Mitochondrial plasticity in brachiopod (Liothyrella spp.) smooth adductor muscle as a result of season and latitude

Habitat temperature and mitochondrial volume density (Vv_(mt,mf)) are negatively correlated in fishes, while seasonal acclimatization may increase Vv_(mt,mf) or the surface density of the mitochondrial cristae (Sv_(im,mt)). The effect of temperature on invertebrate mitochondria is essentially unknown. A comparison of two articulate brachiopod species, Liothyrella uva collected from Rothera Station, Antarctica in summer 2007, and Liothyrella neozelanica collected from Fiordland, New Zealand in winter 2007 and summer 2008, revealed a higher Vv_(mt,mf) in the Antarctic brachiopod. The Sv_(im,mt) was, however, significantly lower, indicating the Antarctic brachiopods have more, less reactive mitochondria. L. uva, from the colder environment, had larger adductor muscles in both absolute and relative terms than the temperate L. neozelanica. Furthermore, a seasonal comparison (winter vs. summer) in L. neozelanica showed that the absolute and relative size of the adductor increased in winter, Vv_(mt,mf) was unchanged, and Sv_(im,mt) was significantly increased. Thus, seasonal acclimatization to the cold resulted in the same number of more reactive mitochondria. L. neozelanica was clearly able to adapt to seasonal changes using a different mechanism, i.e. primarily through regulation of cristae surface area as opposed to mitochondrial volume density. Furthermore, given the evolutionary age of these living fossils (i.e. approximately 550 million years), this suggests that mitochondrial plasticity has roots extending far back into evolutionary history.     

Water Quality Criteria for European Freshwater Fish

1. For water pollution control purposes, the concentration-addition model for describing the joint effects of mixtures of toxicants on aquatic organisms is appropriate; in this model the contribution of each component in the mixture is expressed as a proportion of the aqueous concentration producing a given response in a given time (e.g. p 96-h LC50).

2. Examination of available data using this model shows that for mixtures of toxicants found in sewage and industrial effluents, the joint acutely-lethal toxicity to fish and other aquatic organisms is close to that predicted, assuming simple addition of the proportional contribution from each toxicant. The observed median value for the joint effect of these toxicants on fish is 0.95 of that predicted, and the corresponding collective value for sewage effluents, river waters, and a few industrial wastes, based on the toxicity of their constituents, is 0.85, while that for pesticides is 1.3.

3. The less-than-predicted effect of commonly-occurring toxicants in some mixtures may be partly attributable to small fractions of their respective LC50 values having a less-than-additional effect. However, recent research has shown that for some organic chemicals which have a common quantitative structure-activity relationship (QSAR), their joint action as determined by acute toxicity is additive at all concentrations.

4. The few (unpublished) data available for the long-term lethal joint effect on fish of toxicants in mixtures suggest that they may be markedly more than additive, a phenomenon that needs confirmation and further investigation.

5. In the few studies on the sub-lethal effects on fish (eg growth), the joint effect of toxicants has been consistently less-than-additive which suggests that as concentrations of toxicants are reduced towards the levels of no effect, their potential for addition is also reduced. There appear to be no marked and consistent differences between the response of different species to mixtures of toxicants.

6. Field studies have shown that reasonably accurate toxicity predictions based on chemical analysis can be made if the waters which are polluted are acutely lethal to fish, and that a fish population of some kind can exist where the median 2 p t LCSOs (rainbow trout) is < 0.2. It is not known whether this condition is equivalent to a C p NOEC of 4.0 (ie the sum of the individual fractions of the NOEC for the species present), or to a NOEC of < 1.0 for each individual toxicant (i.e. fractions of the NOEC are not summed).

7. In general, the joint effect of the common toxicants on lethal and sub-lethal responses of fish is not explained by variations in the uptake of the individual toxicants concerned; this may not apply for those chemicals with a common QSAR, although there is little experimental evidence in this field.

