos showing
considerable metabolic activity. 相似文献
13.
Lang YJ Bai L Ren YN Zhang LH Nagata S 《Extremophiles : life under extreme conditions》2011,15(2):303-310
Using ectoine-excreting strain Halomonas salina DSM 5928T, we developed a new process for high-efficiency production of ectoine, which involved a combined process of batch fermentation
by growing cells and production by resting cells. In the first stage, batch fermentation was carried out using growing cells
under optimal fermentation conditions. The second stage was the production phase, in which ectoine was synthesized and excreted
by phosphate-limited resting cells. Optimal conditions for synthesis and excretion of ectoine during batch fermentation in
a 10 l fermentor were 0.5 mol l−1 NaCl and an initial monosodium glutamate concentration of 80 g l−1 respectively. The pH was adjusted to 7.0 and the temperature was maintained at 33°C. In phosphate-limited resting cells medium,
monosodium glutamate and NaCl concentration was 200 g l−1 and 0.5 mol l−1, respectively, as well as pH was 7.0. The total concentration of ectoine produced was 14.86 g l−1, the productivity and yield of ectoine was 7.75 g l−1 day−1 and 0.14 g g−1, respectively, and the percentage of ectoine excreted was 79%. These levels of ectoine production and excretion are the highest
reported to date. 相似文献
14.
Clemens G. Borkenstein Josef Knoblechner Heike Frühwirth Michael Schagerl 《Journal of applied phycology》2011,23(1):131-135
The present study reviews the options of cultivating the green alga, Chlorella emersonii, under photoautotrophic conditions with flue gas derived from a cement plant. It was conducted in the Lafarge Perlmooser
plant in Retznei, Austria, where stone coal and various surrogate fuels such as used tyres, plastics and meat-and-bone meal
are incinerated for heating limestone. During 30 days of cultivation, flue gas had no visible adverse effects compared to
the controls grown with pure CO2. The semi-continuous cultivation with media recycling was performed in 5.5-L pH-stat photobioreactors. The essay using CO2 from flue gas yielded a total of 2.00 g L−1 microalgal dry mass and a CO2 fixation of 3.25 g L−1. In the control, a total of 2.06 g L−1 dry mass was produced and 3.38 g L−1 CO2 was fixed. Mean growth rates were between 0.10 day−1 (control) and 0.13 day−1 (flue gas). No accumulation of flue gas residues was detected in the culture medium. At the end of the experiment, however,
the concentration of lead was three times higher in algal biomass compared to the control, indicating that cultures aerated
with this type of flue gas should not be used as food supplements or animal feed. 相似文献
15.
This study was designed to identify rhizobial strains specific to greengram expressing higher tolerance against insecticides,
fipronil and pyriproxyfen, and synthesizing plant growth regulators even amid insecticide-stress. Of the 50 bradyrhizobial
isolates, the Bradyrhizobium sp. strain MRM6 showed tolerance up to 1,600 μg mL−1 against each of fipronil and pyriproxyfen. The tolerant Bradyrhizobium sp. (vigna) produced plant growth promoting substances in substantial amounts, both in the presence and absence of insecticides. The
strain MRM6 was further used to investigate its impact on greengram grown in soils treated with 200 (the recommended dose),
400 and 600 μg kg−1 soil of fipronil and 1,300 (the recommended dose), 2,600 and 3,900 μg kg−1 soil of pyriproxyfen. Fipronil at 600 μg kg−1 soils and pyriproxyfen at 3,900 μg kg−1 soils had greatest toxic effects and decreased plant biomass, symbiotic efficiency, nutrient uptake and seed yield of greengram
plants. The Bradyrhizobium sp. (vigna) inoculant when used with fipronil and pyriproxyfen significantly increased the measured parameters compared to the plants
grown in soils treated solely with the same concentration of each insecticide. This study inferred that the Bradyrhizobium sp. (vigna) strain MRM6 may be exploited as bio-inoculant to increase the productivity of greengram exposed to insecticide-stressed
soils. 相似文献
16.
