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1.
Growth and reproduction of batches and isolated Limax valentianus
Férussacslugs reared under long-day photoperiods were compared with
thosereared under short-day photoperiods combined with higher
temperaturesduring the dark period. Weight increase in L. valentianus
occurredin three distinct phases: an initial phase of rapid growth
(infantilephase), followed by a phase with a smaller increase in
weight(juvenile phase) and finally a phase with minimal growth,
duringwhich reproduction occurred (adult phase). This phase ended
witha weight decrease, due to senescence. Short days associatedwith
an increase in temperature during the night reduced thereproductive
rate, but did not affect growth. Long days werefavourable for
reproduction. Growth rate was fastest in isolatedindividuals reared
under long days and warm nights, while reproductionwas greatest in
isolated individuals reared under long daysand cool nights. Fertility
generally decreased with age, butegg production of slug batches
evolved through a maximum, occurringbefore mean life span. High slug
density reduced reproductiverate and longevity. (Received 22 December 2000; accepted 10 October 2000) 相似文献
2.
Corrélations simples (r) et pondérées (rp)entre S. setosa (trois stades cumulés), S. minima etS. inflata (stade 1), S. bipunctata, et les quatre paramétreshydrologiques retenus. aSeuil de signification 5%. bSeuil designification 1% 相似文献
3.
Leymarie Juliette; Damerval Catherine; Marcotte Lucette; Combes Valerie; Vartanian Nicole 《Plant & cell physiology》1996,37(7):966-975
In order to detect gene products involved in Arabidopsis droughtadaptive strategy, 2D-PAGE protein patterns of two auxin-insensitivemutants, axr1, axr2, differentially affected in specific droughtresponses, were compared to the wild-type Columbia ecotype,in well-watered and drought-stressed conditions. Coupled tocomputer analysis of polypeptide amounts, 2D-electrophoresisrevealed subtle changes in protein expression induced by progressivedrought stress and/or mutations affecting the auxin responsepathway. The differential protein patterns of axr1 and axr2 were consistentwith their contrasting drought responses. The specific leafand root protein patterns of axr1 showed that this mutationdisrupts drought responses related to auxin regulation. In particular,the near absence of drought rhizogenesis in axr1 was associatedwith a root protein pattern closer to the well-watered thanto the water-stressed axr2 and Columbia wild-type root proteinpatterns. Also, the largely different effects of axr1 and axr2mutations suggest that they affect different pathways in auxinresponse. Several sets of polypeptides, whose regulation wasaffected by drought and/or mutation, were thus detected. Thesepolypeptides could play a role both in the auxin and the droughtresponse pathways. Their identification, through microsequencing,should be most informative.
4Current address: Laboratoire de BioénergétiqueCellulaire, Département d'Ecophysiologie Végétaleet de Microbiologie, Centre d'Etudes de Cadarache, 13108 SaintPaul lez Durance, France 相似文献
4.
Diel periodicity of Subantarctic copepods: relationships between vertical migration, gut fullness and gut evacuation rate 总被引:3,自引:0,他引:3
A zooplankton community in the Polar Frontal Zone north of SouthGeorgia was sampled for 5 days in February 1994. Feeding ofvarious copepodite stages of six copepod species was assessedby a series of gut fluorescence/gut evacuation experiments.Feeding periodicity was compared to vertical distribution andmigration patterns, as revealed by Longhurst Hardy PlanktonRecorder (LHPR) and ring net catches. Despite chlorophyll alevels reaching only 0.8 mg m3 and daily carbon rationsbased on phytoplankton intake being low, feeding of all thecopepods was restricted mainly to the 8 h night-time perid.During the daytime, the epipelagic community was verticallydispersed within the top 100 m. At night, upward migration bymost species led to a convergence of almost all zooplanktersin the upper half of the surface mixed layer. However, large-amplitudevertical migrations which crossed the thermocline were performedonly by Metridia lucens and Pleuromamma robusta. Although feedingby both migrants and non-migrants was mainly at night, therewas no diel signal in gut evacuation rate. The gut evacuationrates of the nine copepod species and stages differed significantly(5-fold) and were negatively related to the extent of theirdiel vertical migration. The long gut-passage times of the migratoryspecies, M.lucens and P.robusta, would have allowed them timeto defaecate some of the food eaten near the surface at depth,contributing to an active carbon transfer out of the mixed layer.However, their scarcity at this site meant that their grazingcomprised only -<1.4% of total copepod ingestion, so theircombined gut flux is likely to have been negligible (-0.4 mgcarbon day1). 相似文献
5.
