Ecteinascidia turbinata Extract Activates Components of Inflammatory Responses Throughout the Phylogenetic Spectrum

The tunicate Ecteinascidia turbinata contains a substance orsubstances capable of exerting a number of biological effects.Extracts of tunicate tissues have been shown to kill tumorcells in vitro and arrest tumor growth in vivo. The extractsalso suppress allograft rejection, graft-US.-host reactionsand lymphocyte proliferative responses as well as humoral responsesto immunization. By modifying the conditions, the extracts couldpotentiate antibody responses. In addition, they augment functionsof monocyte-macrophages as evidenced by in vitro phagocytosis,in vivo clearance, and cytotoxic activity against target cells.After studies in mice, we were able to demonstrate that theextracts could activate the phagocytic systems of shrimp, bluecrab, and fish (the American eel). In fish, the intraperitonealroute was superior to the intravenous route for promotion ofphagocytosis, increase in percent presentation of granulocytesand for enhancement of resistance to bacterial infection. Intrarriuscularand intraperitoneal injection led to local inflammation withaccumulation of granulocytes and macrophages.     

Responses to Rapid Temperature Change in Vertebrate Ectotherms

Vertebrate ectotherms often encounter rapid, large scale changesin body temperature. In this paper, I discuss the direct effectsof changing body temperature on physiological parameters, aswell as corrective responses initiated by the animal. For manybiological functions, mean body temperature provides a usefulmeasure of the thermal effects produced by an altered environmentaltemperature. Under most conditions, the fins and body surfaceof fish are more important avenues of heat exchange than thegills. The local thermal sensitivity of peripheral blood vesselsresults in vasomotor adjustments which can alter thermal conductivity.Acid-base balance is challenged by changes in body temperature.Shifts in body temperature also alter metabolic demands, enzymeconformation, ionic and osmotic relationships, spontaneous activitylevels and nervous system function. Compensatory mechanismsinclude behavioral thermoregulation, by which animals seek toavoid stressful thermal environments, and autonomic restorativeresponses such as high temperature panting in reptiles. Waterbreathers may initiate anticipatory responses to minimize arterialoxygen fluctuations during termperature change. The organizationof the central neuronal network underlying the above regulatoryresponses is unclear. Both air and water breathers are ableto initiate compensatory acid-base responses, but the strategiesutilized by the two groups are quite different. Altered bodytemperature initiates long-term acclimation responses, and ifrapid, can also trigger stress responses.     

The influence of large wood on brown trout (Salmo trutta) behaviour and surface foraging

1. Changes in riparian vegetation owing to forest harvesting may affect the input of large wood, a major structural element, to streams. Studies of large wood impacts on stream fish have focused on population‐level responses, whereas little attention has been given to how wood affects fish behaviour. 2. In a laboratory stream experiment, we tested how two size classes of brown trout, Salmo trutta, (mean size of 85 and 125 mm), alone and together, responded to a gradient of large wood in terms of activity, foraging on terrestrial drift and interactions between conspecifics. 3. The results showed that the presence of large wood significantly reduced the overall activity of the fish, the number of agonistic interactions between individuals and the proportion of captured prey. However, activity decreased relatively more than the proportion of captured prey, resulting in a significant positive net effect of wood on the number of prey captures per time spent active (PTA). This indicates that trout living in habitats with high wood density may have a higher net energy gain than trout living in habitats with less wood. 4. There were no observable size‐class differences in the benefits of large wood or in the utilisation of surface‐drifting terrestrial prey. 5. These results suggest that the presence of large wood may be an important factor shaping stream communities and that a lack of structural complexity may decrease energy gain, increase agonistic interactions and, consequently, lower the production of brown trout.     

Kinetics of Expression of Two Major Plasmodium berghei Antigens in the Mosquito Vector, Anopheles stephensi

ABSTRACT. Expression of a 21 kDa determinant (Pbs21), first detected on the surface of ookinetes, and of the circumsporozoite protein (CSP) was studied by immunofluorescence and Western blots during the developmental cycle of Plasmodium berghei in the mosquito A nopheles stephensi . The expression of Pbs21 was predominantly localised on the ookinete surface one day after the infectious blood meal, and thereafter reactivity declined to a minimum on days 2 and 3, the time of onset of oocyst development. A gradual increase in fluorescence was observed on the oocysts from day 6 that was retained until day 17 post-infection. In contrast, sporozoites released from oocysts or salivary glands showed little or no antibody labelling with anti-Pbs21. Circumsporozoite protein was not detectable in any rnidgut preparations until 5–6 days after feeding, when reactivity was observed against immature oocysts. Expression then continued and increased throughout oocyst and sporozoite development. Western blots confirmed that Pbs21 was expressed minimally during the oocyst development but was not detectable in sporozoites. Co-localisation of anti-Pbs21 and anti-CSP monoclonal antibodies to the 50 kDa and 60 kDa bands in Western blots of sporozoite suggests immunological cross-reactivity between the CSP and the anti-21 kDa antibodies.     

Isolation and Characterization of Kinetoplast DNA Networks and Minicircles from Crithidia fasciculata*

SYNOPSIS. Covalently closed kinetoplast DNA networks have been isolated from stationary phase Crithidia fasciculata cells by a technic involving selective pelleting of the networks at a low centrifugal field. Approximately 62% of the kinetoplast DNA of the cell was recovered free of nuclear DNA by simple differential centrifugation. Purified kinetoplast DNA networks were visualized both in the electron microscope and in the light microscope. Closed networks sedimented as a homogeneous band both in neutral and alkaline sucrose, with an s_20w in neutral sucrose of approximately 5 × 10³. Closed monomeric minicircles were isolated from purified networks by mild sonication and band sedimentation in alkaline sucrose. Several physical properties of closed monomeric minicircles were measured. These included molecular weight, buoyant density in CsCl, superhelix density and sedimentation coefficient.