Interaction between Gammarinema gammari (Nematoda), Microphallus papillorobustus (Trematoda) and their common host Gammarus insensibilis (Amphipoda).

The influence of the nematode Gammarinema gammari on survival, mating success, and fecundity of its host Gammarus insensibilis (Amphipoda) was investigated. The prevalence and the mean intensity of G. gammari were significantly higher in males than in females. There was a positive and significant relationship between the mean number of G. gammari and male body size, suggesting that accumulation of this parasite had no significant effect on the survival of its host. Males that harbored the metacercariae of the trematode Microphallus papillorobustus had a lower number of nematodes than those that did not harbor the trematode. Fecundity was significantly reduced in infected females, and unpaired females tended to be more frequently infected by G. gammari than paired ones. However, we found no evidence for parasite-mediated reduction in male competitiveness because the mean number of G. gammari was not significantly different between paired and unpaired males.     

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.     

Acanthocephalan infections in Atherina boyeri (Pisces: Atherinidae) from Tirso.

Infections by the acanthocephalan Telosentis exiguus (Von Linstow, 1901) and another unknown acanthocephalan were studied in the sand smelt Atherina boyeri (Risso, 1810) from the Tirso River mouth in Sardinia. Only a few specimens of T. exiguus (1 male and 2 cystacanths) were found in the host digestive tract; some larvae of an unidentified acanthocephalan encysted in the liver of A. boyeri were also found and are described.     

Do distantly related parasites rely on the same proximate factors to alter the behaviour of their hosts?

Phylogenetically unrelated parasites often increase the chances of their transmission by inducing similar phenotypic changes in their hosts. However, it is not known whether these convergent strategies rely on the same biochemical precursors. In this paper, we explored such aspects by studying two gammarid species (Gammarus insensibilis and Gammarus pulex; Crustacea: Amphipoda: Gammaridae) serving as intermediate hosts in the life cycle of two distantly related parasites: the trematode, Microphallus papillorobustus and the acanthocephalan, Polymorphus minutus. Both these parasite species are known to manipulate the behaviour of their amphipod hosts, bringing them towards the water surface, where they are preferentially eaten by aquatic birds (definitive hosts). By studying and comparing the brains of infected G. insensibilis and G. pulex with proteomics tools, we have elucidated some of the proximate causes involved in the parasite-induced alterations of host behaviour for each system. Protein identifications suggest that altered physiological compartments in hosts can be similar (e.g. immunoneural connexions) or different (e.g. vision process), and hence specific to the host-parasite association considered. Moreover, proteins required to alter the same physiological compartment can be specific or conversely common in both systems, illustrating in the latter case a molecular convergence in the proximate mechanisms of manipulation.     

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.     

Egg production by metacercariae of Microphallus papillorobustus: a reproductive insurance?

This study aimed to determine whether metacercariae of Microphallus papillorobustus (Trematoda: Microphallidae) produce eggs by self-fertilization when their intermediate host, the gammarid Gammarus insensibilis, dies before being eaten by predatory definitive hosts. Such a mechanism would allow the parasite to reproduce even if transmission fails. The percentage of metacercariae that produced eggs and the mean number of eggs were significantly higher in metacercariae placed in a Ringer's solution compared with those in salt water or metacercariae remaining inside the dead gammarid. The lack of egg production in metacercariae removed from dead gammarids in the field supported the idea that self-fertilization is not, for this parasite, a mechanism of reproductive insurance when establishment in the definitive hosts fails.     

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.     

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     

Effects of Microphallus papillorobustus (Platyhelminthes: Trematoda) on serotonergic immunoreactivity and neuronal architecture in the brain of Gammarus insensibilis (Crustacea: Amphipoda)

The larval flatworm Microphallus papillorobustus encysts in the protocerebrum of its intermediate host, Gammarus insensibilis, and changes the gammarid's responses to mechanical and photic stimuli. The resulting aberrant escape behaviour renders infected gammarids more susceptible to predation by birds, the definitive hosts of the parasite. We used immunocytochemical methods to explore the mechanisms underlying these subtle behavioural modifications. Whole mounts of gammarid brains were labelled with fluorescent anti-serotonin and anti-synapsin antibodies and viewed using confocal microscopy. Two types of change were observed in infected brains: the intensity of the serotonergic label was altered in specific regions of the brain, and the architecture of some serotonergic tracts and neurons was affected. A morphometric analysis of the distribution of the label showed that serotonergic immunoreactivity was decreased significantly (by 62%) in the optic neuropils, but not in the olfactory lobes, in the presence of the parasite. In addition, the optic tracts and the tritocerebral giant neurons were stunted in parasitized individuals. Published evidence demonstrates changes in serotonin levels in hosts ranging from crustaceans to mammals infected by parasites as diverse as protozoans and helminths. The present study suggests that the degeneration of discrete sets of serotonergic neurons might underlie the serotonergic imbalance and thus contribute to host manipulation.     

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.     

New species of Boletellus from Guyana

Boletellus exiguus sp. nov. and Boletellus dicymbophilus sp. nov. (Boletaceae, Boletales, Basidiomycota) are described as new to science. These boletes were collected from tropical forests dominated by ectomycorrhizal Dicymbe corymbosa (Caesalpiniaceae) in the Pakaraima Mountains of western Guyana.     

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.     