Rancillac Michel; Kaur-Sawhney Ravindar; Staskawicz Brian; Galston Arthur W. 《Plant & cell physiology》1976,17(5):987-995
Avena leaf protoplasts from varieties susceptible (cv. Park)and resistant (cv. Victory) to victorin incorporate the labelfrom 3H-L-leucine, 3H-uridine and 3H-thymidine into trichloroaceticacid-insoluble materials at comparable rates. When incubatedin the presence of the toxin, susceptible protoplasts beginto lyse after a short period of time; the effect on resistantprotoplasts is minimal. Victorin also significantly reducesincorporation of label from leucine and to a lesser extent fromuridine and thymidine into susceptible protoplasts but has anegligible effect on resistant protoplasts. Pretreatment ofsusceptible leaves with cycloheximide but not kinetin protectsagainst the subsequent action of victorin on apparent proteinsynthesis and lysis of protoplasts.
1Permanent address: Institut National de la Recherche Agronomique,Station de Physiologie et Biochemie Végétales,"La Grande Ferrade", Centre de Recherches de Bordeaux, 33 Pont-de-la-Maye,Bordeaux, France.
2School of Forestry and Environmental Studies, Yale University.
3Supported by grant GI-32958 of the RANN program of the NationalScience Foundation to A. W. Galston. We are indebted to WhitneyAdams, jr. for expert assistance. (Received April 10, 1976; ) 相似文献
6.
Elongation growth of abraded hypocotyl sections of Vigna unguiculataunder xylem perfusion was markedly promoted a few minutes afterthe application of an acid aerosol generated from a solutionof HCl. At the beginning of the acid-induced growth, intracellularpressure (Pi) began to decrease and the membrane potential betweenthe symplast and the xylem apoplast (Vpx) began to depolarize.Subsequently, Pi and Vpx remained at a reduced level and a depolarizedlevel, respectively, while the promotion of elongation growthcontinued for more than 4 hours. The electrogenic componentof the xylem membrane potential (Vpxact) gradually increasedto about twice that before acid treatment. There was a closecorrelation between the enhanced growth and the decrease inintracellular pressure within 30 min after application of acidbut little correltion after 60 min. By contrast, there was littlecorrelation between the promotion of growth and the activityof the xylem pump after 30 min while a close correlation wasobserved after 60 min. It is inferred that the acid-induced activation of water uptakeconsists of two major processes, in series, that are drivenby different forces: the rapid uptake of water for more than30 min, driven by hydrostatic force generated by loosening ofcell walls; and a long-lasting enhancement of water uptake forat least 4 h, which is driven by osmotic force that is generatedby the canal system within the xylem. (Received October 17, 1994; Accepted January 23, 1995) 相似文献
7.
Significance of Polyamines for Flowering in Spirodela punctata 总被引:1,自引:0,他引:1
Spirodela punctata strain O 5, a quantitative long-day plant,flowers only when ethylene-diamine-di-o-hydroxyphenylaceticacid (EDDHA) or salicylic acid was added to the nutrient medium[Scharfetter et al. (1978) Z. Pflanzenphysiol. 87: 445]. Undersuch conditions, cyclohexylamine and methylglyoxal-bis(guanylhydrazone)(both blockers of polyamine synthesis) inhibited flowering withoutsignificant effects on vegetative growth. Supply of spermidineabolished completely the inhibitor effects, but cannot replacethe EDDHA effect on flowering.
