Quality of capture fishery and aquaculture production statistics for Asia and the Pacific

A review is made of the FISHSTAT NS1 total production statistics and the FISHSTAT AQ aquaculture production statistics for Asia and the Pacific, reported to the FAO. An examination is also made of the quality of these statistics, identifying problems and providing recommendations for possible remedies

Experiences and case studies in the implementation of data collection methods for artisanal fisheries

Details are given of experience gained during the design and implementation of data collection methods for artisanal fisheries in a number of countries under the FAO Technical Cooperation Programme, and other national and regional projects supported by UNDP and Government Cooperation Agencies. Some general approaches that have been introduced in a number of FAO member countries are illustrated and major constraints and problems that are found to be common in the design and implementation of statistical developmental activities are highlighted. It is concluded that statistically-related management tasks are performed more effectively if designated to a national fishery statistical committee or work group with responsibilities and modus operandi as regards system design, development, implementation maintenance and support. Prior to implementing a large-scale system at national level it would be advantageous to develop a prototype system in a geographically limited but representative area. Based on experiences gained from the prototype system, stepwise expansion of the system in other areas may be necessary, by first considering new methodological requirements and operational/logistical constraints

Guidelines for the collection of fishery data for artisanal fisheries

An overview is provided of basic methodological and operational concepts of the statistical monitoring of artisanal fisheries, making specific reference to shore-based sampling surveys. The common characteristics of data collection methods are described and standard procedures for the derivation of estimates from sample magnitudes are discussed. Commonly used approaches for the storage/processing of collected basic data are outlined

The role of fishery co-operatives in coastal fisheries management

Community based approaches to management of coastal fisheries through fishery co-operatives may offer important opportunities. This is shown in the successes achieved in Japan and other countries. In order to play their role, fishery co-operatives need to be socially and economically successful. This inevitable means that they must have been initiated by the fishing communities themselves, the individual fishermen. They need to see the long term benefits of fishery co-operatives and feel the need to join forces. It is a natural step from development of the fisheries and fishery communities to the management of the fisheries. Governments must decentralize the authority over coastal marine areas and initiate programs to provide fishing communities with authority over adjacent resources. Involving fishery co-operatives in management may not be a quick or easy way to success, but it may well be the most effective way

Thyroid hormone deiodination

The enzymatic deiodination of thyroid hormone is an important process since it concerns- among other things- the regulation of thyromimetic activity at the site of the target organ. To understand the mechanism of this regulation it is necessary to have a detailed knowledge of the mode of action of the enzyme(s) involved in the metabolism of thyroid hormone. My investigations of the deiodination of iodothyronines at the subcellular level, forming the basis of this thesis, are described in the appendix papers. It is not intended to deal in extenso with the technical aspects of my studies in the preceeding chapters. Rather it will be attempted to give a general review of the literature including- with some emphasis -my own work. Though not directly related to the subject of this thesis, the biosynthesis of thyroid hormone in the thyroid gland is treated in the first chapter. This is done because of possible similarities between thyroid hormone iodination and deiodination pathways, which are suggested by the finding that some drugs inhibit both processes. In the same chapter the relationship between iodothyronine structure and biological potency is described to illustrate that indeed deiodination has a dramatic effect on the activity of thyroid hormone. Besides deiodination, other pathways of metabolism are also considered. The second chapter concerns the in vivo investigation of thyroid hormone deiodination under physiological and pathological conditions. This includes the effects of internal and external factors which affect deiodination, such as dietary intake, drugs, stress and illness. Since much work has been done to find an explanation for the effect of calorie restriction on deiodination at the molecular level, the role of the diet is emphasized. This appears particularly important since nutritional status must be considered to contribute to the change in thyroid hormone metabolism found in other situations, for example in systemic illness. The in vitro observations of the enzymatic deiodination of thyroid hormone are described in chapter 3. A distinction has been made between (early) reports on the analysis of iodide production using chromatography, and (more recent) studies dealing with the detection of specific metabolites, often by means of radioimmunoassay. My investigations which belong to the latter category are presented in the appendix paper

