The androgenic glands of the Pacific crayfish, Pacifastacus leniusculus trowbridgii Stimpson, 1859, were studied experimentally and by light and electron microscopy. The androgenic glands proliferate in the spring of the year concurrently with an increase in mitotic activity in the testes. Degeneration of a major portion of the glands occurs in the fall, when spermatogenic activity in the testes is near completion. Cellular development appears to progress from small undifferentiated cells through stages of vacuolization and hypertrophy and terminates with degeneration or lysis. The fine structure of the vacuolated gland cells is indicative of increased metabolic activity and probable hormone secretion. However, experimental manipulation of the glands of P. leniusculus gave no evidence of their presumed endocrine function. A discussion of the similarities of the androgenic glands with other known arthropod endocrine glands is also included.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 109-116). Also available on the World Wide Web.

The impacts of Invasive Non-Native Species (INNS) are well documented, and INNS management is widely considered one of top threats to global biodiversity and ecosystem function. The American signal crayfish, Pacifastacus leniusculus, is a destructive invader of freshwater ecosystems. In Scotland, this species currently has a restricted distribution. Despite the known impacts and high rates of dispersal, little is being done to manage populations that threaten to spread into Scotland's economically important catchments. One barrier to action on the management of signal crayfish is uncertainty over the implementation and efficacy of control methods. Capture-mark-recapture analysis was used to estimate the size- and season-specific capture probabilities of three traditional and two novel mechanical removal methods. By simulating the effect of harvest with these removal methods on a density-independent population model, a range of optimal seasonal combinations of removal methods were derived. Little empirical evidence exists in compensatory density-dependent dynamics in signal crayfish. I found that the probability of an individual cannibalising was affected by its size and also the density of conspecifics around it. I trialled a seasonally optimal combination of removal methods in two populations, manipulating sections of stream with different crayfish removal intensities, and tracked the movements of marked individuals. There was a high rate of dispersal (33%) that was influenced by the quality of the patch it was leaving, dispersing to, and the intensities of removal applied to the stream sections. Crayfish had a greater probability of moving to high density sections with the highest removal treatment. My conclusions suggest that conventional removal efforts (trapping), may fail due to compensatory effects on mortality and dispersal, and that novel approaches such as targeting smaller size classes are required, but only after quantitative predictions and field trials.

University, Diss., 2004--Kiel.

Thesis (M.S.)--Western Washington University, 2007. / Includes bibliographical references (leaves 73-84).

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2005. / Härtill 5 uppsatser.

Crayfish provide a model which is simple, has an easily-accessible cardiovascular system and can be maintained in the laboratory conditions; the model has good utility for water quality assessment and ethophysiological studies. A noninvasive crayfish cardiac and behavioral activities monitoring (NICCBAM) system is discussed in the thesis. The system is inexpensive, has relatively few components and permits long-term continuous simultaneous monitoring of cardiac and behavioral activities of several crayfish. Moreover, compared to other available systems, it provides a novel approach of cardiac activity shape analysis which allows improving monitoring accuracy as well as obtaining additional information on crayfish functional state. The NICCBAM system was evaluated by comparing with the well-known electrocardiography system which demonstrated that cardiac contractions with both approaches were synchronous and that both signal shapes were similar. Experiments on crayfish cardiac activity relative to selected odors and chemicals demonstrated the promising potential of cardiac signal shape analysis, not only for detecting changes in the aquatic environment, but also for their classification.