1Dedicated to Prof. O. H. Volk, Wurzburg, on his 85th birthday.
2Present address: Facultad de Ciencias Forestales, UniversidadAutónoma de Nuevo León. Ap. Post. 41, 67700 Linares,Nuevo León, México. (Received October 19, 1988; Accepted February 3, 1989) 相似文献
8.
9.
Predation by ciliates on a metalimnetic Cryptomonas population: feeding rates, impact and effects of vertical migration 总被引:1,自引:0,他引:1
Pedros-Alio Carlos; Massana Ramon; Latasa Mikel; Garci-Cantizano Josefina; Gasol Josep M. 《Journal of plankton research》1995,17(11):2131-2154
Deep algal maxima are frequently overlayed by dense populationsof ciliates, rotifers and crustaceans. This has been interpretedas evidence of heavy predation on the algae, although the impactof this predation has never been determined experimentally.We determined the vertical and seasonal distribution of thealga Cryptomonas phaseolus and its most relevant predators,the ciliates Coleps sp. and Prorodon sp., forming metalimneticmaxima in Lake Cisó. On several dates, in situ feedingrates of ciliates were determined by three independent methods:(i) epifluorescence counts of ingested algal cells togetherwith estimates of the food turnover time of the ciliates; (ii)in situ incubations with radioactively labeled algae: (iii)HPLC determination of alloxanthine content in the predator sizefraction. Feeding rates varied between 0.07 and 0.64 Cryptomonasciliate1 h1. We then calculated integrated predationon the algae. using the functional response of the ciliatesand the vertical distribution of each population. We found thateven though the ciliates were always food saturated, their predationimpact on Cryptomonas was not very large: as an average, 525%of the biomass of Cryptomonas was removed daily by the ciliates.Finally, we studied the effects of the diel vertical movementsof these populations on predation impact. By migrating intothe sulfide-rich hypolimnion during the night, Cryptomonas couldreduce its predation losses by 38%. Thus, the algae were protectedfrom predation during several hours of each diel cycle and maintaineda very large biomass throughout stratification, although thisresulted in a very slow growth. Slow growth, coupled to largebiomass, seems to be a general feature of metalimnetic accumulationsof organisms. 相似文献
10.
Leaves of different ages from B. calycinum were exposed to 14CO2in light during day and night. The labelling pattern on thechromatogram differed with leaf age. Young leaves had similarpatterns to those of C3 plants during both day and night. Matureleaves showed high incorporation of 14C into C4 acids, especiallyat night. In contrast, no significant difference with leaf agewas observed in the pattern of dark 14CO2 fixation products.Study of the enzyme activity and the content of titratable acidat each leaf age suggested that high incorporation of 14C inC4 acids during the night was due to the simultaneous absorptionof CO2 by both enzymes RuDPcarboxylase and PEPcarboxylase. (Received November 24, 1977; ) 相似文献
11.
The number, size (mm3 pellet 1) and total volume of fecalpellets produced (mm3 h1) by Boeckella titicacae increasedwith concentration of Chlorella and natural seston in threedifferent lakewaters from Bahia de Puno and Lago Grande of LakeTiticaca and nearby Laguna Arapa. The three lakewaters differedin the size and number of fecal pellets produced at seston concentrations>0.5 mg dry wt l1. However, the total volume of fecalpellets egested varied little. Large-sized food (>10 µg)resulted in larger pellets but smaller total fecal production.Food concentration had parallel effects on the production offeces and on feeding rates. Both fecal production and feedingincreased linearly with food concentration with saturation between5 and 7.5 x 105 Chlorella ml1 (3.75.6 mg dry wtl1). Varied responses in fecal production when fed differentsize fractions of lake seston suggest Boeckella has a complexand flexible feeding behavior. Feeding preferences of B.titicacaeand B.occidentalis (Ivlev index) for two seston size fractionsare generally reflected by fecal production. 相似文献
12.
