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.     

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.     

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 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.     

Systematics of the Irish pollan (Coregonus pollan Thompson): an electrophoretic comparison with other Holarctic Coregoninae

Evidence is presented on the genetic relationships of 35 coregonine populations from Alaska, Britain, Ireland, Finland and Sweden. This evidence is derived from an electrophoretic analysis of 27 enzyme loci and additional 'general protein loci'. The Irish pollan C. pollan and the Alaskan C. autumnalis gave identical electrophoretic patterns for all proteins suggesting that they are conspecific and separated only since the last glaciation. C. peled, C. albula and the ' C. lavaretus' complex gave unique patterns for a number of proteins. The F_n C. oxyrhynchus X C albula hybrids, from a lake where no other coregonines occur gave a unique pattern for the enzyme phosphoglucose isomerase but all other enzymes were electrophoretically identical to the C. oxyrhynchus parent and the mean gill raker number was closer to this species than in the F₁ hybrid.     

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.     

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 seasonal cycle of condition in the pollan, Coregonus autumnalis pollan Thompson, of Lough Neagh, Northern Ireland

The length–weight relationship for Lough Neagh pollan was log W= 3·2 log L –2·24. Covariance analysis indicated that there were no differences between the sexes, with maturity, or between years. While a seasonal cycle in relative condition was in phase with gonad development during late summer and autumn, changes in somatic condition presented a more complex pattern. Somatic condition increased in spring, as did the quantity and diversity of food consumed. Despite good conditions for feeding and growth, there was an autumn fall in somatic condition, caused by the diversion of energy to gonad growth.     

The influence of light environment on depth of visual feeding by larvae and fry of Coregonus pollan (Thompson) in Lough Neagh

The depth limits for visual feeding by pollan larvae and fry, Coregonus pollan , were determined in Lough Neagh, Northern Ireland, by combining laboratory estimates of the minimum light threshold for feeding activity with field measurements of spectral, diurnal and seasonal changes in light penetration. Although feeding thresholds were lowest in the blue light (400–490 nm), the rapid attenuation of this region in the lake meant that the depth limits of feeding in situ were determined by response to the green region (490–595 nm). Effects of changes in irradiance and light penetration on the depth of feeding are considered during a seasonal study. Increased sensitivity, as the juvenile stages develop, may be offset by reduced light penetration due to algal growth. Over an annual period the maximum feeding depth for pollan varied between 2.6 and 4.1 m. In the juvenile stages of two other predatory species from the lake, perch, Perca fluviatilis , and pike, Esox lucius , the corresponding ranges were 1.1–1.9 m and 2.7–4.6 m respectively.     

The Spawning and Early Life History of the Pollan (Coregonus pollan THOMPSON) in Lough Neagh,Northern Ireland

Studies had been carried out on the local non-migratory whitefish. Spawning behaviour and light conditions on the spawning ground are recorded. After artificial spawning, embryonal development took place under controlled conditions and the larvae were reared. Detailed characteristics of swim bladder creation and differentiation of the digestive tract are given. Distribution and number of pollan larvae near the spawning area and in the open lake were examined. Data are presented concerning the growth rates of larvae and fry in captivity and under lake conditions. Ecological data related to other coregonids are discussed and compared with the present study.     

Studies on the Feeding of Coregonus pollan (Thompson) Alevins and Fry in Lough Neagh

Pollan alevins and fry were collected in the open lake between March and July. Fish were measured in total length, upper (U_j) and lower (L_j) jaws and weighed. The gape-height was calculated according to two different formulae. For the examined fish the relationship between total length (L_t) and gape-height (D) was found to be D=0.092 L_t—0.306. The size of food in the gut content was measured, and this increased during fish growth, but amounted to 13.2–26.0 % of D. In the first food of pollan alevins, nauplii and copepodites dominated, but after the alevins had reached 20 mg, copepods appeared to be more frequent food items. In the middle of May, Daphnia longispina was found in the food of pollan fry with an individual weight over 45 mg. Benthic invertebrate fauna were taken after the fish weighed more than 1.4 g. Chironomus anthracinus and Chironomus sp. larvae were among the food item dominants.     

A multidisciplinary approach to the systematics of Proteocephalus macrocephalus (Creplin, 1825) (Cestoda: Proteocephalidae)

The tapeworm Proteocephalus macrocephalus (Creplin, 1825), a parasite of the eel Anguilla anguilla, was characterised using morphological and genetic characters. The species is morphologically typified mainly by features of the scolex (i.e. shape and size of an apical organ which is formed early during the development in an intermediate host) and strobila (i.e. regularly rectangular proglottides, morphology of the vagina and anterior position of the seminal receptacle). Genetically, P. macrocephalus was compared with two congeners, P. percae and P. exiguus. Characters enabling differentiation of P. macrocephalus were as follows: fixed allelic differences at Got, Pgm and Gapdh loci, metrical features of chromosomes Nos 1, 2 and 7, and species-specific fragments obtained by RAPD method using 13 random primers.     