8. There is an immediate need for more empirical studies on the joint effect of mixtures of toxic units of individual components, and the relation between long- and short-term lethal and non-lethal joint effects. This applies to mixtures of commonly occurring toxicants as well as to mixtures of organic chemicals with a common QSAR. The data obtained should be reinforced by studies on the mechanisms of interaction of toxicants. More field studies which relate water quality to the structure and productivity of fish populations are also required, involving direct measurements of fractional toxicity of the river water wherever possible.

9. The concentration-addition model appears to be adequate to describe the joint effect of commonly-occurring constituents of sewage and industrial wastes, and for tentative predictions of the joint effect on fish populations of toxicants present at concentrations higher than the EIFAC recommended values. However, concentrations lower than the EIFAC recommended values may make an increasingly lesser contribution to the toxicity of mixtures of toxicants and there may be a need to adjust the tentative water quality criteria downwards where two or more toxicants are present at concentrations close to these values. For toxicants with a common QSAR, their additive joint action may necessitate the setting of water quality criteriafor this group as a whole and not on the basis of individual compounds. However, too little is known of their precise joint action where the combined concentration produces a sub-lethal response.     

A GROUND WATER RESOURCES STUDY OF A PACIFIC OCEAN ATOLL - TARAWA,GILBERT ISLANDS1

ABSTRACT: The geology and fresh ground water lens development in a typical Pacific atoll are described together with a method for hydrogeological investigation. The fresh water resources of such lenses are investigated using Tarawa as an example. It is shown that simple steady state solutions cannot be realistically applied, and that despite the paucity of hydrogeological data, which is considered typical of such islands, practical nonsteady state solutions allow resource assessments. The susceptability of lens resources to drought conditions is demonstrated.     

Male and female in organizational behavior

The human division of male and female sexes has profound unacknowledged consequences for behavior in organizations. Sex is not simply an individual difference (like eye color), but is an essential part played in life with others. This essay finds sex to be the main organizing principle of human life. Bringing this fact to light, the essay shows how we can begin to understand many perplexing problems of reconciling men and women in organizations today. Copyright © 2002 John Wiley & Sons, Ltd.     

Regional reports or structure plans? Opportunities for strategic planning in England and Wales

The British Government is proposing a new system of single‐tier development plans for England and Wales, with clear implications for the strategic level of planning. This paper considers a proposal by the Committee of Inquiry into Town and Country Planning set up by the Nuffield Foundation, for a revised strategic planning network which includes a ‘local strategy’. The paper considers the lessons to be drawn from the use of regional reports in Scotland since the early 1970s and concludes on a note of caution for the Government's proposals.     

MUNICIPAL AND INDUSTRIAL WATER SUPPLY IN CIUDAD JUAREZ,MEXICO1

Rapid industrialization and population growth in the north Mexican desert city of Ciudad Juarez are placing a serious strain on the city's municipal water resources. Water deliveries and service area have more than doubled over the past decade, and plans for additional expansion are presently being implemented. This expansion is already contributing to water table declines and salinity increases in the Mexican portion of the Heuco Bolson, the sole source of water for the city. Continued mining of the limited fresh water reserves should produce serious water supply problems in the near future. New estimates of future water consumption incorporated into a digital aquifer simulation model indicate that these problems may show up much sooner than was anticipated in previous investigations. The results of this study point to the need to accelerate the gathering of basic data on alternative water resources. The problems faced by Cd. Juarez are illustrative of the kinds of difficulties likely to confront other rapidly developing cities of the arid zone.     

RECREATION AT THE MC CLELLAN-KERR ARKANSAS RIVER NAVIGATION SYSTEM1

ABSTRACT: Recreation has produced substantial employment, incomes, economic development, and migration impacts since completion of the McCle-lan-Kerr Arkansas River Navigation System. These impacts support the influence of navigation, hydropower, flood control, and channel stabilization outputs on regional development. The marked success is not without substantial costs in public resources, including manpower which are devoted to recreational management. Increasing the share of financial resources obtained from recreational users and transfer of management responsibilities to nonfederal agencies, including private concessionaires is recommended.