Effects of Schistocephalus solidus (Cestoda) on the food intake and diet of the three-spined stickleback, Gasterosteus aculeatus

Seasonal differences were detected between uninfected sticklebacks and those infected with Schistocephalus solidus in their stomach fullness and diet composition.     

尾鳍缺失和恢复生长对不同生境的两种鲤科鱼类快速启动游泳能力的影响

为了考查尾鳍切除及其恢复生长对偏好静水环境的鲫鱼(Carassius auratus)与偏好激流环境的宽鳍鱲(Zacco platypus)两种鲤科鱼类快速启动游泳能力的影响,将鲫鱼幼鱼((6.34±0.02)cm)和宽鳍鱲幼鱼((6.26±0.12)cm)各16尾,其中8尾在(25.0±0.5)℃的条件下分别进行尾鳍切除、20 d恢复生长、再次切除处理,另外8尾作为对照组;测量计算两种实验鱼的相关形态参数并采用电刺激方式,通过高速摄像机获取实验鱼的影像资料,分析计算后获得快速启动相关参数。结果显示:鲫鱼的细度比(FR)显著小于宽鳍鱲(P0.01),尾鳍指数(FI)却显著大于宽鳍鱲(P0.01),两种实验鱼的快速启动最大线速度(Vmax)、移动距离(d)、相对旋转半径(RTr)和弯曲指数(BC)均无显著差异;尾鳍切除后,两种实验鱼快速启动的Vmax、d和RTr与正常组相比均呈现显著下降(P0.01),其中鲫鱼Vmax下降39%而宽鳍鱲下降24%;经过20 d的恢复生长,两种实验鱼的尾鳍面积均恢复至切除前的60%,而快速启动的Vmax、d、RTr和BC却与正常组(同样经过20 d生长)无显著差异;尾鳍再次切除后与正常组相比,鲫鱼和宽鳍鱲Vmax的下降幅度(17%和9%)与首次切除后的(39%和24%)相比均呈现降低的趋势,其中鲫鱼的下降幅度更大;尾鳍再次切除后与正常组相比,宽鳍鱲的BC显著增大(P=0.046)。结果表明:(1)鲫鱼尾鳍对快速启动能力的作用大于宽鳍鱲;(2)而偏好急流环境的宽鳍鱲经过恢复生长表现出更加明显的功能补偿现象。     

温度和重复测定对秦岭细鳞鲑快速启动反应、游泳性能及力竭后代谢特征的影响

在全球气候变暖背景下,冷水性鱼类的温度适应性备受关注。秦岭细鳞鲑(Brachymystax lenok tsinlingensis)是目前世界上分布最南端的两种鲑科鱼类之一,为国家Ⅱ级重点保护水生野生动物。尽管温度是决定该物种生存与分布的关键因子,然而其热生物学相关研究至今鲜见报道。研究考察了驯化温度(6℃、12℃和18℃)和重复测定对秦岭细鳞鲑生态相关的重要指标如快速启动反应、游泳性能及力竭后代谢特征的影响。结果发现:(1)快速启动反应时滞(Latency time,Tlatency)随温度升高而变短(P<0.05),但温度和重复测定对反应率(Reaction rate,R)无显著影响(P>0.05);(2)温度对步法转换速度(Gait transition speed,Ugait)和匀加速游泳速度(Constant acceleration test speed,Ucat)影响显著(P<0.05),重复测定对Ugait和Ucat无显著影响(P>0.05);(3)温度对日常代谢率(Routine metabolic rate, RMR)和最大代谢率(Maximum metabolic rate, MMR)影响显著(P<0.05)、对代谢空间(Metabolic scope,MS)无显著影响(P>0.05),重复测定对MMR和MS均无显著影响(P>0.05);(4)低温驯化方向(6—12℃)生理参数的Q10值较大,而高温驯化方向(12—18℃)生理参数的Q10值较小。研究结果提示:(1)高温下秦岭细鳞鲑快速启动反应更为迅速,但该物种对低强度机械刺激主要采用静息而非逃逸的策略;(2)秦岭细鳞鲑游泳性能对温度变化的敏感性较高,游泳性能的最适温度估计介于12—18℃之间;(3)秦岭细鳞鲑具备较好的代谢恢复与重复运动能力,但总体上游泳性能较弱,可能易受生境水温和水流环境变化的限制。     

Infectivity of plerocercoids of Schistocephalus solidus (Cestoda: Ligulidae) and fecundity of the adults in an experimental definitive host, Gallus gallus.