Species of Proteocephalus Weinland, 1858 (Cestoda: Proteocephalidae), parasites of coregonid and salmonid fishes from North America: taxonomic reappraisal

A taxonomic study of species of Proteocephalus Weinland, 1858 (Cestoda: Proteocephalidae), from coregonid and salmonid fishes in North America, based largely on their type specimens, was carried out. None of the taxa studied possesses obvious autapomorphies that would justify its validity. On the contrary, all species share the following diagnostic features typical of Proteocephalus longicollis (Zeder, 1800) (syn. Proteocephalus exiguus La Rue, 1911), a polymorphic and widely distributed parasite in the Holarctic: (1) a spherical or club-shaped scolex, with sublaterally situated suckers and a vestigial but distinct and relatively large apical sucker; (2) the vagina possessing a well-developed vaginal sphincter and crossing mostly ventrally the proximal part of the cirrus sac; and (3) a long, thick-walled cirrus sac, overlapping vitelline follicles medially by more than its proximal half. Accordingly, Proteocephalus pusillus Ward, 1910; P. laruei Faust, 1920; "P. obtundus" La Rue, 1920 (nomen nudum); P. arcticus Cooper, 1921; P. wickliffi Hunter and Bangham, 1933; P. parallacticus MacLulich, 1943; P. californicus Haderlie, 1950; P. salmonidicola Alexander, 1951; and P. primaverus Neiland, 1952 are considered junior synonyms of P. longicollis.     

内蒙古始新世梳趾鼠类化石

描述了４属１０种梳趾鼠类化石（Ｇｏｂｉｏｍｙｓ ｎｅｉｍｏｎｇｏｌｅｎｓｉｓ, Ｇ． ｅｘｉｇｕｕｓ（新种）, Ｇ． ｃｆ．Ｇ．ｅｘｉｇｕｕｓ,Ｇ．ａｓｉａｔｉｃｕｓ（新种）,Ｇｏｂｉｏｍｙｓ？ｓｐｐ．,Ａｄｖｅｎｉｍｕｓ　ｃｆ．Ａ．ｂｏｈｌｉｎｉ,Ａ．ｃｆ．Ａ．ｂｕｒｋｅｉ, Ｙｕｏｍｙｓ ｓｐ．和Ｐｒｏｔａｔａｒｏｍｙｓ　ｓｐ．）．以Ｍｅｒｇｅｎｏｍｙｓ　ｎｅｉｍｏｎｇｏｌｅｎｓｉｓ作属型种建了一新属,Ｇｏｂｉｏｍｙｓ。其特征是：门齿孔大;具Ｐ３;颊齿齿冠低,主尖明显,但不膨大,齿凹开阔;Ｐ４／ｐ４非臼齿化;上臼齿宽大于长,后脊较发育;Ｍ１和Ｍ２具内脊;下外脊和下次小尖位置偏外。Ｇ．ｅｘｉｇｕｕｓ的特点是：个体较小,上颌骨颧突根在Ｐ３之前,下臼齿缺下原失后臂舌部、下内尖臂和下前齿带．Ｇ．ａｓｉａｔｉｃｕｓ的上颌骨颧突后缘在Ｐ３的外方;臼齿具较发达的齿脊;上臼齿较宽短,后小尖较弱;下臼齿具较发达的内尖臂和前齿带。 Ｇｏｂｉｏｍｙｉｄａｅ新科包括Ｇｏｂｉｏｍｙｓ, Ｍｅｒｇｅｎｏｍｙｓ,Ｙｏｕｎｇｏｍｙｓ和哈萨克斯坦的未命名的新属等４属,组成与梳趾鼠科相对的姐妹群。其主要特征是,下颌骨缺咬肌窝上嵴。颊齿低冠,近于丘形     

Construction of an effective host-vector system for the yeast Saccharomyces exiguus Yp74L-3.