Substitution of cysteine for selenocysteine in the catalytic center of type III iodothyronine deiodinase reduces catalytic efficiency and alters substrate preference

Human type III iodothyronine deiodinase (D3) catalyzes the conversion of T(4) to rT(3) and of T(3) to 3, 3'-diiodothyronine (T2) by inner-ring deiodination. Like types I and II iodothyronine deiodinases, D3 protein contains selenocysteine (SeC) in the highly conserved core catalytic center at amino acid position 144. To evaluate the contribution of SeC144 to the catalytic properties of D3 enzyme, we generated mutants in which cysteine (D3Cys) or alanine (D3Ala) replaces SeC144 (D3wt). COS cells were transfected with expression vectors encoding D3wt, D3Cys, or D3Ala protein. Kinetic analysis was performed on homogenates with dithiothreitol as reducing cofactor. The Michaelis constant of T(3) was 5-fold higher for D3Cys than for D3wt protein. In contrast, the Michaelis constant of T(4) increased 100-fold. The D3Ala protein was enzymatically inactive. Semiquantitative immunoblotting of homogenates with a D3 antiserum revealed that about 50-fold higher amounts of D3Cys and D3Ala protein are expressed relative to D3wt protein. The relative substrate turnover number of D3Cys is 2-fold reduced for T(3) and 6-fold reduced for T(4) deiodination, compared with D3wt enzyme. Studies in intact COS cells expressing D3wt or D3Cys showed that the D3Cys enzyme is also active under in situ conditions. In conclusion, the SeC residue in the catalytic center of D3 is essential for efficient inner-ring deiodination of T(3) and in particular T(4) at physiological substrate concentrations

Substitution of cysteine for a conserved alanine residue in the catalytic center of type II iodothyronine deiodinase alters interaction with reducing cofactor

Human type II iodothyronine deiodinase (D2) catalyzes the activation of T(4) to T(3). The D2 enzyme, like the type I (D1) and type III (D3) deiodinases, contains a selenocysteine (SeC) residue (residue 133 in D2) in the highly conserved catalytic center. Remarkably, all of the D2 proteins cloned so far have an alanine two residue-amino terminal to the SeC, whereas all D1 and D3 proteins contain a cysteine at this position. A cysteine residue in the catalytic center could assist in enzymatic action by providing a nucleophilic sulfide or by participating in redox reactions with a cofactor or enzyme residues. We have investigated whether D2 mutants with a cysteine (A131C) or serine (A131S) two-residue amino terminal to the SeC are enzymatically active and have characterized these mutants with regard to substrate affinity, reducing cofactor interaction and inhibitor profile. COS cells were transfected with expression vectors encoding wild-type (wt) D2, D2 A131C, or D2 A131S proteins. Kinetic analysis was performed on homogenates with dithiothreitol (DTT) as reducing cofactor. The D2 A131C and A131S mutants displayed similar Michaelis-Menten constant values for T(4) (5 nM) and reverse T(3) (9 nM) as the wt D2 enzyme. The limiting Michaelis-Menten constant for DTT of the D2 A131C enzyme was 3-fold lower than that of the wt D2 enzyme. The wt and mutant D2 enzymes are essentially insensitive to propylthiouracil [concentration inhibiting 50% of activity (IC(50)) > 2 mM] in the presence of 20 mM DTT, but when tested in the presence of 0.2 mM DTT the IC(50) value for propylthiouracil is reduced to about 0.1 mM. During incubations of intact COS cells expressing wt D2, D2 A131C, or D2 A131S, addition of increasing amounts of unlabeled T(4) resulted in the saturation of [(125)I]T(4) deiodination, as reflected in a decrease of [(125)I]T(3) release into the medium. Saturation first appeared at medium T(4) concentrations between 1 and 10 nM. In conclusion: substitution of cysteine for a conserved alanine residue in the catalytic center of the D2 protein does not inactivate the enzyme in vitro and in situ, but rather improves the interaction with the reducing cofactor DTT in vitro