Aspects of the infectivity of the plerocercoid stage and the fecundity of the adult stage of Schistocephalus solidus were examined using the chicken, Gallus gallus, as an experimental host. To investigate size-related infectivity of the plerocercoid stage to a definitive host, a range of plerocercoids (166) were weighed, and each was fed to an individual male chicken. Only a very small percentage of plerocercoids weighing less than 50 mg established compared with in excess of 50% in all other weight classes. To examine the factors affecting the quantity of eggs produced by the adult stage, 15 similar-sized plerocercoids (160-218 mg) were fed to chickens. The majority of plerocercoids administered established as adults and survived until the experiment was terminated on day 7 postinfection (PI). Fecal egg counts indicated that all established worms commenced egg production on day 2 PI with peak output on day 2 or 3 PI. By day 7 PI, egg production in the surviving worms had declined, but it was still evident. The final weight of the adult and the average egg output per worm were unrelated to the initial weight of the infecting plerocercoid. However, the average egg output was predicted by the final adult dry weight and to a lesser extent by the proportion of weight lost in the transition from plerocercoid to adult, but not by the absolute weight loss.     

The effects of parasitism by the plerocercoid of Schistocephalus solidus Muller 1776 (Pseudophyllidea) on the respiration of the three-spined stickleback Gasterosteus aculeatus L.

Rates of oxygen consumption by parasitized and unparasitized sticklebacks were recorded at three levels of activity in February and August. Negative correlations were demonstrated between specific respiratory rates and fish body weights. At routine and maximum activity, infected fish consumed more oxygen than uninfected fish. At minimum activity levels no significant differences in respiration rates were detected. Seasonal variation in respiration rates was attributed to acclimation. Difficulties of determining specific respiration rates for parasitized organisms are discussed and attempts are made to assess the physiological basis of the respiratory and behavioural characteristics of infected fish.     

不同适应条件对细鳞鲑幼鱼游泳能力的影响

为了研究适应条件对鲑科鱼类幼鱼续航游泳能力的影响,在(16.0±0.2)℃和8 mg/L溶解氧条件下,以续航时间作为评定游泳能力的关键指标,通过适应时间、适应流速、加速时间以及测试流速对细鳞鲑幼鱼的续航游泳时间的影响进行了研究,试验采用4因素8水平的均匀设计方案。结果表明,最大适应流速应控制在1—1.5 BL/s为宜,相应的最佳适应时间应为1 h,在合理条件下适应流速和适应时间对续航游泳能力的影响可忽略不计;加速时间只在大流速条件下(0.5 m/s)对续航时间有极显著影响,其他情况的影响可以忽略不计;尽管长时间适应环境更有利于鱼类身体机能的充分调整,但适应时间仍建议控制在1—2 h以内,且受试鱼类要经过试验前的适应能力筛选;测试流速建议控制在3—4 BL/s以内,以避免超过鱼类的最大游泳耐受范围。测试流速对细鳞鲑幼鱼的续航时间有极为显著的影响,其续航时间随测试流速的增加呈幂函数规律衰减。     

Intestinal parasites of sympatric Pan troglodytes and Papio Spp. at two sites: Gombe (Tanzania) and Mt. Assirik (Senegal)

Experimental and clinical parasitology need natural baselines or “controls”. We present normative data intestinal parasite loads in two genera of African primates. Wild Pan troglodytes and Papio spp. were studied at two sites: Gombe in Tanzania (P. anubis) and Mt. Assirik in Senegal (P. papio). Presence or absence of parasites, especially nematodes, was recorded from fecal specimens. Gombe's primates were more often infected than were Mt. Assirik's. At Gombe, but not at Mt. Assirik, chimpanzees seemed to have a higher incidence of infection than baboons. Comparison of three baboon troops yielded apparent differences in prevalence of infection. No differences in infection were found between the wet and dry seasons in Mt. Assirik's chimpanzees.     

