Age determination and growth of the pollan, Coregonus autumnalis pollan Thompson, of Lough Neagh, Northern Ireland

Scales from Lough Neagh pollan display a large number of checks, making age determination difficult. Sclerite counts showed that an annual check is formed on scales in May and a second accessory check in most young fish in October. The method of ageing from scales was supported by inspection of length-frequency plots and by following the growth of pollan in their first 2 years of life. The body-scale relationship was curvilinear. Back-calculation showed that pollan of both sexes attain a fork length of 29 cm in 5 years (1 ∞=28.9 cm; k = 0.65; l ₀= -0.06 year). There is no evidence that annual growth rates have changed since 1965. Possible environmental causes of scale check formation are discussed.     

Genetics of whitefish and vendace in England and Wales

Proportion of loci polymorphic ( P ) and mean heterozygosity per locus ( H _exp) were P = 0.130 and H _exp= 0.096 for C. albula from the English Lake District and P = 0.217 and H _exp= 0.046 for C. lavaretus from the English Lake District and Llyn Tegid, Wales in 1991–2. Significant deviation from the Hardy-Weinberg model was observed at the superoxide dismutase ( sSOD* ) locus in C. albula from Bassenthwaite Lake. This could have been due to chance, to the Wahlund effect or to selection. Genetic distances between the two species were consistent with their taxonomy and genetic differentiation was much greater for the C. lavaretus populations than for the two geographically close C. albula stocks. Llyn Tegid C. lavaretus showed unique alleles at two loci and conservation of fish in this lake is therefore of great importance. Red Tarn C. lavaretus differed most from other Lake District populations probably due to founder effects from early stocking events and/or from selection due to the high altitude of this lake.     

Myoglobin polymorphism in the pollan (Osteichthyes: Coregoninae).

Three electrophoretically separable phenotypes of heart and lateral line muscle myoglobin were found in the Irish pollan (Coregonus pollan). This polymorphism appears to be under the control of two co-dominant alleles. The allele frequencies were found to be virtually identical in samples from two lakes which have probably been isolated since the close of the last Ice Age. A significant excess of heterozygotes was found in samples from both lakes. This myoglobin polymorphism appears to be balanced, maintained due to heterozygote superiority.     

The food of the pollan, Coregonus autumnalis pollan Thompson, in Lough Neagh, Northern Ireland

Stomach contents of pollan caught monthly throughout the year were examined. Stomach fullness was significantly correlated with water temperature. Adult pollan fed on bottom fauna, mainly chironomid larvae, in October-March, chironomid pupae in April and on Daphnia spp. in May-September. Immature (0+ and 1 +) fish also ate other cladocerans and copepods. While there is no evidence for selection of any benthic prey species, adult pollan appear to be highly selective feeders on Daphnia spp. in summer.     

STUDIES ON THE MONOAMINE OXIDASE OF MONKEY BRAIN

Abstract— A study of the enzyme monoamine oxidase (MAO) was carried out in the monkey brain. From the monkey brain mitochondrial fraction a lysolecithin-soluble form of the enzyme (MAO_s and an insoluble form (MAO_p) were isolated. The latter required freezing, thawing and sonication for solubilization. Both these forms of MAO had identical electrophoretic mobilities, a pH optimum of 7 and comparable thermal stabilities. The enzyme which could not be solubilized and which remained membrane-bound also gave the same pH optimum of 7 and a similar thermal stability profile. Both MAO_s and MAO_p had comparable K _m values of 2.2 × 10⁻⁵ m and 5.0 ×^105- m respectively when using tyramine as substrate and 7.4 ×⁻⁵ M and 7.7 × 10⁻⁵ m respectively with benzylamine as substrate. The K _m values of the membrane-bound enzyme were 1.0 × 10"⁵m with tyramine as substrate 2.5 × m with benzylarnine as substrate. The MAO inhibitors, tranylcypromine, isocarboxazid and iproniazid inhibited both MAO_s and MAO_p to approximately the same extent. The extent of inhibition of the membrane-bound enzyme however, was relatively different with all three inhibitors. Immunodiffu-sion techniques using anti-MAO_p indicated the immunological identity among MAO_p, MAO_s and the mitochondrial fraction. Substrate specificity and substrate competition experiments as well as the use of the selective inhibitor pargyline indicated the presence of both the 'A' and 'B' type of activity in the MAO isolated from monkey brain.     

