The measurement of sperm motility and factors affecting sperm quality in cultured fish

Many, but not all, amphibian populations have been declining on all six continents on which they live. Although habitat destruction, direct application of toxicants, and introduction of predators/competitors are obvious causes of amphibian declines, many amphibians are dying of infectious diseases in relatively pristine habitats on several continents. In this paper, we review the patterns of these disease outbreaks and the characteristics of amphibian immune systems. Hypotheses are presented to explain the apparent susceptibility of amphibians to these pathogens. Natural and man-made factors that can alter amphibian immune responses to pathogens are discussed. Additional research is needed on the biology of the specific pathogens, the pattern of immune responses they elicit, and the nature of environmental stressors that may increase susceptibility to infectious disease.

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Amphibian declines: an immunological perspective.

Preservation of female genetics is currently done primarily by means of oocyte and embryo cryopreservation. The field has seen much progress during its four-decade history, progress driven predominantly by research in humans, cows, and mice. Two basic cryopreservation techniques rule the field--controlled-rate freezing, the first to be developed, and vitrification, which, in recent years, has gained a foothold. While much progress has been achieved in human medicine, the cattle industry, and in laboratory animals, this is far from being the case for most other mammals and even less so for other vertebrates. The major strides and obstacles in human and other vertebrate oocyte and embryo cryopreservation will be reviewed here.

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Current progress in oocyte and embryo cryopreservation by slow freezing and vitrification

It is a great pleasure welcome the second edition of Professor Harborne’s pioneering work on biochemical ecology. This introductory text provides the reader with a clear and fascinating account of ways in which living organisms can become adapted to their environments and to each other at the biochemical level. Adaptations of plants to drought and flooding, to high and low temperatures, to changes in ionic concentrations and to the presence in the soil of potentially toxic levels of natural and synthetic chemicals are all discussed. The roles of secondary plant compounds in attracting pollinators to flowers, in stimulating insects to feed on particular plant species or in deterring them from feeding on others are reviewed. The effects of plant toxins on animals and the biochemical responses that may be elicited in these animals by such toxins are described, as are animal pheromones and defence substances. Hormonal interactions between plants and animals illustrate how sophisticated and complex biochemical interrelationships can become, and a chapter on higher-plant-higher-plant interactions makes it clear that secondary compounds of plants may be weapons of offence as well as defence, one species synthesizing and releasing into the environment a compound capable of inhibiting growth in its rivals. Phytoalexin production by higher plants in response to invasion by fungi and pathotoxin production by invading micro-organisms are discussed in a final chapter on higherplant-lower-plant interactions. I recommend this book without reservation. The previous edition was not only used, but enjoyed, by my students. It appealed to both the chemically and the biologically inclined, and I believe that the new edition is a worthy successor. At f5.80 it is very good value.

Introduction to Ecological Biochemistry

Since the first work of Blaxter in 1953, fish sperm cryopreservation has been attempted on about 30 marine species. The present paper reviews the techniques used and the results published in these species. Particular attention is paid to the handling procedure of sperm before freezing, the problems of semen ageing and semen contamination with urine. The quality of frozen-thawed semen was evaluated using previously standardized biotests, such as a two-step motility activation technique adapted for the different species and fertilization assays using a discriminating insemination technique. Most extenders used in marine fish are saline or sugar solutions. From the investigated cryoprotectants, dimethyl sulphoxide (DMSO) generally leads to the best results. Cooling rates range from 8 °C to 99 °C min-1; the thawing rate is generally high. Compared with freshwater species, a high percentage of spermatozoa survives cryopreservation. Therefore, and because of the simplicity of the techniques, the cryopreservation of marine fish sperm is suited for application in aquaculture.

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Cryopreservation of sperm in marine fish

Cryopreservation of rainbow trout sperm in large volume straws: application to large scale fertilization

Sublethal Damage during Cryopreservation of Rainbow Trout Sperm

Histological aspects of three Pistacia terebinthus galls induced by three different aphids: Paracletus cimiciformis, Forda marginata and Forda formicaria

Tadpoles of Rana perezi were kept for 14 weeks in water containing two sublethal levels of the carbamate insecticide ZZ-Aphox® or the organophosphate Folidol®. Approximate concentrations of their active ingredients were 0.25 and 1 mg/L. Resulting malformations were studied by skeletal analysis and histological and histochemical investigation of the rear limbs of the tadpoles. The pesticides caused the animals to have malformations of the spinal column (scoliosis) and/or limbs (short and thick long bones with the epiphyses grossly twisted). Histochemical study showed differences in the composition of the connective matrix, and microscopic examination of the long bones indicated alterations in the thickness of the uncalcified bone matrix (osteoid) and the presence of abundant vascularised connective tissue in the region of the periosteum. The results confirmed changes in the composition of the connective tissue matrix as the cause of the defects observed in bone formation which are also discussed in relation to vitamin D absorption and calcium homeostasis.

Rafael Álvarez

Papers

Cryopreservation of rainbow trout sperm in large volume straws: application to large scale fertilization

Sublethal Damage during Cryopreservation of Rainbow Trout Sperm

Histological aspects of three Pistacia terebinthus galls induced by three different aphids: Paracletus cimiciformis, Forda marginata and Forda formicaria

Skeletal malformations induced by the insecticides ZZ-Aphox and Folidol during larval development of Rana perezi.

Vitrification of turbot embryos: preliminary assays.