Redescription of Petasiger exaeretus Dietz, 1909 and P. phalacrocoracis (Yamaguti, 1939) (Trematoda: Echinostomatidae), parasites of cormorants

Two echinostome trematodes of the genus Petasiger, P. exaeretus Dietz, 1909 and P. phalacrocoracis (Yamaguti, 1939), parasitising cormorants (Phalacrocoracidae), were found in Phalacrocorax carbo L. from the Czech Republic. Both taxa are redescribed and literary data on their occurence in cormorants are reviewed. The species P. exaeretus appears to be a rather rare species, hitherto recorded in Phalacrocorax carbo in Europe, Kirghizia and Azerbaidzhan. P. baschkirovi Ablassov & Iksanov, 1959 is synonymized with P. exaeretus. P. phalacrocoracis (syn. P. hospitale (Mendheim, 1940) and P. exaeretus auct. nec Dietz, 1909), which has previously been misidentified and erroneously designated as P. exaeretus, appears to be the commonest species of the genus, parasitising cormorants in the Palaearctic Region (Europe, CIS [USSR], Japan) and in Australia. Differential diagnoses of both the above mentioned species are presented.     

Genetic and morphometric variation in the Holarctic helminth parasite Andrya arctica (Cestoda, Anoplocephalidae) in relation to the divergence of its lemming hosts (Dicrostonyx spp.)

Andrya arctica is a cestode parasite of the family Anoplocephalidae (Cyclophyllidea), parasitizing lemmings of the genus Dicrostonyx throughout the Holarctic region. The population structure of this intestinal parasite was studied from eight different regions, six of which represented different genetic entities of lemming hosts. Molecular sequence tagged site markers and minisatellite fingerprints as well as morphology and morphometries were used to reveal the population structure of A. arctica in the Holarctic region. The results suggest that the evolutionary history of this cestode species has included different processes acting on different geographical regions. On the Siberian mainland (host D. torquatus), the division of the parasites into different genetic entities agreed perfectly with the chromosomal races of the lemming hosts that points towards a shared evolutionary history between the host and the parasite ('cospeciation'). The main phylogenetic split of Dicrostonyx between Eurasia and North America was not, however, observed in A. arctica. This suggests that in the Nearctic (host D. groenlandicus) the parasite has remained relatively unmodified because of the large cohesive populations ('coadaptation'). The uniqueness of the Greenland population, and possibly also that of the Wrangel Island, can be explained by peripheral isolation, refugial effects or founder effects.     

Observations on the occurrence of Diplostomum spathaceum and Schistocephalus sp. in ninespine sticklebacks (Pungitius pungitius) from the Belcher Islands, Northwest Territories, Canada

All 175 ninespine sticklebacks, Pungitius pungitius (Linné), collected from the Belcher Islands were parasitized by Diplostomum spathaceum (Rudolphi) and 43% by Schistocephalus sp. D. spathaceum metacercariae were mostly confined to a dorso-ventral band encircling the lens of the eye, and were concentrated in the anterio-dorsal sector of this band. The central area of the lens was thus relatively free of diplostomula, probably minimizing interference with the vision of the fish. The frequency distribution of D. spathaceum abundance in P. pungitius was closely approximated by a negative binomial, while that for Schistocephalus was best fitted by a Poisson. None of the fish condition factors examined appeared related to the intensity of the parasitic infections.     

The morphology and systematic status of Khawia rossittensis (Szidat, 1937) and K. parva (Zmeev, 1936) (Cestoda: Caryophyllidea), parasites of cyprinid fishes

The morphology of the two little-known fish cestodes of the genus Khawia Hsü, 1935, K. rossittensis (Szidat, 1937) and K. parva (Zmeev, 1936) from cyprinid fishes, were studied on the basis of newly collected specimens from goldfish Carassius auratus auratus (L.) and museum specimens, respectively. This paper provides the first detailed species diagnosis for K. rossittensis from Slovakia, which is compared with specimens from different geographical regions and K. parva, a somewhat similar Far Eastern species from the same host. The two species differ in scolex morphology, anterior extent of the vitelline follicles, shape of the ovary and size of the eggs. Based on these differences, K. rossittensis and K. parva are considered to be separate taxa. K. parva, listed among the "species incertae sedis" by Mackiewicz (1972) and even within Caryophyllaeus Gmelin, 1790 by Schmidt (1986), should be considered a valid species of Khawia. The results support the previous conclusions of Kulakovskaya (1961), Dubinina (1971) and Protasova et al. (1990).     

