克氏原螯虾

从形态、习性、繁殖和幼体发育等7个方面介绍了克氏原螯虾的生物学特性,指出它对人类有益的方面,以及对水利、农业、淡水养殖业的危害及其可能造成食用者食物中毒的不利方面。     

Shelter-seeking behavior of crayfish, <Emphasis Type="Italic">Procambarus clarkii,</Emphasis> in elevated carbon dioxide

Carbon dioxide has been found to produce various negative consequences for a number of aquatic species and is projected to rise in the future for many aquatic ecosystems. Crayfish act as indicators of water quality and function as keystone species in aquatic food webs; however, there is a paucity of research on how crayfish may respond to elevated CO₂. This study quantified how shelter-seeking behavior in freshwater crayfish (e.g., family Cambaridae), a behavior critical for survival and fitness, may change following exposure to elevated pCO₂. Red Swamp crayfish (Procambarus clarkii, Girard, 1852) were exposed to one of three potential levels of dissolved CO₂ that could be found in freshwater basins currently or under future climate change conditions: Control (2 levels as the respective initial exposure. The treatment aquarium contained a shelter and was divided into three equal sections based on proximity to that shelter. Crayfish proximity to the shelter (defined by the tank sections) in the treatment aquarium was monitored every 5 s for a 2-min trial. Crayfish spent differing amounts of time in differing zones of the experiment and had different levels of activity, depending on their pCO₂ exposure; crayfish acclimated to High pCO₂ increased their time spent hiding and decreased their overall activity when compared to the Low pCO₂ and Control treatments. Augmented shelter-seeking behavior may affect crayfish social hierarchies, feeding, mating, and mortality, which could generate cascading effects on the ecology of many freshwater ecosystems.     

Effect of variation in photoperiod and light intensity on oxygen consumption, lactate concentration and behavior in crayfish Procambarus clarkii and Procambarus digueti

The effects of light intensity and duration on metabolic and behavioral parameters of two species of crayfish, Procambarus clarkii and Procambarus digueti, were studied. Sixty animals of each species were submitted to high irradiance conditions of two different photoperiod lengths, one normal light/dark (LD) 12:12 and one extreme LD 20:4 for 2 weeks. Hemolymph, lactate and oxygen consumption were determined throughout the experimental period. Simultaneously in 18 additional animals of each species, motor activity was individually recorded under the same control and experimental conditions. Both species showed a decrease in oxygen uptake and an increase in hemolymph lactate concentration. The statistical significance of this finding was higher for LD 20:4. This extreme condition evoked a significant decrease of motor activity in P. clarkii and a high mortality rate in P. digueti. P. digueti did not survive after the experiment, whereas P. clarkii survived and adapted to the laboratory conditions. Changes in metabolic and behavioral parameters could indicate different adaptation abilities in these species.     

武汉地区克氏原螯虾繁殖期的研究

为探究武汉地区克氏原螯虾(Procambarus clarkii)繁殖期的问题,采用石蜡切片的方法,对武汉地区自然群体中克氏原螯虾雌雄成体的生殖腺进行了周年观察研究。结果表明,武汉地区成年克氏原螯虾的卵母细胞发育不同步,在4~5月以及9~10月的卵巢中都有大量成熟期的卵子,同时也含有少量卵黄发生前期或初期的卵母细胞。6~7月和11月都可见产后恢复期的卵巢,内含少量未产出的正在退化的过熟卵和一些卵黄发生前期或初期的卵母细胞。精巢发育的年周期变化没有卵巢变化的那么明显,但也可以看到,在4~6月和9~10月,含精子细胞和精子的精小管的比例大大增加,而在其他时期,含精原细胞和精母细胞的精小管比例较多。这些结果提示,武汉地区克氏原螯虾一年有两个繁殖高峰期,一个在4~5月,另一个在9~10月。     

The effects of acetylcholine, carbamylcholine and gamma-aminobutyric acid on uropod motoneurons in the crayfish Procambarus clarkii and Cambaroides japonicus

The effects of acetylcholine (ACh), carbamylcholine and gamma-aminobutyric acid (GABA) on the spike activity of uropod motoneurons were investigated electrophysiologically in the crayfish Procambarus clarkii Girard and Cambaroides japonicus de Haan. High concentrations of ACh were required to bring about an increase in the spike discharge of uropod motoneurons while carbamylcholine, which is not destroyed by cholinesterase, caused a marked increase in the motoneuron spike discharge even in low concentrations. Application of GABA in concentrations of 10(-5)-10(-2) M caused the decrease in the spike discharge of uropod motoneurons. Under the condition that the synaptic transmission onto uropod motoneurons was blocked by perfusing EGTA containing Ca2+-free saline with high-Mg2+, ACh increased the spike discharge of uropod motoneurons whereas GABA decreased it. The results suggested that ACh and GABA function as excitatory and inhibitory transmitters, respectively, in the crayfish central nervous system.     

