Electrophoretic identity between allis shad, Alosa alosa (L.), and twaite shad, A.fallax (Lacépède)

Morphological characteristics as well as electrophoretic polymorphism have been analysed in eight samples of allis shad, Alosa alosa (L.) and twaite shad, Alosa fallax (Lacepede), collected in the Loire basin and the Gironde-Dordogne system. The morphological characteristics showed that allis and twaite shad were present in these samples. Moreover, specimens with intermediate characteristics were found in the Loire and assumed to be hybrids between the two forms. By contrast, the two species were monomorphic and electrophoretically indistingishable at the 22 loci analysed. Therefore, it cannot be excluded that these two forms correspond to a single species.     

Genetic monitoring of two decades of hybridization between allis shad (Alosa alosa) and twaite shad (Alosa fallax)

Habitat alteration has been implicated in driving hybridization between the sympatric migratory shads Alosa alosa and Alosa fallax. Morphological and molecular evidence is consistent with hybridization across the overlapping range of these species, but the temporal extent of hybrid occurrence and genetic consequences for populations have not been explored. Using eight nuclear microsatellite loci and samples collected between 1989 and 2008 in the Solway Firth (UK), we genetically identified hybrids, studied temporal changes in their frequency, and explored changes in allele frequencies of parental populations. These molecular data confirmed the hybrid status of individuals identified using morphology (number of rakers on the outer gill arch), and enabled separation of hybrids from purebred individuals. Mitochondrial cytochrome-b sequencing revealed the presence of two haplogroups, each predominantly occurring in one species. Heterospecific haplotypes were found in 22.3 and 12.8% of A. alosa and A. fallax individuals, respectively, consistent with backcrossing and suggesting that hybrids are fertile. On average, microsatellite-identified hybrids comprised 12.7% of all samples, but when individuals with cytonuclear discordance were also considered introgressed on average 25.4% of individuals were of hybrid ancestry. Overall, allelic richness remained largely unchanged within species, but there were declines in the inbreeding coefficient (F _IS) of both species and episodes of significant temporal allelic frequency change. Hybrids sampled between 2004 and 2008 showed no evidence of lower fecundity relative to purebred individuals. Together, results suggest that hybridization between shad species in northern Europe is prevalent, and has been ongoing over at least two decades. The challenge is now to understand the extent to which observed patterns are linked to immigration from other populations, and the mechanisms that have prevented species collapse despite apparent hybrid fertility and longstanding introgression of neutral markers.     

Diet of the twaite shad Alosa fallax (Lacépède) (Clupeidae) in the River Tagus Estuary, Portugal

The diet of Alosafallax was studied by means of the frequency of occurrence of prey items. In the Tagus Estuary, shads feed preferentially on fish, with mysids, shrimp, isopods and insects occurring as secondary prey.     

Genetic polymorphism of a haemoglobin chain and adenosine deaminase in European shads: evidence for the existence of two distinct genetic entities with natural hybridization

The degree of genetic differentiation between European shads, Alosa alosa and A. fallax , was studied in populations from different Portuguese hydrographic basins. Using isoelectric focusing, polymorphic variation was detected in a haemoglobin (HB) chain and in adenosine deaminase (ADA). These polymorphisms are shared by the two species but show significant differences in their gene frequency distributions. Individuals with intermediate morphological characteristics were found to exhibit intermediate allele frequencies. While not completely excluding introgression, our results strongly support the existence of two distinct species that can hybridize.     

The biology of the twaite shad, Alosa fallax fallax (Lacépède), in the Severn Estuary

The estuarine biology of the twaite shad was studied in the Severn Estuary. Adults enter the estuary at the start of the freshwater phase of their spawning migration between April and June. Peak immigration generally occurs in May and is associated with temperatures in the range 10.6–12.3°C. The mean (± s.d. ) instantaneous mortality rate for the mature population was 0.53±0.18. The effect of additional mortality on the spawning population was modelled assuming constant recruitment and no density-dependent effects.
Juvenile twaite shad are present in the estuary from July until they emigrate seaward during the autumn. A portion of these fish re-enter the estuary the following April–May and remain until late summer/early autumn before once more migrating seaward.
The 0 + age group feed mainly on harpacticoid and calanoid copepods and mysids, the relative preponderance of these in the diet being apparently related to tidal conditions. The possible implications of the proposed tidal power barrage in the Severn Estuary on the twaite shad population are discussed in relation to movement, diet and additional mortality of the mature population.     

