Global introductions of salmon and trout in the genus <Emphasis Type="Italic">Oncorhynchus</Emphasis>: 1870–2007

The purpose of this review is to provide a global perspective on Oncorhynchus salmonine introductions and put-and-take fisheries based on modern stocking programs, with special emphasis on freshwater ecosystems. We survey the global introductions of nine selected salmonines of the genus Oncorhynchus: golden trout, cutthroat trout, pink salmon, chum salmon, coho salmon, masu/cherry salmon, rainbow trout/steelhead, sockeye salmon/kokanee, and chinook salmon. The information is organized on a geographical basis by continent, and then by species and chronology. Two different objectives and associated definitions of ‘success’ for introductions are distinguished: (a) seed introduction: release of individuals with the purpose of creating a wild-reproducing, self-sustaining population; and (b) put-and-take introduction: release of individuals with the purpose of maintaining some level of wild population abundance, regardless of wild reproduction. We identify four major phenomena regarding global salmonine introductions: (1) general inadequacy of documentation regarding introductions; (2) a fundamental disconnect between management actions and ecological consequences of introductions; (3) the importance of global climate change on success of previous and future introductions; and (4) the significance of aquaculture as a key uncertainty in accidental introductions. We conclude this review with a recognition of the need to terminate ongoing stocking programs for introduced salmonines worldwide.     

The development of anoxia following occlusion

Following arteriolar occlusion, tissue oxygen concentration decreases and anoxic tissue eventually develops. Although anoxia first appears in the region most distal to the capillary at the venous end, it eventually spreads throughout the entire region of supply. In this paper the changing oxygen concentration, from the time of occlusion until the tissue is entirely anoxic, is examined mathematically. The equations governing oxygen transport to tissue are solved by iterating a nonlinear integral equation. This solution is valid until anoxia first appears. After anoxia develops it is necessary to solve a moving boundary problem. This is done using the method of matched asymptotic expansions, and accurate solutions are obtained for a wide range of physiological conditions.     

Purification and autophosphorylation of insulin receptors from rat skeletal muscle

Insulin receptors of rat skeletal muscle were purified by first extracting a plasma membrane-enriched pellet obtained from a muscle homogenate with Triton X-100, followed by WGA-Sepharose and insulin-Sepharose affinity chromatography. Routinely, 4-5 micrograms of purified receptor were obtained from 15 g of tissue. The purified receptors are composed of two major polypeptides with molecular weights of 130,000 and 95,000, respectively. The binding of [125I]insulin by the purified receptors was analyzed by a Scatchard plot. There are at least two binding components. The high-affinity component, with an apparent association constant (Ka) of 2.0 X 10(9) M-1, comprises 10% of the total insulin binding sites; while the low-affinity component, with a Ka value of 1.4 X 10(8) M-1, represents 90% of the binding sites. Assuming the insulin receptor to have a molecular weight of 300,000, the receptor binds 1.7 mol of insulin per mol at saturation. Insulin is capable of stimulating the autophosphorylation of the beta-subunit of the muscle insulin receptor (Mr 95,000) by 5-10-fold. The stoichiometry of this phosphorylation reaction was determined as 0.8 phosphate per insulin binding site after a 10 min incubation with 100 nM insulin. In a previous report, I showed that the insulin stimulation of glucose transport in diaphragms from neonatal rats was small, even although the diaphragms had normal levels of insulin receptors and glucose transporters (Wang, C. (1985). Proc. Natl. Acad. Sci. USA 82, 3621-3625). To determine whether or not receptor autophosphorylation might be related to this insensitivity to insulin, the level of receptor phosphorylation was quantitated in diaphragms from rats at different stages of development. Autophosphorylation remains unchanged from birth to 21 days of age, suggesting that the lower insulin-stimulated glucose uptake by diaphragms at early stages of postnatal development as compared to that by diaphragms of older rats, is not due to a difference in receptor kinase.     

Distinguishing Drift and Selection Empirically: “The Great Snail Debate” of the 1950s

Biologists and philosophers have been extremely pessimistic about the possibility of demonstrating random drift in nature, particularly when it comes to distinguishing random drift from natural selection. However, examination of a historical case – Maxime Lamotte’s study of natural populations of the land snail, Cepaea nemoralis in the 1950s – shows that while some pessimism is warranted, it has been overstated. Indeed, by describing a unique signature for drift and showing that this signature obtained in the populations under study, Lamotte was able to make a good case for a significant role for␣drift. It may be difficult to disentangle the causes of drift and selection acting in a population, but it is not (always) impossible.     

Temperature influences the expression of fimbriae and flagella in <Emphasis Type="Italic">Hafnia alvei</Emphasis> strains: an immunofluorescence study

Hafnia alvei, a Gram negative bacillus related to the Enterobacteriaceae family, is considered an opportunistic pathogen of several animal species and humans. In this communication, we describe fimbrial-like structures from different strains of H. alvei that cannot be easily ascribed to any of the previously reported fimbrial types in this species (type I or type III). Polymerase chain reaction (PCR) and immunofluorescence assays were carried out to study fimbriae and flagella in H. alvei strains isolated from different sources. No correlation between the results obtained by PCR and those obtained by phenotypic methods were found, and the antibodies used gave cross or different recognition patterns of the surface structures present in these strains. We report as well that strain and growth temperature influence fimbriation and expression of flagella in human and animal isolates of H. alvei. This study also indicates that the absence of fimbriae have a significant positive influence on the initial adhesion of H. alvei to human epithelial cells.