The role of innate and acquired resistance in two natural populations of guppies (Poecilia reticulata) infected with the ectoparasite Gyrodactylus turnbulli

Resource availability, predation, and sexual selection have all been shown to play an important role in the ecology and evolution of guppies, Poecilia reticulata , but the role of parasitism has received comparatively little attention. In the present study, we examined natural infection levels of wild-caught guppies from the Upper and Lower Aripo River in Trinidad (UA and LA, respectively) and experimentally infected a subsample of fish with an isogenic line of the ectoparasite Gyrodactylus turnbulli . LA fish showed a superior resistance compared to UA guppies during the primary, but not secondary infection 53 days later. Resistance of LA individuals was consistent across experiments, suggesting immunocompetence has a heritable genetic basis. The efficiency of the immune response of UA fish was not correlated across infections. During primary infections, UA fish were highly susceptible, but their resistance was significantly improved during a secondary infection, highlighting the importance of acquired resistance. We discuss the role of innate and acquired resistance, and place our findings in the context of natural gyrodactylid infections. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 647–655.     

Molecular phylogeny of Pacific Archigregarines (Apicomplexa), including descriptions of Veloxidium leptosynaptae n. gen., n. sp., from the sea cucumber Leptosynapta clarki (Echinodermata), and two new species of Selenidium

Although archigregarines are poorly understood intestinal parasites of marine invertebrates, they are critical for understanding the earliest stages in the evolution of the Apicomplexa. Previous studies suggest that archigregarines are a paraphyletic stem group from which other lineages of gregarines, and possibly all other groups of apicomplexans, evolved. However, substantiating this inference is difficult because molecular phylogenetic data from archigregarines, in particular, and other gregarines, in general, are severely limited. In an attempt to help fill gaps in our knowledge of archigregarine diversity and phylogeny, we set out to discover and characterize novel lineages of archigregarines with high-resolution light and scanning electron microscopy and analyses of small subunit (SSU) rDNA sequences derived from single-cell (SC) PCR techniques. Here, we describe two novel species of Selenidium, namely Selenidium idanthyrsae n. sp. and S. boccardiellae n. sp., and demonstrate the surface morphology and molecular phylogenetic position of the previously reported species S. cf. mesnili. We also describe a novel genus of archigregarine, Veloxidium leptosynaptae n. gen., n. sp., which branches with an environmental sequence and, together, forms the nearest sister lineage to a diverse clade of marine eugregarines (i.e. lecudinids and urosporids). This molecular phylogenetic result is consistent with the hypothesis that archigregarines are deeply paraphyletic within apicomplexans, and suggests that convergent evolution played an important role in shaping the diversity of eugregarine trophozoites.     

The fecundity, development and host relationships of Ceratobaeus spp. (Hymenoptera: Scelionidae), parasites of spider eggs

Abstract. 1. Ceratobaeus spp. enter the nest of their host spider and oviposit into eggs through the thin silk eggsac.
2. Temperatures below 15° C limit oviposition by slowing parasites down.
3. Males emerge prior to females and mate with their sibs. Sex ratios of 6.6–6.0:1 in favour of females were observed in the field and laboratory for two species.
4. Even though females can oviposit almost immediately after emergence their full complement of eggs (= 65) is not reached until several days later.
5. Superparasitism is low and appears to occur from subsequent accidental ovipositions. No marking of the external surface of hosts was observed.
6. Parasites overwinter as adults under bark. They do not feed as adults nor do they reabsorb their eggs, but rather oviposit as soon as host eggs become available in spring.
7. Successful oviposition occurs in later stages of host eggs reared at 15° C and 20° C than it does at 25°C. Different rates of development between host and parasite is proposed as an explanation for this phenomenon.
8. The species studied show varying degrees of specificity but each has a dominant host. Location of hosts involves cues from the habitat (bark), silk nests of spiders, and some factor associated with host eggs.     

