Influence of forskolin and carbachol on intestinal absorption of horseradish peroxidase in the goldfish (Carassius auratus)

The transepithelial route for mucosa-to-serosa transport of the tracer macromolecule horseradish peroxidase (HRP; MW 40 kDa) and modulation of this transport by forskolin and carbachol have been studied in vi-tro in stripped goldfish intestinal epithelium mounted in Ussing-type chambers. Uptake and transport have been investigated by measuring the HRP flux from the muco-sal to serosal sides by an enzymatic method and by visualising HRP reaction products in the mucosa with electron-microscopical techniques. Both the cholinergic agonist carbachol (which is thought to increase intracellular Ca²⁺ and activate protein kinase C activity) and forskolin (a direct activator of adenylylcyclase) affect the amount of enzymatically active HRP in the tissue. In control tissue, HRP product is found only within the epithelial cells, the transepithelial flux reaching a constant value of about 1.5 pmoles/cm² per h. Carbachol increases the amount of HRP product in the cells, but has no significant effect on the HRP flux compared with control values. Forskolin decreases the amount of HRP product in the cells; however, in the presence of forskolin, the lateral intercellular spaces become filled with HRP product. HRP is found in the lamina propria and the transepithelial protein flux increases more than 2.5-fold. In the presence of forskolin plus carbachol, the results are no different from the control. It is concluded that carbachol increases the endocytotic uptake of HRP, whereas forskolin inhibits the uptake but increases the paracellular permeability for HRP in goldfish intestine. Received: 10 July 1995 / Accepted: 4 February 1996     

Alternation of Actinosporean and Myxosporean Phases in the Life Cycle of Zschokkella nova (Myxozoa)

ABSTRACT. Experimental evidence has been gathered to show that the life cycle of the myxozoan gallbladder parasite Zschokkella nova Klokacewa, 1914, which infects the fish Carassius carassius , has a complex life cycle with alternation of two hosts (fish and Oligochaeta) and two developmental phases (myxosporean and actinosporean). The gut epithelium of the oligochaete, Tubifex tubifex , exposed experimentally to Z. nova , obtained from C. carassius , became infected with organisms resembling Actinosporea. The spore structure and cube-like network of the interconnected spores is reminiscent of Siedleckiella silesica Janiszewska, 1952, although the spores are very different in size and number of sporoplasm nuclei. The life cycle of Z. nova resembles that of the whirling disease agent Myxosoma cerebralis described by Wolf and Markiw, which also alternates between fish and oligochaete hosts.     

Tyrosinase positive oculocutaneous albinism in the goldfish,Carassius auratus L., an ultrastructural and biochemical study of the eye

Summary Ultrastructural studies, and cytochemical and biochemical determinations of tyrosinase activity were conducted on the pigment epithelium of albino and xanthic goldfish eyes. In eyes of xanthic goldfish, two types of melanosomes are present, spherical and elongated. Melanized melanosomes are absent in the eyes of the albino goldfish, but elongated lamellar premelanosomes are observed. Internal vesicles are present in both melanosome types in the pigment epithelium of the xanthic goldfish but are absent in premelanosomes of the albino. There are also differences in the distribution of lipid droplets, smooth endoplasmic reticulum and Golgi complexes with the latter two being more abundant in the albino. Tyrosinase was not identified cytochemically; however, the enzyme was demonstrated biochemically in the pigment epithelia of both albino and xanthic goldfish. The enzyme is associated with the particulate and soluble fractions of both types of eyes. Particulate albino tyrosinase may be solubilized by triton X-100 treatment. Tyrosinase inhibitors are present in the particulate fractions of both albino and xanthic goldfish eyes. Thus, in the goldfish, ocular albinism appears to be a multiple defect at the molecular and ultrastructural levels.Contribution Number 362, Department of Biology     

Infectivity, growth, development and pathology of Echinostoma caproni (Trematoda) in the golden hamster

Laboratory hamsters (Mesocricetus auratus) were experimentally infected with 75 ± 15 metacercarial cysts of Echinostoma caproni. Worms were recovered from days 7 to 89 post-infection with eight to 90 (average 37) parasites in the small intestine. Worm wet weights averaged 0.85 mg at 10 days, 1.8 mg at 17 days, 3.4 mg at 45 days, and 7.7 mg at 89 days; average dry weights for the identical days were, 0.15, 0.30, 0.70 and 2.2 mg, respectively. The average body area of worms fixed in hot (80°C) alcohol-formalin-acetic acid was 0.21 mm² on day 3, 4.9 mm² on day 10, and 17.7 mm² on day 42. Clinical signs in some hamsters included progressive unthriftiness and watery diarrhea. Gross examination revealed enlarged lymphatic nodules along the length of the small intestine. The histopathological responses of hamsters to the parasite showed erosion of the intestinal villi with lymphocytic infiltration being the primary response; hemorrhagic areas were also observed in the villi.     

Mast cells in goldfish (Carassius auratus) gut: Immunohistochemical characterization

The common goldfish is the most widespread teleosts in the world. Due to its peculiar characteristics, such as the high resistance, easy availability and stabulation, and for its evolutionary characteristics, this fish lends itself to be one of the most used experimental models. This study aimed to characterize the mast cells in the intestine of Carassius auratus using anti-TLR-2, anti-S100, anti-VIP, anti-serotonin (5-HT) and anti-Piscidin antibodies. The intestine of goldfish, like that of all vertebrates, plays an important role in the immunology of the animal. The gut-associated lymphoid tissue GALT is an immune component containing several specific cells such as lymphocytes, macrophages and mast cells. In addition, the presence of goblet cells in the intestinal epithelium strengthens the defence system, secreting many cytokines and chemokines and displaying antibacterial properties. Our results show mast cells labelled with antibodies that are highly conserved between fish and mammals, demonstrating an active role of these cells in the immune response.     

Differential expression of activin βA and βB genes in female allotriploid and diploid red crucian carp Carassius auratus red var

activin β_A and β_B from diploid and allotriploid crucian carp were cloned.The differential expression of activin β_A and β_B genes in female allotriploid and diploid red crucian carp Carassius auratus red var. were studied and found to be expressed in all the tested tissues; particularly, the expression of activin β_A and β_B was elevated in the ovaries of allotriploids and differential expression in pituitaries during the non-breeding season and the breeding season period. The immunohistochemistry indicated that the abnormal triploid ovaries were dominated by small oogonium-like cells with dense signals and that the elevated expression of activin β_A and β_B in the ovaries of allotriploids may be related to allotriploid sterility.     

Relationship between esterase gene frequencies and length in juvenile snapper Chrysophrys auratus Forster

Samples of 0-group snapper Chrysophrys auratus were collected in the Hauraki Gulf of New Zealand in 1979,1980 and 1981. Each fish was measured and the liver examined for an esterase polymorphism. A similar change in allele frequency with length was observed in each year class. In the total data set there is a significant relationship between allele frequency and length. The relationships between allele frequencies and temperature and growth, along with implications for genetic-stock separation studies are discussed.     

Screening of DNA polymorphisms in samples of archived scales from New Zealand snapper

Primers and protocols were developed to screen effciently DNA sequence polymorphism of nuclear and mitochondrial loci in samples of dried archived scales collected over the last 50 years from the New Zealand snapper Pagrus auratus (Sparidae).