A quantitative study of command elements for abdominal positioning behavior in the crayfish Procambarus clarkii

We develop a statistical method to estimate the total number of command elements devoted to abdominal positioning behavior in crayfish. We assumed that all command elements can be identified, that each identified cell is equivalent to a tagged individual in a population, and that the cells were sampled randomly. Samples of 29, 30, 20, and 35 cells from abdominal ganglia A3, A4, A5, and A6, respectively, were taken from our catalog. We characterized each cell using several morphological and physiological criteria, determined how many times each identified cell was present in the sample, and estimated the total number of command elements using both a maximum likelihood method and a modification of the Lincoln index. The larger the proportion of identified cells seen only once in the sample, the more identified cells there were that were unrepresented in the sample. We estimate there are approximately 34, 60, 86, and 98 command elements in ganglia A3, A4, A5, and A6, respectively. Using a slightly different data set we show that the motor output of unipolar cells is more often stronger in the direction of the cell's axonal projection. In bipolar command elements, the output strength was uncorrelated with the relative sizes of the two projecting axons. No two cells in our sample were completely identical, and this morphological variability sometimes made it difficult to determine whether or not two cells obtained from different individuals were the same identified cell. We discuss why caution should be exercised in studies requiring precision in cell identification.     

The effects of transport stress on tiger physiology and behavior

Tigers are often transported for education, conservation, and zoo enhancement purposes, however the effect of transfer on them has not yet been documented. Our objective was to evaluate how transport affects the behavior and physiology of tigers, taking into account previous experience with the transport procedure. We simulated transport by relocating five tigers in a small individual transfer cage. Two tigers had prior experience with the procedure, and three tigers were naïve to it. After 30 min, each tiger was released back into their original enclosure. Physiological measurements were recorded for four of the five tigers; these included respiration rate and immune‐reactive fecal cortisol response using radioimmunoassay. We also recorded the behavior of all five tigers before, during, and after transport. Our behavioral analysis included activity level, pacing behavior, time spent investigating, respiration rate, and ear position. Average respiration rates of all tigers increased from 56.1 breaths/min to 94.6 breaths/min during transport and to 132.3 breaths/min 10 min following release into their enclosures. Average immune‐reactive cortisol concentrations peaked 3–6 days after transport at 239% above baseline and returned to baseline levels 9–12 days afterward. During their peak time block, naïve tigers exhibited a higher average increase in cortisol levels (482% above baseline) than the experienced tigers (158% above baseline). The naïve tigers' average immune‐reactive cortisol concentration remained elevated for a longer period (9–12 days) than the experienced tigers' (3–6 days). In both groups, behavioral responses ranged from active to inactive, however naïve tigers performed these repertoires with greater intensity by pacing faster and performing fewer state changes. Results suggest that prior exposure to elements of the transport procedure may lead to some level of habituation, thus reducing the effects of transportation stress. Zoo Biol 23:335–346, 2004. © 2004 Wiley‐Liss, Inc.     

Contrasting effects of an invasive crayfish (Procambarus clarkii) on two temperate stream communities

1. The effects of omnivorous exotic species on native communities are often difficult to predict because of the broad diets and behavioural flexibility of the omnivore, and the diverse abiotic and biotic characteristics of invaded systems. We investigated experimentally the effects of a gradient of density of the introduced, omnivorous red swamp crayfish Procambarus clarkii (Decapoda: Cambaridae) on two stream communities in southern California, U.S.A. 2. The Ventura River is a clear, flowing stream with a cobble substratum, with abundant algae but low densities of large invertebrates, small herbivores and snails. The Santa Ynez River at the time of the study consisted of a series of drying pools underlain by sand, with abundant charophytes, large predatory invertebrates and herbivores, including snails. 3. In the Ventura River, periphyton biomass and inorganic sediment decreased with increasing crayfish abundance, but in the Santa Ynez River, periphyton and sediment were unrelated to crayfish densities. 4. In the Ventura River, the biomass and density of all benthic invertebrates combined, chironomids, micropredators, the meiofauna (chydorid cladocerans, copepods and ostracods), and specific predatory and herbivorous taxa, as well as taxon richness, were negatively related to crayfish density. In the Santa Ynez River, the biomass and average body size of benthic invertebrates, predatory invertebrates, herbivores and chironomids, but not total invertebrate density or taxon richness, were negatively related to crayfish density. 5. Fewer large predatory invertebrates and snails (Physella gyrina) in both streams, and baetid mayflies in the Ventura River, were visible at night in channels where crayfish were abundant. Snails responded to crayfish by moving above the water line in the Santa Ynez River, but not in the Ventura River. 6. We suggest that the same omnivore had different effects on these neighbouring streams because of crayfish predation on large invertebrates in the Santa Ynez River and the scarcity of such prey in the Ventura River, leading to increased crayfish grazing on periphyton, and reductions in periphyton‐associated invertebrates, in the Ventura River.     