Growth and movements of the twaite shad, Alosa fallax (Lacépède), in the Severn Estuary

Between July 1974 and April 1977, appreciable numbers of 0 group twaite shad, Alosa fallax , have been collected from the cooling water intake screens of the Nuclear Power Stations at Oldbury-upon-Severn and Berkeley on the Severn Estuary and at Hinkley Point on the Bristol Channel, England. Young of the year first appeared at Oldbury in July at a size of approximately 32 mm standard length, and grew to approximately 61 mm by October. The downstream migration in the late summer and autumn appeared to be closely correlated with water temperature since movement reached a peak soon after the temperature in the Estuary had declined below 19° C, and ceased altogether below 9° C. Thereafter, there was virtually no movement of shad until temperatures rose sharply above 7° C in the spring. Maturing adult twaite shad were captured in late April and May as they moved into freshwater to spawn, probably in mid-June. Males were recorded slightly earlier during the migration and were generally younger than females. Furthermore, mean lengths and weights for individuals belonging to the different age classes indicated that males were also smaller. Logarithmic relationships between length and weight of young and adult A. fallax and for the variation with size in the number of rakers on the first gill arch are presented.     

Morphometric, meristic character and electrophoretic analyses of two Irish populations of twaite shad, Alosa fallax (Lacépède)

Since 1911 a rare lacustrine form of twaite shad, Alosa fallax killarnensis Regan (1916), has been known to occur in the Killarney Lakes. During the summers of 1985 and 1986 a gill netting programme in Lough Leane for brown trout, Salmo trutta L., yielded 32 shad (1985) and 64 shad (1986) as a by-catch. These fish were deep frozen and compared with a sample of 59 marine twaite shad, taken on rod and line from St Mullin's, Co. Carlow, which had entered the River Barrow to spawn.
Morphometric, meristic and electrophoretic character analyses were carried out on the two populations. The three analyses, particularly the isoelectric focusing, confirmed a high degree of genetic similarity. The two major differences found were the dwarfed size of the Killarney shad and the increased numbers of gill rakers carried on the first branchial arch. The merits and demerits of assigning the term subspecies to the Killarney shad are discussed in the light of the available evidence produced.     

Extensive polymorphism at adenosine deaminase in the marine fish Sciaenops ocellatus (L.)

Summary Eleven different allelic variants at the adenosine deaminase (ADA) locus have been detected using vertical starch-gel electrophoresis among 474 individuals of the marine fish Sciaenops ocellatus (L.). Thirty-five of the 66 possible genotypes were observed, and the heterozygosity level at ADA was estimated to be 70·3%. The extensive polymorphism at ADA may prove useful in terms of providing genetic markers for stocking programs using hatchery-raised fish.     

Two new common alleles of erythrocyte adenosine deaminase (ADA) in pigs

New adenosine deaminase variants ADA C and ADA D were found by means of agarose gel electrophoresis in pig erythrocytes. Family data supported the hypothesis that these are controlled by codominant alleles ADAC and ADAD. The ADAC allele was present in Large White (q = 0.076), Landrace (q = 0.037) and their crosses with other breeds. The ADAD allele was present in Duroc (q = 0.067) and its crosses. Allele frequencies for six pig breeds are given.     

Genetic polymorphism of adenosine deaminase and mannose phosphate isomerase in blood of arctic foxes, Alopex lagopus

Blood samples of 70 foxes, including 10 families, have been investigated by horizontal starch gel electrophoresis for the enzymes adenosine deaminase (ADA) and mannose phosphate isomerase (MPI). The observed variation of the enzymes could be explained as a result of one locus with two codominant alleles and one with three respectively. The segregation in the families of the alleles assumed for the two loci is in accordance with this genetic model. The frequency of the two alleles at the Ada locus is about the same and the slowest anodic migrating allele at the Mpi locus is the most frequent.     