Andrzej K. Siwicki Zdzisław Zakęś Elżbieta Terech-Majewska Krzysztof Kazuń Agnieszka Lepa Edward Głąbski 《Reviews in Fish Biology and Fisheries》2010,20(3):435-439
Influence of beta-1.3/1.6-glucan (Macrogard) on the innate immunity and protection against Aeromonas hydrophila in tench (Tinca tinca (L.)) was assessed. Macrogard was fed at doses of 0, 0.5, 1 and 2 g kg−1 of pellets for 1 month. The blood, spleen and head kidney from 10 fish of each group were separated and analysed for immunity
parameters. Twenty tench from each group were infected with A. hydrophila. Macrogard at doses 1 and 2 g kg−1 of feed significantly (P < 0.05) increased the phagocytic activity of macrophages and proliferative response of mitogens stimulated lymphocytes. The
same doses significantly (P < 0.05) increased lysozyme activity and Ig level in serum, compared to the control and dose 0.5 g kg−1 of feed. The challenge test showed that Macrogard reduced mortality of tench after experimental infection (5–35%). 相似文献
17.
Susumu S. Abe Takashi Kotegawa Taisuke Onishi Yoshinori Watanabe Toshiyuki Wakatsuki 《Ecological Research》2012,27(1):219-227
This study investigated the influence of mound-building termites on soil particle dynamics on the land surface and in soil-forming
processes by examining the amount of soil particles in mound structures of Macrotermes bellicosus in a highly weathered Ultisol of tropical savanna. Soil particle turnover via the mounds was estimated using particle stock
data and soil turnover data from previous studies. A 4-ha study plot with six mounds of relatively uniform shape and size
was investigated. Soil mass constituting the mounds was 6,166 ± 1,581 kg mound−1 within which the mound wall and nest body accounted for 5,002 ± 1,289 and 1,164 ± 293 kg, respectively. The mound wall contained
a significantly larger amount of clay (252 ± 9.97 g kg−1) balanced with a lower sand content (676 ± 26.5 g kg−1) than in the adjacent surface (Ap1) horizon, (46.4 ± 12.8 g clay kg−1; 866 ± 83.2 g sand kg−1); the nest body had much higher clay content (559 ± 51.0 g kg−1) but less sand (285 ± 79.2 g kg−1) than the mound wall. As a result, the mounds of M. bellicosus accumulated clay of 2,874 ± 781 kg ha−1 (corresponding to 2.52% of clay stock in the Ap1 horizon) along with an estimated clay turnover rate of 169 kg ha−1 year−1. These findings suggest a positive feedback effect from termite mound-building activity on soil particle dynamics in tropical
savanna ecosystems: M. bellicosus preferentially use subsoil material for mound construction, resulting in relocation of illuvial clay in the subsoil to the
land surface where clay eluviation from the surface soil and its illuviation in the subsoil are major soil-forming processes. 相似文献
18.
Sachin Kumar Surendra P. Singh Indra M. Mishra Dilip K. Adhikari 《Journal of industrial microbiology & biotechnology》2009,36(12):1483-1489
A yeast strain Kluyveromyces sp. IIPE453 (MTCC 5314), isolated from soil samples collected from dumping sites of crushed sugarcane bagasse in Sugar Mill,
showed growth and fermentation efficiency at high temperatures ranging from 45°C to 50°C. The yeast strain was able to use
a wide range of substrates, such as glucose, xylose, mannose, galactose, arabinose, sucrose, and cellobiose, either for growth
or fermentation to ethanol. The strain also showed xylitol production from xylose. In batch fermentation, the strain showed
maximum ethanol concentration of 82 ± 0.5 g l−1 (10.4% v/v) on initial glucose concentration of 200 g l−1, and ethanol concentration of 1.75 ± 0.05 g l−1 as well as xylitol concentration of 11.5 ± 0.4 g l−1 on initial xylose concentration of 20 g l−1 at 50°C. The strain was capable of simultaneously using glucose and xylose in a mixture of glucose concentration of 75 g l−1 and xylose concentration of 25 g l−1, achieving maximum ethanol concentration of 38 ± 0.5 g l−1 and xylitol concentration of 14.5 ± 0.2 g l−1 in batch fermentation. High stability of the strain was observed in a continuous fermentation by feeding the mixture of glucose
concentration of 75 g l−1 and xylose concentration of 25 g l−1 by recycling the cells, achieving maximum ethanol concentration of 30.8 ± 6.2 g l−1 and xylitol concentration of 7.35 ± 3.3 g l−1 with ethanol productivity of 3.1 ± 0.6 g l−1 h−1 and xylitol productivity of 0.75 ± 0.35 g l−1 h−1, respectively. 相似文献
19.