[14C]-assimilation rates were measured on cultures of two unicellulargreen algae (Chlamydomonas sp. and Oocystis sp.) as a functionof light intensities (saturation curves), under steady lightand also under rapidly alternating high and low light intensities.Assimilation rates vary according to the frequency of the intermittentlight regime and it falls under two categories: (1) at 0.1 and0.2 Hz, the assimilation rate is equal to the average of therates observed at high and low light intensities under steadylight, and (2) under 1.0, 1.6 and 10 Hz the assimilation rateis equal to the rate observed under a mean steady irradiance.Moreover, the range of assimilation rates at a given frequencydepends on the difference between the high and the low intensities.Batch cultures of Oocystis sp. have been grown under intermittentlight of 0.1, 1.0 and 10.0 Hz (same mean intensity). Growthrate under intermittent light of 0.1 Hz is 40% lowerthan the control under steady light. Photosynthetic potential(PBmax)and efficiency () change with the growth stages of thecultures. At the end of the logarithmic growth phase, both photosyntheticparameters are maximum at 1.0 Hz and minimum at 0.1 Hz. Averagecell concentrations of chlorophyll a increase as the frequencyof the light regime decreases. During the log phase, concentrationof carotenoids relative to chlorophyll a increases at 1.0 Hz,decreases at 0.1 Hz, and remains constant at 10.0 Hz. Underclear sky conditions, wave-induced light fluctuations in thephotic layer may therefore enhance primary production, especially(1) in the lower part of the photic layer, where low frequencylight changes might cause cell chlorophyll a to increase, and(2) at a depth of 14 m, where the main frequencies (ofthe order of 1.0 Hz), might cause a significant increase ofboth the photosynthetic potential (PBmax)and efficiency ().
1Contribution au programme du GIROQ (Groupe interuniversitairede recherches océanographiques du Québec)
2Adresse actuelle: Centre de recherches en nutrition, UniversitéLaval, Québec, Qué. G1K 7P4, Canada 相似文献
13.
POPULATION STRUCTURE OF BIOMPHALARIA GLABRATA, INTERMEDIATE SNAIL HOST OF SCHISTOSOMA MANSONI IN GUADELOUPE ISLAND, USING RAPD MARKERS 总被引:1,自引:0,他引:1
LANGAND J.; THERON A.; POINTIER J.P.; DELAY B.; JOURDANE J. 《Journal of Molluscan Studies》1999,65(4):425-433
Nine populations of the snail Biomphalaria glabrata, sampledin 1992 and in 1994 in the
Guadeloupean focus of schistosomiasis,were studied using random amplified polymorphic DNA
(RAPD) markers.The detected polymorphism was low with 11 polymorphic markers.A
canonical analysis of the genetic polymorphism showed a significantand large differentiation
between the nine populations studiedin a restricted area of 45 km2. A Mantel
ttest indicateda significant correlation between the genetic differentiationand the
geographical distance. A significant but smaller differentiationbetween a northern and southern
group was also observed usingcanonical analysis. A comparison over time has been done.
Corresponding author: A. Théron. Laboratoire de Biologie
Animale,UMR 5555 CNRS, Centre de Biologie et d'Ecologie Tropicale et
Méditerranéenne,Université, 52 Av. de Villeneuve, 66860 Perpignan
Cedex,France. Tel: +33 4 68 66 21 83 Fax: +33 4 68 66 22 81 E-mail:theron{at}univ-perp.fr (Received 26 October 1998; accepted 30 December 1998) 相似文献
14.
