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1.
Małgorzata Zalewska Justyna Lema-Rumińska Natalia Miler Magdalena Gruszka Weronika Dąbal 《In vitro cellular & developmental biology. Plant》2011,47(3):375-378
The subject of investigation was Chrysanthemum x grandiflorum (Ramat.) Kitam., ‘Satinbleu’. Leaf explants and internodes were excised from the middle part of the donor sterile plant.
Two methods of explant inoculation were applied: explants were placed polarly and horizontally. Modified MS medium (Murashige
and Skoog 1962), supplemented with 11.4 μM indoleacetic acid and 2.7 μM 6-benzylaminopurine, were prepared to induce adventitious bud formation.
Four dates of explant inoculation on the medium were tested: January 15, April 15, July 15, and October 15. Thus, regeneration
occurred in winter, spring, summer, and autumn. In the present study, a more intensive regeneration in ‘Satinbleu’ chrysanthemum
was observed in summer and autumn than in spring and winter, irrespective of the kind of explant and the inoculation method. 相似文献
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Large species of kangaroo rats (family Heteromyidae) make extensive underground caches of seeds. During collection and storage, seeds become inoculated with fungal spores, most of which are common pernicious storage moulds in human agriculture systems. The moulds and their metabolites may be beneficial or detrimental, depending on the species of mould and the growth conditions. Feeding experiments were conducted to determine the preferences for mouldy seeds by Dipodomys spectabilis. Results showed that kangaroo rats prefer slightly mouldy seeds over very mouldy seeds, dry seeds, and unmouldy, imbibed seeds, apparently taking advantage of beneficial effects of moulds while avoiding the liabilities. 相似文献
5.
Two trials were conducted to evaluate the influence of season of the year and altered photoperiod on libido and scrotal circumference (SC). A 30-minute serving-capacity test was used to measure ram libido. the measures of libido were reaction time (RT), time from entry into the pen to first mount and/or service, total mounts (M), and total services (S). The serving-capacity test was conducted by placing a ram with four estrus-induced ewes and measuring RT and counting M and S. Prior to each serving-capacity test, SC was measured for each ram. Rams were tested every two weeks. In Trial I, eleven two-year-old Rambouillet rams from each of three selection lines -a high line (four rams; selected on the basis of high prolificacy), a low line (three rams; selected on the basis of low prolificacy) and a random bred control line (four rams) - were used in a one-year study. Rams were exposed to ambient conditions throughout the year. Rams were more active during the short days of fall and winter, i.e. normal breeding season, as evidenced by a greater number of total mounts and services plus a shorter reaction time. Selection line affected reproductive parameters measured, with the high line having more M and S and a shorter RT than the low line. However, SC was larger in the low line. In Trial II twelve rams were divided into two groups of six. The control group was exposed to ambient conditions from April 18 through July 24. The treated group was exposed to eight hours of light and 16 hours of darkness (8L:16D) from April 18 through July 24, simulating short days of fall and winter. Total services (S) in the 30-minute test interval were higher for rams subjected to the 8L:16D treatment (P<0.01; 2.7+/-0.2 vs 1.6+/-0.2 for 8L:16D and control, respectively). SC was 31.7+/-0.2 vs 30.2+/-0.2 for 8L:16D and control, respectively (P<0.01). Total mounts in 30 minutes were not affected by treatment (6.9+/-0.8 vs 5.7+/-0.8 for 8L:16D and control, respectively; P>0.10). No significant differences in any of the reproductive parameters between treatment groups were observed during the first 28 days. However, there were significant differences (P<0.05) observed between 8L:16D rams and control rams for SC during 42 to 84 days and S between days 42 to 70, respectively. Serving-capacity tests carried out about one month following the end of altered photoperiod trial showed no significant differences between treated and control rams, thus indicating that treatment had no carry-over effect. 相似文献