Biochemical and proteomic effects in Procambarus clarkii after chlorpyrifos or carbaryl exposure under sublethal conditions

In vivo effects of two sublethal doses of chlorpyrifos and carbaryl were studied in Procambarus clarkii after 2 and 7 days of exposure, and after pesticide removal. Chlorpyrifos inhibited carboxylesterase activity in a concentration-dependent manner, but acetylcholinesterase was less sensitive. Compared with chlorpyrifos, carbaryl had a less marked effect on esterase activity. The effects of selected pesticides on biotransformation or oxidative stress biomarkers were contradictory. Chlorpyrifos lowered ethoxyresorufin-O-deethylase (EROD), catalase and oxidized glutathione (GSSG) levels but raised glutathione-S-transferase activity, while carbaryl raised EROD, catalase and glutathione-S-transferase, but lowered glutathione peroxidase and reduced glutathione (GSH) levels. The effects on protein expression patterns depending on pesticide type and the tissue used for analysis were studied in parallel by 2-DE. In gill and nervous tissue about 2000 spots (pI 4–7) were resolved, with quite different expression patterns. Chlorpyrifos altered 72 proteins, mostly in nervous tissue, and carbaryl 35, distributed evenly between organs. Several specific spots were selected as specific protein expression signatures for chlorpyrifos or carbaryl exposure in gills and nervous tissue, respectively.     

The effects of some putative transmitters and biogenic amines on uropod abductor muscle in the crayfish Procambarus clarkii and Cambaroides japonicus

The effects of some putative transmitters and biogenic amines were examined on the uropod ventral abductor exopodite (AbdExV) muscle in two crayfish species Procambarus clarkii and Cambaroides japonicus. Bath application of L-glutamate to the AbdExV muscle caused sustained contract while gamma-aminobutyric acid (GABA) depressed the nerve-evoked contraction of the muscle. Acetylcholine (ACh) had no effect on both the resting tension and the nerve-evoked contraction. Iontophoresis of L-glutamate and GABA onto the surface of the muscle fiber further confirmed that glutamate and GABA are the possible excitatory and inhibitory transmitters respectively at the neuromuscular junction of AbdExV muscle. Bath application of 5-hydroxytryptamine (5-HT) and octopamine (Oct) caused enhancement of the nerve-evoked contraction but dopamine (DA) had no effect on both the resting tension and the nerve-evoked contraction.     

Experimental modification of stepping course in spontaneously initiated locomotor behavior in the crayfish Procambarus clarkii Girard

The stepping course in spontaneously initiated walking of crayfish was quantitatively analyzed using a spherical treadmill system. In complete darkness, some animals stepped either forward or backward at random whereas others showed individually a consistent tendency of stepping in a specific direction although no external sensory cue was provided. The tendency was statistically significant and invariable for at least 6-8 h. When a light stimulus was present in front of the animal, the stepping course tended to be backward or curved forward to avoid the stimulus. Either in complete darkness or in the presence of a light stimulus, the animal's tendency to step in a specific direction could be modified experimentally by applying electrical stimulation to a part of the animal body upon stepping in the preferred direction. The newly acquired tendency of stepping direction could be retained for 6 h and modified again by a similar procedure of electric stimulation. Both before and after modification of the stepping course tendency, animals seldom changed their stepping direction once the walking was initiated. These findings suggest that the stepping course in spontaneously initiated walking is significantly affected by animal's previous experience and could be predetermined at the onset of walking.     

