Mass Stranding of Marine Birds Caused by a Surfactant-Producing Red Tide

In November-December 2007 a widespread seabird mortality event occurred in Monterey Bay, California, USA, coincident with a massive red tide caused by the dinoflagellate Akashiwo sanguinea. Affected birds had a slimy yellow-green material on their feathers, which were saturated with water, and they were severely hypothermic. We determined that foam containing surfactant-like proteins, derived from organic matter of the red tide, coated their feathers and neutralized natural water repellency and insulation. No evidence of exposure to petroleum or other oils or biotoxins were found. This is the first documented case of its kind, but previous similar events may have gone undetected. The frequency and amplitude of red tides have increased in Monterey Bay since 2004, suggesting that impacts on wintering marine birds may continue or increase.     

Evidence for a Novel Marine Harmful Algal Bloom: Cyanotoxin (Microcystin) Transfer from Land to Sea Otters

“Super-blooms” of cyanobacteria that produce potent and environmentally persistent biotoxins (microcystins) are an emerging global health issue in freshwater habitats. Monitoring of the marine environment for secondary impacts has been minimal, although microcystin-contaminated freshwater is known to be entering marine ecosystems. Here we confirm deaths of marine mammals from microcystin intoxication and provide evidence implicating land-sea flow with trophic transfer through marine invertebrates as the most likely route of exposure. This hypothesis was evaluated through environmental detection of potential freshwater and marine microcystin sources, sea otter necropsy with biochemical analysis of tissues and evaluation of bioaccumulation of freshwater microcystins by marine invertebrates. Ocean discharge of freshwater microcystins was confirmed for three nutrient-impaired rivers flowing into the Monterey Bay National Marine Sanctuary, and microcystin concentrations up to 2,900 ppm (2.9 million ppb) were detected in a freshwater lake and downstream tributaries to within 1 km of the ocean. Deaths of 21 southern sea otters, a federally listed threatened species, were linked to microcystin intoxication. Finally, farmed and free-living marine clams, mussels and oysters of species that are often consumed by sea otters and humans exhibited significant biomagnification (to 107 times ambient water levels) and slow depuration of freshwater cyanotoxins, suggesting a potentially serious environmental and public health threat that extends from the lowest trophic levels of nutrient-impaired freshwater habitat to apex marine predators. Microcystin-poisoned sea otters were commonly recovered near river mouths and harbors and contaminated marine bivalves were implicated as the most likely source of this potent hepatotoxin for wild otters. This is the first report of deaths of marine mammals due to cyanotoxins and confirms the existence of a novel class of marine “harmful algal bloom” in the Pacific coastal environment; that of hepatotoxic shellfish poisoning (HSP), suggesting that animals and humans are at risk from microcystin poisoning when consuming shellfish harvested at the land-sea interface.     

Isolation of brush border membranes in vesicular form from the intestinal spiral valve of the small dogfish (Scyliorhinus canicula).

A simple, rapid method for the preparation of purified brush border membranes in vesicular form from rabbit kidney proximal tubules has been applied with closely similar results to the intestinal spiral valve of the small dogfish (Scyliorhinus conicula). Since the dogfish belongs to one of the most ancient species of fish, it may be suggested that the method is generally applicable to all species later evolved which possess a brush border membrane at the mucosal surface of the cells of the intestine or kidney.     

Effects of experimentally increased egg production on female body condition and laying dates in the great skua Stercorarius skua

We investigated the effects of increased egg production on body condition as well as on measures of reproductive performance in great skuas, Stercorarius skua, over two subsequent years. We experimentally increased egg production from the normal two to six eggs. Six eggs might also be produced under natural circumstances after repeated clutch loss. After the production of the last egg we measured: (i) body mass, (ii) pectoral muscle, and (iii) haematocrit, total red blood cell count and mean corpuscular volume, as indicators of body condition. We took the same measurements of control females who had produced the normal clutch of two eggs. The measurements were repeated one year after the manipulation, and survival, laying dates, clutch sizes and hatching success were recorded for up to three consecutive years. After producing six eggs, females were lighter, had smaller pectoral muscles and lower haematological values than control females. Hatching success of eggs was significantly reduced. Even one year after the experiment there were still differences in body condition. Annual survival was not affected by the manipulations, although there was an indication that survival costs depended on whether chicks were raised after the increased egg production. While pair bonds and egg sizes were not affected in the post‐experimental year, females started breeding significantly later than in the previous year. Two years after the experiment laying dates had advanced again and were not different from those of control females. This pattern of maintaining survival and egg sizes, but delaying breeding in the post‐experimental year was found for two independent groups of females which had both been subjected to increased egg production. These results present evidence that increased egg production can have long‐term effects on female body condition and aspects of reproduction. However, although present, the costs of extra eggs appear to have been relatively small in the great skua in comparison to the two other bird species for which inter‐annual effects have been reported.     