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Understanding the ways environmental signals, regulate reproduction and reproductive behavior of desert adapted rodents is a major gap in our knowledge. In this study, we assessed the roles of photoperiod and diet salinity, as signals for reproduction. We challenged desert adapted common spiny mice, Acomys cahirinus, males and females with osmotic stress, by gradually increasing salinity in their water source - from 0.9% to 5% NaCl under short and long days (SD and LD, respectively). Photoperiodicity affected testosterone levels, as under LD-acclimation, levels were significantly (p<0.05) higher than under SD-acclimation. Salinity treatment (ST) significantly reduced SD-acclimated male body mass (W(b)) and testis mass (p<0.005; normalized to W(b)). ST-LD-females significantly (p<0.005) decreased progesterone levels and the numbers of estrous cycles. A reduction in white adipose tissue (WAT) to an undetectable level was noted in ST-mice of both sexes under both photoperiod regimes. Receptors for vasopressin (VP) and aldosterone were revealed on testes of all male groups and on WAT in control groups. Our results suggest that photoperiod serves as an initial signal while water availability, expressed by increased salinity in the water source, is an ultimate cue for regulation of reproduction, in both sexes of desert-adapted A. cahirinus. We assume that environmental changes also affect behavior, as water seeking behavior by selecting food items, or locomotor activity may change in extreme environment, and thus indirectly affect reproduction and reproductive behavior. The existence of VP and aldosterone receptors in the gonads and WAT suggests the involvement of osmoregulatory hormones in reproductive control of desert adapted rodents. 相似文献
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We find that there are moderate differences in the electrical polarizabilities of normal and various hemophilic canine blood
platelets. The technique of dielectrophoresis, using the effect of nonuniform fields on neutral bodies, was used to perform
rapid assays of the platelets. At present the dielectrophoretic test can only distinguish reliably between relatively large
groups of animals on a statistical basis. The present technique shows a unique ability however, to distinguish even between
normal canine platelets and the transmitter female canine platelets.
In studies of the effects of various chemical agents upon the dielectrophoresis of platelets, inhibitors such as NaF, sodium
iodacetate, NaCN, and NaN3 had marked effects at low concentration. Ions such as Na+ K+, Mg++, and La+++, as well as NO3
−, SO4
=, and mellitic ion had lesser effects. In some cases the presence of trace quantities of the chemical agent “stabilizes” the
cellular dielectrophoretic response, enabling the platelet to continue to be attracted by the nonuniform field for longer
than usual. The CN− and F− ions appear to do this. This may have useful application.
From the shape of the frequency spectrum of the dielectrophoretic response we suggest that the peaks at about 0.1 to 10 MHz
imply a Maxwell-Wagner type of response, typical of an interface between bulk regions of differing conductivity, as at the
cell boundary. From a lack of low frequency response, we suggest that the platelet interface with the surrounding aqueous
medium must be singularly free of ionic double layers — or at least that the ionic double layers present must be of unusually
low charge density.
The technique of dielectrophoresis has been used in comparative study of canine blood platelets, from (1) normal dogs, (2)
female dogs that transmit Factor VIII deficiency to their offspring, (3) male dogs with Factor VIII deficiency, and (4) female
dogs with Factor VIII deficiency. The study showed that differences exist between the 4 groups of dogs in the average dielectrophoretic
responses at 1 MHz. The effect of several chemical agents, i.e., NaCN and NaF on normal canine platelets was to effectively
stabilize the platelets against deteriorationin vitro. 相似文献
8.