Myoglobin polymorphism in the pollan (Osteichthyes: Coregoninae)

Three electrophoretically separable phenotypes of heart and lateral line muscle myoglobin were found in the Irish pollan (Coregonus pollan). This polymorphism appears to be under the control of two co-dominant alleles. The allele frequencies were found to be virtually identical in samples from two lakes which have probably been isolated since the close of the last Ice Age. A significant excess of hetero-zygotes was found in samples from both lakes. This myoglobin polymorphism appears to be balanced, maintained due to heterozygote superiority.     

The Irish pollan, Coregonus autumnalis: options for its conservation

The ecology of four relict Irish populations of pollan ( Coregonus autumnalis ) is compared with that of the species elsewhere, and used to advocate conservation. The threats to these populations from introduced/invasive species, habitat degradation, climate warming and commercial exploitation are summarized and the legislation governing conservation of the stocks is reviewed. Conservation options (legislation, habitat restoration, stock translocation and stock augmentation) are outlined and their practicality and efficacy considered. A preliminary search indicates that there are a number of lakes that appear to be suitable for pollan translocation.     

Characterization of two 3-ketothiolases possessing differing substrate specificities in the polyhydroxyalkanoate synthesizing organism Alcaligenes eutrophus

Abstract Two constitutive acetyl-CoA acetyltransferases (3-ketothiolases A and B) were purified from Alcaligenes eutrophus . Enzyme A was active with only acetoacetyl-CoA and 3-ketopentanoyl-CoA, whereas enzyme B was active with all the 3-ketoacyl-CoAs (C₄−C₁₀) tested. Enzyme A appeared to be a tetramer ( M _r 70 000) with identical subunits ( M _r 44 000) and enzyme B had a similar M _r of 168 000 (containing M _r 46 000 subunits). Enzymes A and B had isoelectric points of 5.0 and 6.4, respectively. The stoichiometry of the reactions catalysed by each enzyme was confirmed. K _m values of 44 μM and 394 μM for acetoacetyl-CoA, and 16 μM and 93 μM for CoA, were determined with enzymes A and B, respectively. Enzymes A and B gave K _m values of 1.1 mM and 230 μM, respectively, for acetyl-CoA. The condensation reaction was potently inhibited by CoA in both cases.     

Paramecium Has Two Regulatory Subunits of Cyclic AMP-Dependent Protein Kinase, One Unique to Cilia

ABSTRACT. The subunit composition and intracellular location of the two forms of cAMP-dependent protein kinase of Paramecium cilia were determined using antibodies against the 40-kDa catalytic (C) and 44-kDa regulatory (R₄₄) subunits of the 70-kDa cAMP-dependent protein kinase purified from deciliated cell bodies. Both C and R₄₄ were present in soluble and particulate fractions of cilia and deciliated cells. Crude cilia and a soluble ciliary extract contained a 48-kDa protein (R₄₈) weakly recognized by one of several monoclonal antibodies against R₄₄, but not recognized by an anti-R₄₄ polyclonal serum. Gel-filtration chromatography of a soluble ciliary extract resolved a 220-kDa form containing C and R₄₈ and a 70-kDa form containing C and R₄₄. In the large enzyme, R₄₈ was the only protein to be autophosphorylated under conditions that allow autophosphorylation of R₄₄ The subunits of the large enzyme subsequently were purified to homogeneity by cAMP-agarose chromatography. Both C and R₄₈ were retained by the column and eluted with 1 M NaCl; no other proteins were purified in this step. These results confirm that the ciliary cAMP-dependent protein kinases have indistinguishable C subunits, but different R subunits. The small ciliary enzyme, like the cell-body enzyme, contains R₄₄, whereas R₄₈ is the R subunit of the large enzyme.     