Effects of Benzo(a)pyrene on Seabass (Dicentrarchus labrax L.): Biomarkers,Growth and Behavior

The main purpose of this study was to investigate the effects of benzo(a)pyrene (BaP) on seabass (Dicentrarchus labrax) juveniles using parameters at different levels of biological organization. Liver antioxidant status, BaP biotransformation and accumulation, growth, and behavior were determined in juveniles after 28 d exposure to BaP (1–16 μ g/l). Liver ethoxyresorufin O-deethylase increased in seabass exposed to 1–8 μ g/l of BaP. Liver glutathione S-transferases and catalase activities were significantly increased at 4 and 8 μ g/l, but a slight decrease was observed at the highest concentrations tested. Bile BaP metabolites were significantly different from the control group at 1 and 16 μ g/l BaP. Liver BaP metabolites and lipid peroxidation significantly increased at 8 and 16 μ g/l BaP. These results suggest that BaP metabolites' accumulation induces oxidative damage in seabass liver. Body weight and length increase were significantly reduced in fish exposed to BaP, with LOECs of 16 and 4 μ g/l, respectively. Food intake and swimming velocity were significantly decreased after exposure to BaP, with LOEC values of 16 and 8 μ g/l, respectively. Results suggest that at concentrations of BaP equal or higher than 8 μ g/l, the detoxification capacity decreases, an accumulation of liver BaP metabolites occurs causing lipid peroxidation, affecting growth and swimming capability of fish.     

High levels of metacercarial infestation (family: Diplostomidae) do not affect host energetics and swimming performance in the Epaulette goby (Coryogalops sordidus,Gobiidae)

Parasites have deleterious effects on their hosts, often resulting in altered host behavior or increased energy expenditure. When organisms are exposed to suboptimal environments, parasite loading may increase. Microbialite pools along the warm temperate South African coastline have been hypothesized as refugia for Epaulette gobies (Coryogalops sordidus, Gobiidae) when they are outside of their previously known subtropical distribution. The aim of this study was to determine if C. sordidus individuals infected with metacercarial cysts display higher metabolic rates or different swimming behavior compared to noninfected individuals. We measured each goby's swimming performance using a critical station-holding speed (U_crit) test (n = 60) and visually scored their swimming behavior (n = 52) during these measurements. Also, we measured the metabolic rate of gobies using an intermittent flow respirometer system to determine standard metabolic rate (SMR) and maximum metabolic rate (MMR) from gobies at 21°C before and after swimming trials. Metacercarial load carried by infected gobies seemingly had no impact on the host's energetics (SMR or MMR), swimming ability (as repeated U_crit tests), or swimming behavior compared to noninfected gobies. Thus, the metacercarial intensity observed in gobies in the current study appeared to have no impact on host swimming performance or behavior. Furthermore, the swimming capacity observed for C. sordidus, in general, suggests that this goby is a poor swimmer compared to other gobiid species.     

Molecular Phylogeny and Surface Morphology of Marine Archigregarines (Apicomplexa), Selenidium spp., Filipodium phascolosomae n. sp., and Platyproteum n. g. and comb. from North-Eastern Pacific Peanut Worms (Sipuncula)

ABSTRACT. The trophozoites of two novel archigregarines, Selenidium pisinnus n. sp. and Filipodium phascolosomae n. sp., were described from the sipunculid Phascolosoma agassizii . The trophozoites of S. pisinnus n. sp. were relatively small (64–100 μm long and 9–25 μm wide), had rounded ends, and had about 21 epicytic folds per side. The trophozoites of F. phascolosomae n. sp. were highly irregular in shape and possessed hair-like surface projections. The trophozoites of this species were 85–142 μm long and 40–72 μm wide and possessed a distinct longitudinal ridge that extended from the mucron to the posterior end of the cell. In addition to the small subunit (SSU) rDNA sequences of these two species, we also characterized the surface morphology and SSU rDNA sequence of Selenidium orientale , isolated from the sipunculid Themiste pyroides . Molecular phylogenetic analyses demonstrated that S. pisinnus n. sp. and S. orientale formed a strongly supported clade within other Selenidium and archigregarine-like environmental sequences. Filipodium phascolosomae n. sp. formed the nearest sister lineage to the dynamic, tape-like gregarine Selenidium vivax . Overall, these data enabled us to reassess the molecular systematics of archigregarines within sipunculid hosts and make the following revisions: (1) Filipodium was transferred from the Lecudinidae (eugregarines) to the Selenidiidae (archigregarines), and (2) Platyproteum n. g. was established for Platyproteum vivax n. comb. (ex. S. vivax ) in order to account for the highly divergent morphological features and better resolved phylogenetic position of this lineage.