The effects of kallikrein, thrombin, and plasmin on interaction of acetylcholine and noradrenaline with receptors of the isolated portal vein of guinea-pigs were studied. The functional activity of receptors was studied by the pharmacokinetic method. It was found that kallikrein and thrombin do not disturb the kinetics of agonist interaction with receptors, whereas the magnitude of isometric vascular contractions dramatically decreased after plasmin treatment and becomes disproportionate to the concentration of neurotransmitters. Exposure of the portal vein to kallikrein or thrombin caused different changes in the sensitivity and quantity of active cholino- and adrenoreceptors. These proteolytic enzymes reduced the sensitivity of receptors to noradrenaline and increased it to acetylcholine. Exposure to kallikrein brought about a decrease in the quantity of active cholinoreceptors and a rise in the number of adrenoreceptors. The treatment of the vessels with thrombin resulted in a decrease in the number of active adrenoreceptors. The number of active cholinoreceptors remained unchanged. 相似文献
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E G Vornovitski? V B Ignat'eva A I Marchuk N A Len'kova 《Biulleten' eksperimental'no? biologii i meditsiny》1987,103(3):279-281
The effect of human serum diluted in Tyrode solution (1:1) on the cardiac contractility has been studied. Fragments of the right auricle myocardium from patients with congenital and acquired heart disease have been used to study serum effect on the contraction force. Myocardial strips were repeatedly stimulated with electrical impulses at a frequency of 0.1 to 1.5 Hz. All the perfusion solutions were maintained at 31-33 degrees C and Ca++ ion concentration was 2 +/- 0.2 mM/l. The serum increased the contraction force in the isolated myocardial fibers from patients with congenital and acquired heart disease. Positive inotropic serum action on the myocardium of patients with acquired heart disease was accompanied by a marked diminution of mechanical oscillations. At the same time human serum does not affect the form of force-frequency curves in both types of the preparations. The results suggest that human serum increases calcium ion homeostasis in the cardiac cells of patients during contraction-relaxation cycle. 相似文献
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C G Beebe R Schemmel O Michkelsen 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1976,151(2):395-399
In the first experiment, weanling rats were fed a grain ration or one of three semipurified diets high in fat, sucrose, or cornstarch. Rats in each dietary group were divided into two subgroups, one of which drank distilled deionized water whereas the other group drank 2% NaCl solution. Blood pressure and sodium intake were individually measured for each rat at weekly intervals for a 10-week period. Rats receiving the salt solution had higher mean blood pressures (127-178 mmHg) than rats offered distilled water (108-127 mmHg). When drinking solutions were the same, more severe rises in blood pressure occurred in rats fed the semipurified diets than in those rats fed grain. In a second experiment, rats were fed one of the four diets used in the first experiment; however, they received a 1% NaCl drinking solution for 9 weeks followed by a 1.5% NaCl solution for an additional 9 weeks. At Week 18, pressures among these groups of rats ranged from 136-140 mmHg, regardless of diet. 相似文献
12.
Jameel M. Al-Khayri Christine E. Shamblin Edwin J. Anderson 《In vitro cellular & developmental biology. Plant》1996,32(4):227-232
Summary This study was conducted to establish and optimize a regeneration system for adapted U.S. rice genotypes including three commercial
rice cultivars (LaGrue, Katy, and Alan) and two Arkansas breeding lines. Factors evaluated in the study were genotype, sugar
type, and phytohormone concentration. The system consisted of two phases, callus induction and plant regeneration. In the
callus induction phase, mature caryopses were cultured on MS medium containing either 1% sucrose combined with 3% sorbitol
or 4% sucrose alone, and 0.5 to 4 mg·L−1 (2.26 to 18.10 μM) 2,4-D with or without 0.5mg·L−1) (2.32 μM) kinetin. In the plant regeneration phase, callus was transferred to 2,4-D-free MS medium containing 0 or 2 mg·L−1 (9.29 μM) kinetin combined with 0 or 0.1 mg·L−1 (0.54 μM) NAA. Callus induction commenced within a week, independent of the treatments. Callus growth and plant regeneration, however,