M. A. Sobrado 《Trees - Structure and Function》2009,23(2):429-437
This study estimated the construction const (CC) and maintenance cost (MC) of leaf tissue on the basis of dry mass (CCMass, MCMass) and leaf area (CCArea, MCArea), as well as the maximum leaf gas exchange capacity, so as to examine leaf cost:benefit relationship in six dominant species
of the ‘Bana’ vegetation. Minimum and maximum CCMass averaged 1.71 ± 0.03 and 1.78 ± 0.03 g glucose g−1. The CCMass showed a statistically significant positive correlation with crude fibre, and tended to decline as leaves were larger. Thus,
smaller leaves tended to be built out of a more expensive material than that found in species bearing larger leaves. The average
CCArea of the ‘Bana’ species was 376 ± 15 g glucose m−2. A robust correlation was found between CCArea with leaf dry mass to leaf area ratio, as well as with leaf thickness, but not with leaf density. MCMass (g glucose g−1 day−1) and MCArea (g glucose m−2 day−1) were positively correlated. Maximum and minimum MCMass increased significantly with protein and lipid content, respectively. Maximum carbon assimilation (A
max) was positively correlated with CCArea. All the species operated at high stomatal conductance (g
s) and C
i/C
a which suggested low short-term water use efficiency. Potential nitrogen use efficiency (PNUE = A
max/N) averaged 35.4 ± 1.8 mmol CO2 mol−1 N. As the sclerophylly index (g crude fibre g−1 protein) increased, the ratio of CCArea to A
max increased significantly. This result suggests a trade-off between investments in an expensive resistant sclerophyllous leaf
which should maximize carbon gain in the long term. 相似文献
20.
M. Delorme D. W. Thomas 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1996,166(7):427-434
Nitrogen (N) and energy (E) requirements were measured in adult Carollia perspicillata which were fed on four experimental diets. Bats ate 1.3–1.8 times their body mass ⋅ day-1 and ingested 1339.5–1941.4 kJ ⋅ kg-0.75 ⋅ day-1. Despite a rapid transit time, dry matter digestibility and metabolizable E coefficient were high (83.3% and 82.4%, respectively),
but true N digestibility was low (67.0%). Mass change was not correlated with E intake, indicating that bats adjusted their
metabolic rate to maintain constant mass. Bats were able to maintain constant mass with digestible E intake as low as 1168.7 kJ ⋅ kg-0.75 ⋅ day-1 or 58.6 kJ ⋅ . Metabolic fecal N and endogenous urinary N losses were 0.87 mg N ⋅ g-1 dry matter intake and 172.5 mg N ⋅ kg-0.75 ⋅ day-1, respectively, and bats required 442 mg N ⋅ kg-0.75 ⋅ day-1 (total nitrogen) or 292.8 mg N ⋅ kg-0.75 ⋅ day-1 (truly digestible nitrogen) for N balance. Based on E and N requirements and digestibilities, it was calculated that non-reproductive
fruit bats were able to meet their N requirements without resorting to folivory and without over-ingesting energy. It was
demonstrated that low metabolic fecal requirements allowed bats to survive on low-N diets.
Accepted: 23 June 1996 相似文献