Legendre L.; Demers S.; Garside C.; Haugen E.M.; Phinney D.A.; Shapiro L.P.; Therriault J.-C.; Yentsch C.M. 《Journal of plankton research》1988,10(1):1-6
A large (1200 1) seawater sample from the Gulf of Maine waskept under constant temperature and light conditions for a periodof 72 h. Circadian variations were observed in the photosyntheticcapacity (PBmax) and efficiency (B); these occurred in phase,and were not related to changes in chlorophyll concentrations.Such observations are consistent with the hypothesis that oscillationsin photosynthetic characteristics of natural phytoplankton aremediated by an endogenous circadian rhythm.
1 Bigelow Laboratory contribution 87023 and a contribution tothe programs of GIROQ (Groupe interuniversitaire de recherchesoceanographiques du Québec) and of the Maurice-LamontagneInstitute 相似文献
15.
Experiments are described in which the normal geotropic responsesof the roots of Pisum sativum seedlings have been compared withthose obtained in the presence of auxins (indole-3-acetic acidand 2:4-dichlorophenoxyacetic acid) in the external medium.The courses of positive curvature resulting from short exposures(40 minutes) and also subsequent recovery phenomena on a horizontalklinostat have been followed. A photographic recording techniqueallowed the determination of absolute growth-rates of both upperand lower sides of the root during the course of each experiment. Positive curvature started at its maximum rate (0.300.32deg./min.) after a reaction time of 11.5 minutes and continuedconstant at that rate for about 60 minutes after stimulationceased. Recovery took place at a similar rate of curvature andwas complete after a further 150200 minutes. During thephase of positive curvature overall root growth-rates were considerablyreduced and were slowly restored to normal during recovery. Low concentrations (1 part in 1011) of both auxins increasedthe rate of positive curvature by 3040 per cent. andshortened the reaction time roughly in proportion. The growth-ratesof both sides of the root were increased to the same extentduring both curvature and recovery. High concentrations (108IAA and 3.108 2: 4-D)reduced the rates of curvature by 50 per cent., lengthened thereaction time, and inhibited the growth of both sides of theroot during both curvature and recovery. Neither concentration of either auxin otherwise affected thetime course of response and recovery. It is suggested that geotropic response is due to the de novoproduction of an endogenous inhibitor in the extending cellsof the lower side of the root whence it may later spread tothe upper side. The complete independence of the growth actionsof this inhibitor and of the applied auxins suggests that itis not indole-3-acetic acid or any similar compound. Recoverymay be very largely independent of both inhibitor and auxinsand due to the action of another growth factor limiting celllength. The implications of these findings and of the attendant theoriesare fully discussed. 相似文献
16.
The planktonic shrimp, Lucifer faxoni, lives to an age of 3040days off the Texas coast. In the laboratory, the shrimp took28.9 and 18.9 days to reach sexual maturity at 22 and 30°Crespectively. Oviposition was observed at night between 20.00and 23.00. Females attach eggs to the 3rd pereiopods and broodthem until the nauplii emerge. Multiple broods are produced,giving a maximal lifetime fecundity of >140 eggs per female.In addition, females may also be able to synchronize the timeof their hatching to occur at night, perhaps to further reducemortality due to predation and cannibalism. A rapid turnoverof generations, each with a short adult lifespan, sequentialspawnings, and protection of eggs until hatching, characterizesthe life strategy of this small shrimp. Adult L.faxoni are carnivorous.However, their feeding appendages do not exclude the possibilityof omnivory. The maximal, dry-weight-based, specific ingestionrate was 0.7 day1. Feeding activity was not affectedby either time of day or light regime. 相似文献
17.
Grazing rates of the freshwater ciliate Balanion planctonicum determined by flow cytometry 总被引:1,自引:0,他引:1
Feeding of Balanion planctonicum on the cryptomonad Rhodomonassp. was recorded in vivo at 23 min intervals by flowcytometry. Ingestion rates were 1.61.7 algal cells ciliate1h1. On average, 2030 min elapsed between ingestionand egestion. 相似文献
18.