were significantly influenced by interactions among experimental factors. Generally, the greatest callus growth and plant
regeneration were obtained with 0.5 mg·L−1 (2.26 μM) 2,4-D and decreased with increasing 2,4-D concentrations. Kinetin enhanced callus growth only when combined with 0.5 mg·L−1 (2.26 μM) 2,4-D, and 4% sucrose. Inducing callus on kinetin-containing medium generally enhanced regeneration capacity in the presence
of sucrose but not with a sucrose/sorbitol combination. Media containing sucrose alone generally supported more callus proliferation,
but the sucrose/sorbitol combination improved regeneration of some cultivars. NAA and kinetin had little effect on regeneration. 相似文献
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Aino Rummukainen Riitta Julkunen-Tiitto Mikko Räisänen Tarja Lehto 《Plant and Soil》2007,292(1-2):13-23
The increase in concentrations of phenolic compounds in boron (B) deficiency has been demonstrated in many herbaceous plant
species, but information on woody plants is scarce. It has been suggested that accumulation of phenolic compounds plays a
role in the development of cold hardiness in herbaceous plants but also that B deficiency decreases winter hardiness. Here
we study the effects of B nutrition on phenolic compounds in Norway spruce (Picea abies L.) in the course of cold acclimation. Phenolic compounds were analysed in Norway spruce seedlings from three different B-fertilisation
treatments in two harvests: non-acclimated and cold-acclimated seedlings. Norway spruce phenolic compounds consisted mainly
of condensed tannins. During B deficiency, condensed tannins and monocoumaroyl–astragalin der. 1 increased in non-acclimated
seedlings. The increase in tannins was 21%, which was nearly significant. However, the effect of B on phenolic compounds was
almost absent in cold-acclimated seedlings. The condensed tannin concentration increased much more with time in the simulated
autumn than due to B deficiency, and we conclude that the B effect was probably not large enough to be important for the hardening
of the seedlings. The total phenolic concentrations more than doubled during the course of cold hardening suggesting that
phenolics have a role in the winter hardiness in Norway spruce. 相似文献
14.
Emericella desertorum Samson et Mouchacca spec. nov. is described and illustrated. It differs from the other Emericella species by the large ascospores with low crests. An Aspergillus conidial state was not observed. Additional information on the morphology and physiology of Emericella fruticulosa (Raper et Fennell) Malloch et Cain and Aspergillus egyptiacus Moubasher et Moustafa is given. The osmophilic and halophilic properties occurring within the genus Aspergillus are discussed. 相似文献
15.
Sodium and potassium uptake of rice panicles as affected by salinity and season in relation to yield and yield components 总被引:4,自引:0,他引:4
Asch Folkard Dingkuhn Michael Wittstock Christine Doerffling Karl 《Plant and Soil》1999,207(2):133-145
Salinity is a major yield-reducing stress in many arid and/or coastal irrigation systems for rice. Past studies on salt stress
have mainly addressed the vegetative growth stage of rice, and little is known on salt effects on the reproductive organs.
Sodium and potassium uptake of panicles was studied for eight rice cultivars in field trials under irrigation with saline
and fresh water in the hot dry season and the wet season 1994 at WARDA in Ndiaye, Senegal. Sodium and potassium content was
determined at four different stages of panicle development and related to salt treatment effects on yield, yield components
and panicle transpiration. Yield and yield components were strongly affected by salinity, the effects being stronger in the
HDS than in the WS. The cultivars differed in the amount of salt taken up by the panicle. Tolerant cultivars had lower panicle
sodium content at all panicle development stages than susceptible ones. Panicle potassium concentration decreased with panicle
development under both treatments in all cultivars, but to a lesser extent in salt treated susceptible cultivars. Grain weight
reduction in the early panicle development stages and spikelet sterility increase in the later PDS were highly correlated
(p < 0.01) with an increase in panicle sodium concentration in both seasons, whereas reduction in spikelet number was not.