GABA(A) receptor alpha-subunit proteins in human chronic alcoholics

Antibodies were raised against specific peptides from N-terminal regions of the alpha1 and alpha3 isoforms of the GABA(A) receptor, and used to assess the relative expression of these proteins in the superior frontal and primary motor cortices of 10 control, nine uncomplicated alcoholic and six cirrhotic alcoholic cases were matched for age and post-mortem delay. The regression of expression on post-mortem delay was not statistically significant for either isoform in either region. In both cortical areas, the regression of alpha1 expression on age differed significantly between alcoholic cases, which showed a decrease, and normal controls, which did not. Age had no effect on alpha3 expression. The alpha1 and alpha3 isoforms were found to be expressed differentially across cortical regions and showed a tendency to be expressed differentially across case groups. In cirrhotic alcoholics, alpha1 expression was greater in superior frontal than in motor cortex, whereas this regional difference was not significant in controls or uncomplicated alcoholics. In uncomplicated alcoholics, alpha3 expression was significantly lower in superior frontal than in motor cortex. Expression of alpha1 was significantly different from that of alpha3 in the superior frontal cortex of alcoholics, but not in controls. In motor cortex, there were no significant differences in expression between the isoforms in any case group.     

Changes in survival characteristics of Diplostomum spathaceum cercariae emerged from cadmium-exposed Lymnaea stagnalis

The effect of exposing Lymnaea stagnalis (Gastropoda: Pulmonata), infected with Diplostomum spathaceum (Trematoda: Diplostomatidae), to 100 microg l(-1) cadmium for 7 days on survival characteristics (survival, tail loss, decaudized cercarial life-span) of emerged cercariae was investigated. Exposure of L. stagnalis to cadmium resulted in significantly increased D. spathaceum cercarial survival and an inhibited tail loss compared to controls. The normal parallel relationship which exists over time between decreasing cercarial survival and increasing tail loss in controls was changed in cercariae from cadmium-exposed hosts with an increased proportion of cercarial deaths occurring without tail loss. The decaudized cercarial life-span over the survival period of the cercarial population did not significantly change. However comparisons between individuals decaudized during the initial 24 h time period with those which were decaudized during the final period of cercarial survival showed a significantly altered life span which did not occur in the control population. As a potential indicator of penetration 'fitness' comparisons were also undertaken between control and exposed cercariae decaudized during the initial 24 h time period, which revealed that the decaudized cercarial life-span from the exposed hosts was significantly different from controls. This may have important implications for the ability of cercariae to migrate through the tissues of their target host. The importance and relevance of these results to parasite transmission are discussed.     

Affinity purification of functional receptors for Escherichia coli heat-stable enterotoxin from rat intestine.

Active receptors for Escherichia coli heat-stable enterotoxin (ST) were partially purified by ligand-affinity chromatography. The affinity column was prepared by coupling ST to biotin derivatized with an extended N-hydroxysuccinylated spacer arm prior to binding to monomeric avidin immobilized on agarose. Detergent extracts of rat intestinal mucosa membranes were quantitatively depleted of ST binding activity when chromatographed on this affinity matrix. Biotinylated ST-receptor complexes were eluted from affinity columns with 2 mM biotin and these complexes quantitatively dissociated with bile salts. Using this technique, functional ST receptors were purified maximally about 2000-fold, with about 3% of the total activity in crude extracts recovered in these purified preparations. Analysis of affinity-purified preparations by polyacrylamide gel electrophoresis and silver staining demonstrated a major protein subunit of 74 kDa. Affinity cross-linking of these preparations to 125I-ST demonstrated specific labeling predominantly of the 74-kDa subunit. In addition, lower amounts of labeled ST were incorporated into subunits of 164 and 45 kDa, confirming the heterogeneous nature of ST receptors. Purified receptors bound ST in a concentration-dependent fashion, with an IC50 of 10(-9) M. These studies demonstrate that ligand-affinity chromatography can be employed to purify ST receptors. The availability of purified receptors will facilitate further studies of mechanisms underlying ST-induced intestinal secretion.     

A Conserved Role for Atlastin GTPases in Regulating Lipid Droplet Size

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