STEINGROVER EVELIENE; WOLDENDORP JUULTJE; SIJTSMA LOLKE 《Journal of experimental botany》1986,37(8):1093-1102
The leaf elongation rate (LER) of spinach leaves during theday was twice that during the night when grown at a photon fluxdensity of 145 µmol m2 s1. All leaves showedthe same LER-pattern over 24 h. Due to low turgor, LER was lowin the afternoon and in the first hours of the night until wateruptake restored full turgor. Osmotic potential remained constantdue to increased nitrate uptake and starch degradation in thisperiod. LER increased to high rates in the second part of thenight and in the morning. The lower rate in the dark comparedto the light was not caused by the lower night temperatures,as increased photon flux density during growth resulted in equalrates in the light and the dark. Increased relative humiditydecreased LER and afternoon rates were most sensitive to waterstress. A low light night period did not changeLER-pattern during the night or on the following day. We concludethat nitrate is not an obligatory osmoticum during the nightand can be exchanged for organic osmotica without decreasingLER. During the night the turgor is first restored by increasingwater uptake, nitrate uptake and starch degradation. This resultedin increased leaf fresh weight in this period. Thereafter, elongationincreased by simultaneous uptake of nitrate and water. Nitrateconcentration was, therefore, constant in the older leaves.In the younger leaves nitrate concentration increased to replacesoluble carbohydrates. The vacuoles of the old leaves were filledwith nitrate before those of the young leaves. Key words: Spinacia oleracea L., nitrate accumulation, osmotic potential, organic acids 相似文献
19.
Aggregate stages of the salps Thalia democratica, Cyclosalpaaffinis and Salpa cylindrica collected by SCUBA diving in theMid-Atlantic Bight were fed with naturally occurring food assemblages.This is one of the few studies where salps have been fed withnatural food assemblages. The estimated clearance rate for allspecies based on disappearance of chlorophyll varied from 82to 444 mL individual1 day1. Cell counts showedthat T. democratica mostly ingested carbon from autotrophicnanoflagellates and autotrophic dinoflagellates. Ingestion byS. cylindrica was primarily on larger prey, such as dinoflagellates,while C. affinis ingested auto- and heterotrophic nanoflagellates.All main prey types ingested by salps corresponded to thosethat contributed most to biomass at each experimental station.Thus, salps fed on naturally occurring particles primarily inproportion to prey biomass and to their mechanical capacityto be retained and ingested. Feeding by salps on dinoflagellatesand ciliates implies that they may act not only as potentialcompetitors with microzooplankton, but also as consumers ofthem. 相似文献
20.
Zooplankton samples were collected in Mejillones Bay, northernChile (23°00'15'S, 70°26'43'W ). Sampling was conductedat 4 h intervals, for 24 h during three seasons, austral spring(October 2000), summer ( January 2001) and winter (August 2001)at three different strata (025, 2550 and 50100m). Five species of chaetognaths were collected. Sagitta enflatawas the most abundant species, representing up to 65% of allchaetognaths in total numbers, followed by Sagitta bierii, makingup 34% of the total abundance of chaetognaths. S. enflata wasdistributed mainly above the Oxygen Minimum Zone, while S. bieriiremained below this zone. Feeding rates were relatively constantwithin the upper layer (025 m depth), for each samplingdate, averaging 1.2 prey S. enflata day1, and decreasingwith depth. Gut content analyses demonstrated that predationwas principally focused on small copepods (<1500 µm),with greatest feeding activity occurring at night. The dailypredation impact on the total standing stock of small copepodsvaried seasonally between 6% in spring and 0.4% in winter. Thispercentage may represent a negligible impact on the entire copepodcommunity, but it is relevant at the species or genus level,since S. enflata removed more than 20% of the standing stockof Centropages brachiatus and Corycaeus sp. Thus, during someperiods of the year, chaetognaths may strongly influence theabundance and size distribution of copepods in coastal upwellingecosystems. 相似文献