The magnitude of salt-induced yield loss could not be explained with increases in sodium uptake to the panicle alone. It is
argued that the amount of sodium taken up by the panicle may be determined by two different factors. One factor (before flowering)
being the overall control mechanism of sodium uptake through root properties and the subsequent distribution of sodium in
the vegetative plant, whereas the other (from flowering onwards) is probably linked to panicle transpiration.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Victoria R. Smith Cor J. Vink Ruedi G. Nager James Ross Adrian M. Paterson 《Journal of Insect Conservation》2014,18(3):397-405
The seasonal abundance of Latrodectus katipo Powell, 1871, a declining spider species endemic to coastal dunes in New Zealand, was observed in two different plant communities: an endemic sedge, Ficinia spiralis A. Rich. and an exotic grass, Ammophila arenaria (L.) Link. Using artificial cover objects (ACOs), presence/absence data was collected for L. katipo in the two plant communities. ACOs were positioned at Kaitorete Spit, which supports a healthy population of L. katipo, adjacent to F. spiralis or A. arenaria. ACOs were checked over four seasons. L. katipo were found significantly more often in ACOs placed next to F. spiralis as opposed to A. arenaria and its presence was highest in summer. Conserving L. katipo will involve reducing the amount of A. arenaria in New Zealand’s sand dunes. Studies monitoring L. katipo population dynamics should do so in summer when they are most abundant. 相似文献
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Four diverse disturbance types,namely,farmland,rotationaUy grazed grassland,overgrazed grassland and forbidden grazing grassland,were identified in the Alashan desert region of Inner Mongolia.Rodents were sampled in April,July and October in 2002 and 2003 using the trap-day method.Their spatial and temporal niches among the four disturbance types were assessed using the Shannon-Wiener niche breadth index and the Pianka niche overlap index.The Shannon-Wiener niche breadth index was the highest for Allactaga sibirica and Meriones meridianus (0.925 and 0.908,respectively),intermediate for Cricetulus eversmanni,Phodopus roborovskii and Citellus dauricus (0.789,0.782 and 0.711,respectively),and lowest for Cardiocranius paradoxus (0.003).The Pianka niche overlap indices of six-paired species were the highest and varied from 0.900 to 1.000,suggesting their spatial niche overlapped almost completely.Conversely,the spatial niche overlap index for Meriones unguiculatus,Cardiocranius paradoxus,and Salpingotus kozlovi was zero,thus indicating a complete absence of competition among them.In addition,the temporal niche breadth and overlap indices varied greatly in relation to disturbance types and season.The level of temporal niche overlap in spring and autumn was low while in summer it was high.For all disturbance types and for each season,the temporal niche overlap index of Meriones meridianus and Cricetulus barabansis was always highest but for Meriones unguiculatus and Salpingotus kozlovi always lowest. 相似文献
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Four diverse disturbance types, namely, farmland, rotationally grazed grassland, overgrazed grassland and forbidden grazing
grassland, were identified in the Alashan desert region of Inner Mongolia. Rodents were sampled in April, July and October
in 2002 and 2003 using the trap-day method. Their spatial and temporal niches among the four disturbance types were assessed
using the Shannon-Wiener niche breadth index and the Pianka niche overlap index. The Shannon-Wiener niche breadth index was
the highest for Allactaga sibirica and Meriones meridianus (0.925 and 0.908, respectively), intermediate for Cricetulus eversmanni, Phodopus roborovskii and Citellus dauricus (0.789, 0.782 and 0.711, respectively), and lowest for Cardiocranius paradoxus (0.003). The Pianka niche overlap indices of six-paired species were the highest and varied from 0.900 to 1.000, suggesting
their spatial niche overlapped almost completely. Conversely, the spatial niche overlap index for Meriones unguiculatus, Cardiocranius paradoxus, and Salpingotus kozlovi was zero, thus indicating a complete absence of competition among them. In addition, the temporal niche breadth and overlap
indices varied greatly in relation to disturbance types and season. The level of temporal niche overlap in spring and autumn
was low while in summer it was high. For all disturbance types and for each season, the temporal niche overlap index of Meriones meridianus and Cricetulus barabansis was always highest but for Meriones unguiculatus and Salpingotus kozlovi always lowest.
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Translated from Acta Ecologica Sinica, 2005, 25(10): 2,637–2,643 [译自: 生态学报] 相似文献