An effective host-vector system specific to the yeast Saccharomyces exiguus Yp74L-3 was constructed to promote the molecular genetic analyses for the yeast. To obtain a stable reversionless host strain, we constructed an S. exiguus strain carrying leu2::ScURA3 by disrupting the S. exiguus LEU2 gene with the S. cerevisiae URA3 gene. A vector plasmid unique to S. exiguus was subsequently developed by inserting both the LEU2 gene and an ARS cloned from S. exiguus into an Escherichia coli phagemid, pUC119. The vector constructed, pTH119 was able to transform the S. exiguus leu2::ScURA3 strain to Leu+ efficiently. The stability of the vector in the S. exiguus host cells resembled that of a YRp-type vector in S. cerevisiae.     

Location-dependent infection of fish parasites in Lake Constance

Perch Perca fluviatilis and roach Rutilus rutilus were caught at various locations around Lake Constance (Bodensee). Infection of perch and roach with the eyeflukes Diplostomum spathaceum and Tylodelphis clavata was greatest in the western location (Bottighofen). The varied occurrence of parasite species at different locations indicated that maximum interchange between fish populations was slight. Whitefish Coregonus lavaretus migrating up the River Rhine were less infected with both the tapeworm Proteocephalus exiguus and the copepod Ergasilus sieboldi than whitefish from the middle of the lake. Some of the parasites had already left their hosts. Newly established infections were not found in migrating whitefish.     

The genetic relationships of the coregonid fishes of Britain and Ireland indicated by electrophoretic analysis of tissue proteins

The electrophoretic patterns of the general proteins, esterases, creatine kinase and phosphoglucomutase of white muscle from Lough Neagh pollan, Lough Erne pollan, Lake Bala gwyniad, Loch Lomond powan, Haweswater schelly and Bassenthwaite vendace are consistently of three types. It is therefore suggested that the coregonids examined are three distinct species: the pollans; gwyniad, powan and schelly; vendace. Vendace is genetically closer to the gwyniad group than to the pollans.     

Production protocol for and storage efficacy of an anthocorid predator Cardiastethus exiguus Poppius

Cardiastethus exiguus Poppius is an indigenous anthocorid predator of eggs and neonates of the notorious pest,coconut black-headed caterpillar Opisina arenosella Walker in India.At the National Bureau of Agriculturally Important Insects(Indian Council of Agricultural Research),Bangalore,India,a simple mass production protocol was developed for multiplying C.exiguus using UV-irradiated eggs of alternate laboratory host Corcyra cephalonica Stainton.Field evaluation of the predator in the states of Kerala and Karnataka indicated that this predator could bring about a significant reduction in the pest population.Subsequently,the need was felt to investigate the storage efficacy of the eggs and adults of C.exiguus so that sufficient numbers could be accumulated and transportation of the predator could be planned for field releases.Low temperature storage studies indicated that C.exiguus eggs can be safely stored for up to 5 days at 10℃ and 10 days at 15℃ and incubation period could be staggered for up to 10 and 13 days,respectively.The longevity of the C.exiguus adults was significantly reduced due to low temperature storage.However,for adult females,a storage temperature of 15℃ for 15 days could be recommended as they could live for a more than a month after removal from storage and their progeny production was comparable to that of the control adults.     

A taxonomic revision of the pipunculid fly genus Chalarus Walker, with particular reference to the European fauna

Twenty-one species of Chalarus Walker are described from Europe, 11 of them new. The puparial remains of 15 species are described. Type material of all previously described Chalarus species except C. velutinus (Macquart, 1835) was examined. The status of C. holosericeus (Meigen, 1824) is revised, and exiguus (Haliday, 1833) is confirmed as a valid species. Lectotypes are designated for C. holosericeus and C. spurius (Fallén, 1816). Five species-groups are tentatively proposed. Separate keys to females and males are given. The status of Chalarus species described from outside Europe is discussed, and two of these, C. kamijoi Morakote, in Morakote & Hirashima (1990) and C. konishii Morakote, in Morakote & Hirashima (1990), are synonymized with fimbriatus Coe and exiguus (Haliday) respectively. The functional significance of some taxonomic characters, particularly of the eyes and ovipositor, is discussed.     

Growth requirements of san francisco sour dough yeasts and bakers' yeast

The growth requirements of several yeasts isolated from San Francisco sour dough mother sponges were compared with those of bakers' yeast. The sour dough yeasts studied were one strain of Saccharomyces uvarum, one strain of S. inusitatus, and four strains of S. exiguus. S. inusitatus was the only yeast found to have an amino acid requirement, namely, methionine. All of the yeasts had an absolute requirement for pantothenic acid and a partial requirement for biotin. Inositol was stimulatory to all except bakers' yeast. All strains of S. exiguus required niacin and thiamine. Interestingly, S. inusitatus, the only yeast that required methionine, also needed folic acid. For optimal growth of S. exiguus in a molasses medium, supplementation with thiamine was required.