Elevated carbon dioxide has limited acute effects on Lepomis macrochirus behaviour

The current study investigated the behavioural response of Lepomis macrochirus following exposures to elevated carbon dioxide (CO₂). For this, L. macrochirus were held at ambient pCO₂ (160 μatm pCO₂) for 7 days, then exposed to elevated pCO₂ (8300 μatm pCO₂) for 5 days, and then returned to ambient conditions for a further 5 days to recover. At the end of each exposure period, several behavioural metrics were quantified (boldness, lateralization and activity). Data showed no change in lateralization and most metrics associated with performance and boldness. During the boldness test, however, average velocity, velocity in the thigmotaxis (outer) zone and proportion of activity in the thigmotaxis zone increased with pCO₂ exposure. During post‐exposure, average velocity of L. macrochirus decreased. In addition, individual rank was repeatable during the pre‐exposure and post‐exposure period in three of the 17 metrics investigated (average velocity in the middle zone, average velocity near object and total shuttles to the object zone), but not during the CO₂ exposure period, suggesting that elevated pCO₂ disrupted some behavioural performances. Overall, this study found elevated pCO₂ caused disruption to behaviours of freshwater fishes such as L. macrochirus and effects do not appear to be as serious as has been shown for marine fishes.     

Microinjection of mRNA encoding rat synapsin Ia alters synaptic physiology in identified motoneurons of the crayfish,Procambarus clarkii

Studies of identified neurons have made important contributions to our understanding of cellular neurophysiology. We have developed a technique for modifying gene expression in identified motoneurons of the crayfish Procambarus clarkii in the isolated nervous system as well as in the intact animal through the injection of exogenously synthesized RNAs. mRNA suitable for injection was transcribed in vitro from cDNA templates cloned into a plasmid, pSEM. Initially, mRNAs encoding green fluorescent protein (GFP) and β-galactosidase were injected into the soma of the motor giant neuron (MoG) to determine whether these mRNAs could be successfully translated into protein. Both proteins were expressed. Measurements of GFP fluorescence increase indicated that GFP mRNA was stable and translated into protein for at least 3 days postinjection. We then examined the effects of expression of GFP, AASP-168 (an endogenous crayfish axonal protein), and rat synapsin Ia on MoG synaptic physiology. The mRNA injection procedure did not appear to directly influence synaptic physiology based on the results of the AASP-168 and GFP injections. Injection of mRNA encoding rat synapsin Ia resulted in a significant increase in peak excitatory postsynaptic potential (EPSP) amplitude during repetitive stimulation. These data are consistent with previous studies that have shown that synapsin deficiency reduces synaptic vesicle numbers. The translation of mRNAs with diverse functions and species of origin suggests that this approach will prove useful for studying the function of a wide variety of endogenous and exogenous genes in identified neurons. © 1998 John Wiley & Sons, Inc. J Neurobiol 37: 224–236, 1998     

克氏螯虾虾壳制备氨基葡萄糖盐酸盐的工艺研究

研究了以克氏螯虾壳为原料制备氨基葡萄糖盐酸盐 (GAH)的工艺条件 :酸水解液为 10mol·L-1HCl,85～ 92℃水解 5～ 6h ;甲壳素∶酸水解液为 3∶5。GAH产率为甲壳素的 5 2 %～ 5 5 %。GAH纯度 :99%～ 10 0 .5 %。     

克氏原螯虾(Procambarus clarkii)血细胞染色方法的研究

甲壳类血细胞的形态和分类是甲壳类免疫学研究的基础.本文选择三种甲壳类血细胞的常用染料:瑞氏染液、姬姆萨染液和瑞氏-姬姆萨混合染液,研究它们对于克氏原螯虾血细胞的染色效果.通过改变染色时间、染色温度、分色方式以及分色时间等染色条件,观察、比较不同染色条件下血细胞内的颗粒、细胞核和细胞质的着色情况,以及细胞整体轮廓清晰程度,确定适用于克氏原螯虾血细胞染色的理想染色方法,并建立相应的操作程序.     

仙姑弹琴蛙蝌蚪对陌生捕食者克氏原螯虾的反捕反应

以峨眉山的仙姑弹琴蛙 (Ranadaunchina)蝌蚪作为猎物 ,该地区潜在的入侵物种克氏原螯虾 (Procambarusclarkii)为捕食者 ,于冬季设计实验观察仙姑弹琴蛙蝌蚪对陌生入侵捕食者的反捕行为反应。实验按照 3× 3× 2因子设计 ,即 :捕食者状况 3个水平 (食植物的克氏原螯虾、食蝌蚪的克氏原螯虾和无捕食者 ) ,蝌蚪年龄组 3个水平(31- 35期的 2 .5龄蝌蚪、2 6 - 30期的 1.5龄蝌蚪和 2 5期的 0 .5龄蝌蚪 ) ,以及蝌蚪短期经验 2个水平 (有经验和无经验 )。实验发现 :有短期被捕食经验的蝌蚪的活动时间极显著低于无被捕食经验的蝌蚪 ,而静止时间以及隐蔽所利用时间却极显著地高于无经验的蝌蚪 ;短期经验和捕食者状况的交互效应对蝌蚪的活动时间有显著影响 ;而蝌蚪年龄、捕食者状况及其交互效应对蝌蚪的行为反应没有显著影响。这表明 ,有短期被捕食经历的仙姑弹琴蛙蝌蚪并未通过个体学习建立起对陌生捕食者克氏原螯虾的识别能力 ,而是表现出无针对性的活动性受抑、隐蔽时间增加的行为反应。如果自然条件下的仙姑弹琴蛙蝌蚪也有类似反应 ,在克氏原螯虾入侵初期 ,仙姑弹琴蛙蝌蚪则可能会由于无法识别新的捕食者而表现出过度的反捕行为反应 ,承受更大的亚致死作用 ,而对种群生存造成不利影响     