The study is focused on the evaluation of crayfish physiological reaction on hygienically treated water with chlorine dioxide (ClO2). A patented non-invasive monitoring system was used for observation of crayfish cardiac and locomotor activity. Monitoring was conducted from February to August 2017 under conditions of private commercial enterprise "Pivovar Protivín" in Czech Republic. Adult individuals of signal crayfish, Pacifastacus leniusculus, were kept separately in water-flow aquariums directly after the water treatment device producing ClO2 in concentration from 0.01 to 0.29 mg.l-1. Observed crayfish response to the disinfectant varied among individuals which could be explained by a different functional state and individual reaction on stimuli. Diurnal rhythm of some crayfish was disturbed even at a lower concentrations of chlorine dioxide (0.01-0.2 mg.l-1), while higher concentrations affected all animals. In addition to that, higher levels of chlorine dioxide ( 0.2 mg.l-1) significantly increased mortality. Maximum concentrations (0.2-0.29 mg.l-1) were observed 28 times in total during 202 days of monitoring, which resulted in 25 mortality cases occurred several days after exposure. In average, mortality of crayfish occurred three-four weeks after stocking to the experimental system. Possible lethal concentration of ClO2, which caused animal mortality, is 0.2 mg.l-1. Results suggested that crayfish exposure to ClO2, obviously, negatively affect their physiological processes; however, further studies are needed to examine specific effects of chlorine dioxide on internal organs of crayfish.

Repairing DNA damage is brought about by highly specific proteins that partake in a variety of DNA repair. Two of the most common types of damage are double-strand breaks (DSBs) and interstrand crosslinks. A single DSB or crosslink can potentially kill a cell if it is not repaired~ In human and other vertebrate cells, DSBs are repaired by two different mechanisms. The nonhomologous end-joining pathway can bring together the broken ends and join them, usually with the loss of some nucleotide sequence. A second pathway, homologous recombinational repair (HRR), is equally important. This repair process utilizes the information provided by another DNA molecule to restore damaged DNA. This molecule is usually a sister chromatid arising from DNA replication. This process is essentially error-free, unlike the end-joining process. Some HRR activity is required for proliferating cells to remain viable. The central protein player is RAD51, which with the help of other proteins such as XRCC2, XRCC3, RAD51B, RAD51C, and RAD51D, performs the critical initiating steps of homologous pairing and strand transfer. The proteins encoded by the familial breast cancer genes, brcal and brca2, also play an important role in HRR. My project is concerned with studying proteins that interact with Drosophila melanogaster (XRCC2). Proteins interacting with DmXRCC2 were identified by using a yeast two hybrid system. "Bait fusion protein" (DmXRCC2 linked to GAIA BD) was constructed by Dr. Wrischnik. Tanya Dimetrijevich, a graduate student, used this bait to fish for interacting or "target" proteins. About 50 such proteins were found. I began validating these target proteins with the intention of exploring novel interactions and functions of DmXRCC2. The process of validating proteins interacting with DmXRCC2 yielded two very interesting candidate proteins-CaBPl and FAF. · CaBPl, also called protein disulfide isomerase P5, is an endoplasmic-reticulum calciumbinding protein. FAF belongs to a large family of deubiquitinating enzymes that cleave ubiquitin-protein bonds and play diverse roles in the ubiquitin pathway. One of the implications of such discoveries could be to compare and contrast DmXRCC2 and human XRCC2 in terms of their interactions and functions.

This thesis deals with monitoring the occurrence of crayfish in selected river basins in the western Bohemia, considering the human impact on freshwater ecosystems and his influence on crayfish and other aquatic organisms. The selected river basin territory was Úhlava, Úslava and Otava. In the localities, numerical and species-wise representation of crayfish was monitored by finding data from the Agency for Nature Conservation and Landscape of Czech Republic database. The flow and environment characteristics were also monitored. This thesis focuses on water quality in streams of selected major river basins, Úhlava, Úslava and Otava rivers in the period from 2006 to 2011. Results of the findings show a sympatric occurrence of original species, stone crayfish (Austropotamobius torrentium), noble crayfish (Astacus astacus) and part of the original danube crayfish (Astacus leptodactylus) with invasively spreading species of spiny-cheek crayfish (Orconectes limosus) and signal crayfish (Pacifastacus leniusculus). With respect to this fact, the sensitivity of spiny-cheek crayfish (Orconectes limosus) and signal crayfish (Pacifastacus leniusculus) are evaluated in a form of own test results on acute toxicity. The thesis compared current results of occurrence and the protection of crayfish in the Czech Republic and abroad. The conclusion of this thesis is a proposal of a freshwater biomonitoring system, using the crayfish.