Purification and properties of NADP-dependent glutamate dehydrogenase from Sphaerostilbe repens

NADP-dependent glutamate dehydrogenase (EC 1.4.1.4) extracted from Sphaerostilbe repens was purified to homogeneity by using ammonium sullate fractionation hydroxyapatite and DEAE-cellulose column chromatography and, finally, preparative polyacrylamide gel electrophoresis. The turnover number of the enzyme for the amination reaction was about 66000 mol substrate transformed min^-1 (molecule of GDH)^-1. Molecular weight of the native enzyme was estimated to be 280000 dalton by polyacrylamide gradient gel electrophoresis. The same technique in the presence of sodium dodecyl sulfatc gave a single protein band that corresponded to the subunit molecular weight of 48000 dalton. Thus, it is concluded that NADP-GDH is composed of six identical polypeptidic chains.
The pH optimums were 6.9 and 8.4 for the forward and reverse reactions respectively. The NADP-GDH lost practically none of its activity for ten days at 4°C and for 15 h at room temperature, but was inactivated by higher temperatures. Thiol compounds such as 2-mercaptoethanol and dithiolhrcitol protected the enzyme from rapid inactivation. The Michaelis constants for GDH were 0.64, 0.049. 0.043 and 5.5 m M for α-ketoglutaratc. NADPH, NADP and glutamate, respectively. The enzyme had a negative cooperativity for ammonium (Hill number of 0.66), and its K_m value increased from 2.6 to 21.2 m M when the ammonium concentration exceeded 16 m M . The deamination reaction was highly sensitive to inhibition by ammonium, while the amination reaction was only slightly inhibited by glutamate. These results, considered together with the K_m values, indicate that the NADP-GDH in Sphaerostilbe repens is primarily concerned with glutamate biosynthesis.     

Molecular genetics of avian proteins. XL Egg proteins of Gallus gallus, G. sonnerati and hybrids

By a variety of electrophoretic procedures it has been found that Gallus gallus , whether as jungle fowl or as chickens, differs consistently from Sonnerat's jungle fowl, G. sonnerati , in three egg white proteins: G₃ ovoglobulin, G₂ ovoglobulin and glutamyl peptidase. The electrophoretic patterns of egg white hybrids between G. gallus and G. sonnerati are identical to those obtained after simpiy mixing the egg whites; there is no evidence for hybrid protein zones. Although Japanese data on serum amylase can be interpreted as indicating introgressive hybridization in the origin of the domestic fowl, so far the egg protein data are negative in this respect.     

NADP+-dependent glutamate dehydrogenase from the obligate methylotroph methylobacillus flagellatum

Abstract NADP-dependent glutamate dehydrogenase (GDH; E.C.1.4.1.4) was purified from an obligate methylotroph Methylobacillus flagellatum using ammonium sulphate precipitation, DEAE-Sepharose and dye-ligand Procion red HE3B column chromatography and Sephacryl S-200 gel-filtration. The M_r of the native enzyme was estimated to be 300 000 (±5000). The enzyme consists of six identical subunits with an M_{r of} 47 000 (±3000) (SDS-PAGE). The enzyme has a pH optimum of 8.0 when participating in amination and 9.5 in deamination. Michaelis-Menten kinetics were observed for both reactions. The apparent K_m values were 1.33 mM, 0.032 mM, 11.5 mM, 7.0 mM and 0.014 mM for α-ketoglutarate, NADPH, NH₄⁺, glutamate and NADP⁺, respectively. The enzyme was highly specific for all the substrates and was insensitive to inhibitors. It plays an exclusively anabolic role in the cells.     

Evidence for independent origin of two spring‐spawning ciscoes (Salmoniformes: Coregonidae) in Germany

Combined analyses of mitochondrial DNA (mtDNA) and microsatellite loci were performed to assess the genetic differentiation of two spring‐spawning ciscoes from each other and from sympatric Coregonus albula in two German lakes. Polymorphism was screened at six microsatellite loci and mtDNA for a total of 247 and 94 ciscoes, respectively. Microsatellite data showed a weak differentiation between spring‐spawning Coregonus fontanae and sympatric C. albula in Lake Stechlin ( F _ST = 0–0·008), whereas a significant differentiation was observed between spring‐spawning Coregonus lucinensis and sympatric C. albula in Lake Breiter Luzin ( F _ST = 0·013–0·039). A more pronounced genetic difference was observed between both spring‐spawning species ( F _ST = 0·05–0·128). Shared mtDNA haplotypes among sympatric species within both Lake Stechlin and Lake Breiter Luzin were observed, whereas no haplotype was shared between C. fontanae and C. lucinensis . These results suggest an independent origin for spring‐spawning ciscoes in each lake. Evidence is also provided for mtDNA introgression of Coregonus sardinella into C. lucinensis and C. albula in Lake Breiter Luzin. Postglacially, this species or at least a population which showed mtDNA introgression has colonized the Baltic Sea basin up to the glacial margin that was located between Lakes Stechlin and Breiter Luzin.     