Field evidence for density-dependent effects in the trematode Microphallus papillorobustus in its manipulated host, Gammarus insensibilis

Numerous studies have demonstrated that parasites with complex life cycles frequently manipulate the phenotype of their hosts to increase their transmission rate. Little is known, however, concerning density-dependent processes within infrapopulations of manipulative parasites--whether parasites cooperate to manipulate the host, whether competition counteracts with these potential cooperative benefits, or both. Here we explored these ideas, focusing on the association between the manipulative trematode Microphallus papillorobustus and its second intermediate host, the gammarid Gammarus insensibilis. From the data collected in the field, we found no evidence that co-occurring M. papillorobustus individuals benefit from the presence of conspecifics; instead, individuals in larger infrapopulations suffered reduced size and fecundity. Thus, the net effect of increasing density suggests that competition rather than cooperation is the dominant force in infrapopulations of M. papillorobustus.     

Life cycle of Gnathostoma nipponicum Yamaguti, 1941.

The life cycle of Gnathostoma nipponicum was examined by field survey and by experimental infection of animals with the larvae. Naturally infected larval G. nipponicum were found in loaches, catfish, and snakes. Experimentally, loaches, killifishes, frogs, salamanders, mice, and rats were successfully infected with the early third-stage larvae of G. nipponicum obtained from copepods (the first intermediate host), whereas snakes, quails, and weasels were not. Frogs, snakes, quails, and rats were experimentally infected with the advanced third-stage larvae (AdL3) from loaches. These results reveal that some species of fishes, amphibians and mammals can act as the second intermediate host and that some species of reptiles, birds and mammals can act as a paratenic host. The life cycle was completed in weasels, the definitive host, which were infected with AdL3 from loaches and started to evacuate eggs of G. nipponicun in faeces on days 65-90 postinfection.     

The palearctic oystercatcher Haematopus ostralegus, a natural definitive host for Gymnophalloides seoi

In order to verify the role of migrating birds as natural definitive hosts for Gymnophalloides seoi (Gymnophallidae), Palearctic oystercatchers, Haematopus ostralegus, were caught from several western coastal areas in the Republic of Korea and examined for intestinal flukes. Five (71.4%) of 7 oystercatchers were infected with 302-1,660 (mean 892) adult G. seoi. In intestinal sections of the host, worms were found in the intervillous space of the mucosal layer. We conclude that the oystercatcher is a natural definitive host for G. seoi.     

Microorganisms of the San Francisco Sour Dough Bread Process: I. Yeasts Responsible for the Leavening Action

Two hundred isolates from San Francisco sour dough French bread fermentations (40 from each of five different bakeries) were screened by fermentation tests and for their ability to grow in the presence of cycloheximide (Actidione). All of the isolates from four of the bakeries and 70% of those from the fifth were unable to utilize maltose but grew well on other sugars, even in the presence of cycloheximide. The remaining few isolates from the fifth bakery utilized maltose but not galactose and were inhibited by cycloheximide. No bakers' yeast types were found. Sixteen of the maltose-negative and five of the galactose-negative isolates were subjected to more rigorous taxonomic procedures. All of the maltose-negative isolates were identified as asporogenous strains of Saccharomyces exiguus (Torulopsis holmii) and the galactose-negative ones, as S. inusitatus. The predominance of S. exiguus, its vigor in the particular acidic environment of the sour dough, and the correlation of its numbers with the leavening function constitute strong evidence on the role of this organism in the sour dough system.     

Synonymy of shape Proteocephalus pollanicola Gresson, 1952 (Cestoda: Proteocephalidae), a parasite of pollan,shape Coregonus autumnalis pollan,with shape P. exiguus La Rue, 1911

The systematic status of the tapeworm Proteocephalus pollanicola Gresson, 1952, a parasite of pollan Coregonus autumnalis pollan Thompson, was evaluated on the basis of freshly collected material from the type-locality (Lough Neagh, Northern Ireland). Comparison of morphological, biometrical and DNA data (RAPD method) from P. pollanicola and from P. exiguus La Rue, 1911, a very common parasite of coregonid fish, did not find any substantial differences between them to confirm the validity of P. pollanicola. Accordingly, P. pollanicola is considered to be a synonym of P. exiguus, a widely distributed parasite in the Holarctic.     

Seasonal dynamics of the extent of the infestation of the vendace by the cestode Proteocephalus exiguus (Cestoda, Proteocephalidae) in Karelia

In two lakes of Karelia the infection dynamics of vendace (Coregonus albula L.) with the cestode Proteocephalus exiguus (La Rue) was studied in the summer-autumn period. 2006 specimens of vendace were dissected. Regularities of variations in the infection extensiveness depend on ecological characters of a water body and are modelled by various polynomes.     

Negative influence of Gammarinema gammari (Nematoda) on the fecundity of Microphallus papillorobustus (Trematoda): field and experimental evidence

The gammarid amphipod Gammarus insensibilis frequently harbors adult individuals of the ectoparasitic nematode Gammarinema gammari as well as metacercariae of the trematode Microphallus papillorobostus. After the demonstration in a previous study of a negative relationship between the abundance of these 2 parasites, the nature of the relationship between these 2 parasites was explored in more detail by studying, in the field and in the laboratory, the influence of nematode abundance on trematode fecundity. In gammarids collected in the field, a negative relationship between metacercarial fecundity and the number of co-occurring nematodes was found. By manipulating the nematode abundance in the laboratory, it was confirmed that G. gammari has a negative effect on egg production in M. papillorobustus.