Behavioral effects of serotonin and serotonin agonists in two crayfish species, Procambarus clarkii and Orconectes rusticus

Exogenous serotonin elicits several behaviors in Procambarus clarkii, including a flexed, elevated posture, reduced locomotion, and changes in aggressive behavior. We conducted experiments to determine if several serotonin agonists mimicked the behavioral effects of serotonin in two crayfish species, P. clarkii and Orconectes rusticus. Drugs tested were 1-(3-Chlorophenyl)-piperazine dihydrochloride (mCPP), Oxymetazoline, 2,5-dimethoxy-4-iodoamphetamine (DOI), CGS-12066A, and (+/-)-8-hydroxy-2-(di-n-dipropylamino) tetralin (8-OH-DPAT). In P. clarkii, mCPP most closely mimicked the effects of serotonin, significantly increasing the performance of the flexed, elevated posture and reducing locomotion; 8-OH-DPAT significantly reduced locomotion as well. Both of these drugs produced significant increases in elevated posture and decreases in locomotion in O. rusticus, and in this species, the drugs at test concentrations were more effective in eliciting these effects than serotonin. The effects of the drugs on behaviors performed during fighting bouts were variable. In both species, only 8-OH-DPAT significantly reduced several agonistic behaviors, and no agonist or 5-HT itself produced significant increases in agonistic behavior.     

Purification and properties of alanine racemase from crayfish Procambarus clarkii

Fresh water crayfish Procambarus clarkii is known to accumulate d-alanine remarkably in muscle after seawater acclimation, accompanied by an increase in alanine racemase activity. We have purified alanine racemase from crayfish muscle to homogeneity. The enzyme is a monomeric protein with a molecular mass of 58 kDa. It is highly specific to alanine and does not racemize l-serine, l-aspartate, l-glutamate, l-valine and l-arginine. The enzyme shows the highest activity at pH 9.0 in the conversion of l- to d-alanine and at pH 8.5 in the reverse conversion. Properties such as amino acid sequence, quaternary structure, pyridoxal 5′-phosphate (PLP)-dependency, pH-dependency and kinetic parameters seem to be distinct from those of the microbial alanine racemases. Various salts including NaCl at concentrations around seawater level were potently inhibitory for the activity in both of l- to -d and d- to -l direction.     

Ontogeny of Cardiac and Ventilatory Function in the Crayfish Procambarus clarkii

SYNOPSIS. Ontog eny of cardiac and ventilatory function wasinvestigated in the direct developing crayfish Procambarus clarkiito determine basic developmental patterns and to evaluate diffusionaland convective gas exchange. Animals were exposed to water rangingin Po₂ from 150 to less than 10 mmHg. Ontogeny of cardiac functionfollows a pattern unlike that observed in other developing organisms.Heart rate (f_H) decreases from the mid-point of embryonic developmentuntil hatching, and the decrease in f_H is accompanied by a concomitantloss in cardiac and ventilatory sensitivity to hypoxia. Duringlarval development however, f_H increases until a juvenile stageis reached. Heart rate then decreases again as the animal increasesin mass. Cardiac and ventilatory responses to hypoxia are restoredby the third larval instar. Ventilatory function is initiatedwithin hours of hatching. Scaphognathite movement (f_sc), whichis initially uncoordinated, does not result in appreciable movementof water, but functional pumping is achieved within hours ofhatching. Animals do not exhibit an adult-like response to hypoxicexposure until at least the third larval instar. The ontogenyof both cardiac and ventilatory function indicates that thedirect developing crayfish is not physiologically mature untilan early juvenile stage. The drop in embryonic JFH and lossof hypoxic sensitivity late in development may indicate thatoxygen requirements of embryos exceed the capacity of egg membranescapacity (surface area) to supply oxygen by diffusion.