Purification and characterization of xylanase from alkali-tolerant Aspergillus fischeri Fxn1

Abstract Alkali-tolerant Aspergillus fischeri Fxn1 produced two extracellular xylanases. The major xylanase ( M _r 31000) was purified to electrophoretic homogeneity by ammonium sulfate precipitation, anion exchange chromatography and preparatory PAGE. Xylose was the major hydrolysis product from oat spelt and birch wood xylans. It was completely free of cellulolytic activities. The optimum pH and temperature were 6.0 and 60 °C, respectively. pH stability ranged from 5 to 9.5 and the t_{1 / 2} at 50 °C was 490 min. It had a K _m of 4.88 mg ml⁻¹and a V _max of 588 μmol min⁻¹ mg⁻¹. The activity was inhibited (95%) by AlCl₃ (10 mM). This enzyme appears to be novel and will be useful for studies on the mechanism of hydrolysis of xylan by xylanolytic enzymes.     

Effects of Phospholipases on the Kinetic Properties of Rat Striatal Membrane-Bound Tyrosine Hydroxylase

Abstract: Rat striatal tyrosine hydroxylase can be isolated in both a soluble and a synaptic membrane-bound form. The membrane-bound enzyme, which exhibits lower K _ms for both tyrosine (7 μ M ) and reduced pterin cofactor (110 μ M ) relative to the soluble enzyme (47 μ M and 940 μ M , respectively), can be released from the membrane fraction with mild detergent, and concomitantly its kinetic properties revert to those of the soluble enzyme. Treatment of membrane-bound tyrosine hydroxylase with C. perfringens phospholipase C increased the K _m of the enzyme for tyrosine to 27 μ M and the V _max by 60% without changing the K _m for cofactor. In contrast, treatment of membrane-bound tyrosine hydroxylase with V. russelli phospholipase A₂ increased the K _m for tyrosine to 48 μ M increased the V _max and increased the K _m for cofactor to 560 μ M . The enzyme remained bound to the membrane fraction following both phospholipase treatments. Addition of phospholipids to treated enzyme could partially reverse the effects of phospholipase A₂ treatment, but not the effects of phospholipase C treatment. The kinetic properties of phospholipase-treated, detergent-solubilized tyrosine hydroxylase were identical to those of the control solubilized enzyme. Tyrosine hydroxylase appears to interact with synaptic membrane components to produce at least two separately determined consequences for the kinetic properties of the enzyme.     

Seasonal changes in the chemical composition of fish body and nutritional value of the muscle of the pollan (Coregonus pollan Thompson) from Lough Neagh,Northern Ireland

Studies on the chemical composition of adult pollan were carried out monthly from January to December 1977. Sex, weight of scaled fillet, and gonads were examined in 184 fish. Chemical composition which includes water, fat and ash content was analysed in the whole fish, muscle and gonads. This paper attempts to account for the fat and protein flow within fish of both sexes during gonad maturation. Extreme differences between males and females have been recorded in the fat deposition process during summer and spawning period. In spite of our fragmentary knowledge of spawning behaviour in pollan, an explanation is offered for these phenomena. The changes in fat content of female gonads were followed closely throughout the year and the cost of egg production was estimated as a percentage of the amount of fat deposited in the body. Since a similar growth pattern was found for both sexes of pollan, differences in feeding intensity might account for the difference in energy expenditure. Amino acid content was analysed in muscle and gonads and an Essential Amino Acid Index (EAAI) was calculated. There were some changes in EAAI which depended on sex and season. Finally, a new method for evaluation of muscle production expressed as fat and protein is used to determine the most suitable time for fish harvesting.     