Genetic polymorphism of delta-aminolaevulinic acid dehydratase (E.C. 4.2.1.24, ALAD) in the domestic rabbit

A genetic polymorphism of delta-aminolaevulinic acid dehydratase (ALAD) in the domestic rabbit, Oryctolagus cuniculus, was detected by starch gel electrophoresis. Family data (15 matings with 49 offspring) support the genetic model of two common codominant alleles at an autosomal locus. Gene frequencies were calculated in a random sample of 55 mixed breed, unrelated domestic rabbits: ALAD1 = 0.31 and ALAD2 = 0.69.     

Genetic polymorphism of esterase in plasma of American mink (Mustela vison L.)

Plasma samples of 412 minks, including 20 families and representing 15 lines, have been investigated by isoelectric focusing for the enzyme esterase (ES). The observed variation of the enzyme may be explained as a result of one locus with at least seven codominant alleles. The segregation of six alleles assumed for the locus in 20 families supports this genetic model. Genetic divergence among the lines is observed and may be due to founder effect and/or selection.     

Influence of treatment with 3′-deoxyadenosine associated deoxycoformycin on hematological parameters and activity of adenosine deaminase in infected mice with Trypanosoma evansi

This study aimed to verify the effect of 3′-deoxyadenosine and deoxycoformycin on hematologic parameters and adenosine deaminase (ADA) activity in plasma and brain of mice infected with Trypanosoma evansi. Seventy animals were divided into seven groups, which were divided into two subgroups each for sampling on days 4 and 8 post-infection (PI). The groups were composed of three uninfected groups (A–C), namely, not-treated (A), treated with 3′-deoxyadenosine (B), and treated with deoxycoformycin (C) and four infected groups, mice with T. evansi (D–G), namely, not-treated (D), treated with 3′-deoxyadenosine (E), treated with deoxycoformycin (F), and treated with a combination 3′-deoxyadenosine and deoxycoformycin (G). Hematological parameters and ADA activity were evaluated in plasma and brain. Animals in groups B and C exhibited a reduction in the levels of plasma total protein compared group A. Animals in groups D and F showed changes in the hematological parameters. The ADA activity significantly reduced in the animals of groups C, D, F and G. Mice in the group E presented increased ADA activity in plasma. Therefore, we conclude that the treatment interferes significantly in the hematologic parameters in mice infected with T. evansi. On the other hand, when the ADA inhibitor was used we observed a significant decrease in the values of hematocrit, total erythrocytes, and hemoglobin concentration. The deoxycoformycin was able to inhibit the ADA activity of parasite thus it may be one of the mechanisms of efficacy of this treatment.     

Genetic polymorphism of the sixth component of complement (C6) in dogs

Using agarose gel isoelectric focusing and immunoblotting with rabbit anti-rabbit C6, a genetic polymorphism was found in the sixth component of complement (C6) in 18 Asian native breeds or populations and three European breeds of dog. The C6 locus was highly polymorphic. The phenotype distribution data indicated that dog C6 phenotypes were controlled by seven codominant alleles, C6 ^A, C6 ^B, C6 ^C, C6 ^D, C6 ^E, C6 ^F and C6 ^G, at a single autosomal locus. Breed differences were observed among the gene frequencies, especially between Asian and European breeds. Two gene flows from the adjacent areas into Japanese native dogs were postulated.     

Genetic polymorphism of the sixth component of complement (C6) in the pig

Summary
Using agarose gel isoelectric focusing and immunoblotting with rabbit anti-rabbit C6, a genetic polymorphism has been found in the sixth component of complement (C6) in six breeds of pigs. The C6 locus was highly polymorphic. Family data indicated that pig C6 pheno-types were inherited by means of five codomonant alleles named C6 ^A, C6 ^B, C6 ^C, C6 ^D and C6 ^E at a single autosomal locus. C6 deficiency in two of 241 individuals tested was found, which suggested the presence of a null allele in pig populations. Marked breed differences among the gene frequencies and heterozygosities at C6 locus were observed.     

Genetic polymorphism in Norway spruce,Picea abies (L.) Karst,assessed by two-dimensional gel electrophoresis of needle proteins

Summary A comparative analysis of three Norway spruce genotypes by two-dimensional gel electrophoresis is presented. This study has led to the identification of approximately 970 gene products for each genotype. Significant qualitative and quantitative differences have been identified, and qualitative and quantitative divergence indices between genotypes have been computed. Two-dimensional electrophoresis appears to be an efficient tool for studying modifications of gene expression in Norway spruce in response to climatic and pollution stresses.