Immunological, Physical, and Chemical Evidence for the Identity of Brain and Kidney Post-Proline Cleaving Enzyme

Abstract: Recent studies from this laboratory have suggested a similarity, if not identity, of thyrotropin releasing factor (TRF) deamidase and post-proline cleaving enzyme. Bovine brain TRF deamidase was purified to homogeneity and used to elicit antibodies to the enzyme. These antibodies were used to demonstrate identical immunological reactivity between rat brain TRF deamidase and rat kidney post-proline cleaving enzyme. In addition, both proteins exhibit a molecular weight of 75,000, and have identical K_m values for the synthetic substrate pGlu-( N -benzyl- l -His)-Pro-β-naphthylamide and identical K ₁ values for TRF and luteinizing hormone releasing factor as inhibitors. Finally, the enzymes exhibit the same sensitivities to inhibition by mercury, iodoacetamide, N -ethylmaleimide, and 5, 5'-dithiobis-(2-nitrobenzoic acid). These results strongly suggest that brain TRF deamidase and kidney postproline cleaving enzyme are identical.     

The incidence, numbers and types of Listeria monocytogenes isolated from farm bulk tank milks

Bulk tank milk from 160 producers was tested for Listeria monocytogenes at three monthly intervals over 1 year. Twenty-five producers were positive, most on a single occasion, only seven were positive on three or more of the four samplings. Listeria monocytogenes numbers were low, usually <1 ml^-1, the highest was 35 ml^-1. All isolates were serotype 1, the use of multilocus enzyme electrophoresis on representative isolates gave nine different electrophoretic types, two have been associated with listeriosis in humans or animals, a further two had only been isolated from one other source (silage or faeces), while the majority (5) were unique to milk.     

Human glutathione S-transferases. Characterization of the anionic forms from lung and placenta.

Anionic glutathione S-transferases were purified from human lung and placenta. Chemical and immunochemical characterization, including polyacrylamide-gel electrophoresis, gave strong evidence that the anionic lung and placental enzymes are chemically similar, if not identical, proteins. The electrophoretic mobilities of both proteins were identical in conventional alkaline gels as well as in gels containing sodium dodecyl sulphate. Gel filtration of the intact active enzyme established an Mr value of 45000; however, with sodium dodecyl sulphate/polyacrylamide-gel electrophoresis under dissociating conditions a subunit Mr of 22500 was obtained. Amino acid sequence analysis of the N-terminal region of the placental enzyme revealed a single polypeptide sequence identical with that of lung. Results obtained from immunoelectrophoresis, immunotitration, double immunodiffusion and rocket immunoelectrophoresis also indicated the anionic lung and placental enzymes to be closely similar. The chemical similarity of these two proteins was further supported by protein compositional analysis and fragment analysis after chemical hydrolysis. Immunochemical comparison of the anionic lung and placental enzymes with human liver glutathione S-transferases revealed cross-reactivity with the anionic omega enzyme, but no cross-reactivity was detectable with the cationic enzymes. Comparison of the N-terminal region of the human anionic enzyme with reported sequences of rat liver glutathione S-transferases gave strong evidence of chemical similarity, indicating that these enzymes are evolutionarily related. However, computer analysis of the 30-residue N-terminal sequence did not show any significant chemical similarity to any other reported protein sequence, pointing to the fact that the glutathione S-transferases represent a unique class of proteins.     

Purification and Characterization of Bovine Brain 5'-Nucleotidase

Abstract: The 5'-nucleotidase located in the cytoplasmic fraction of bovine brain cortex was purified to electrophoretic homogeneity. The molecular weight was 134,000 daltons in the presence of sodium deoxycholate, whereas the enzyme formed high molecular weight aggregates in the absence of detergent. The purified enzyme showed the same kinetic and electrophoretic behaviour as the enzyme present in the original cytoplasmic fraction, and the presence of surfactants did not change the K_m and V_m, values. The nucleotidase from this source was a phosphohydrolase of 5'-mononucleotides acting on the deoxyribonucleotides and ribonucleotides of purines and pyrimidines. 5'-IMP was the preferred substrate; the optimum pH was 7.5. The study of the influence of the temperature on the initial reaction rates allowed calculation of the δE_a, and δH^o values. The variation of V_m and K_m with a change in pH suggests the existence of a sulfhydryl group and an imidazole group in the enzymesubstrate complex.