The escape kinetics from the anterior midgut (AM) of Trypanosoma cruzi during the initial steps of infection was assessed in Triatoma infestans, as well as its ability to survive migration in the digestive tract of the vector. All the four strains evaluated survived and reached variable parasite densities. After 49–50 days, YuYu [discrete typing units (DTU) I] strain reached the highest parasite numbers in the rectum followed by Bug (DTU V), CL-Brener (DTU VI) and Dm28c (DTU I). All strains accomplished metacyclogenesis. Bug strain reached the highest numbers of metacyclic trypomastigotes followed by YuYu and CL-Brener/Dm28c. A remarkable parasite reduction in the AM for Bug strain, but not Dm28c was noticed at 72 h of infection. In the posterior midgut + rectum high densities of parasites from both strains were detected at this period indicating the parasites crossed the AM. For Dm28c strain, in infections initiated with trypomastigotes, parasites left AM faster than those starting with epimastigotes. In conclusion, T. cruzi strains from different DTUs were able to infect T. infestans reaching variable parasite densities. The kinetics of migration in the digestive tract may be affected by strain and/or the evolutive form used for infection.

Previous nutritional studies have shown that insulin regulation is different between DT and A strains of gibel carp. As leptin plays a pivotal role in the effects of insulin, we hypothesised that leptin regulation of glucose and lipid metabolism would differ between the two strains. To test our hypothesis, recombinant human leptin was injected into two strains. The results showed that leptin activated the phosphatidylinositol 3-kinase (PI3K)–protein kinase B (AKT), AMP-activated protein kinase–acetyl coenzyme A carboxylase and Janus kinase 2 (JAK2)–signal transducer and activator of transcription (STAT) signalling pathways in both strains. Hypoglycaemia induced by leptin might be due to higher glucose uptake by the liver and muscles together with enhanced glycolytic potential and reduced gluconeogenic potential. Decreased lipogenesis and up-regulated fatty acid oxidation were induced by leptin. In terms of genotype, the PI3K–AKT signalling pathway was more strongly activated by leptin in the muscle tissue of the A strain, as reflected by the heightened phosphorylation of AKT. Furthermore, glycogen content, glycolytic enzyme activity and gluconeogenic capability were higher in the A strain than the DT strain. Strain A had higher levels of fatty acid synthesis and lipolytic capacity in the liver than the DT strain, but the opposite was true in white muscle. Regarding leptin–genotype interactions, the DT strain displayed stronger regulation of glucose metabolism in the liver by leptin as compared with the A strain. Moreover, a more active JAK2–STAT signalling pathway accompanied by enhanced inhibition of fatty acid synthesis by leptin was observed in the DT strain. Overall, the regulation of glucose and lipid metabolism by leptin differed between the two strains, as expected.

An alternative neutron diffractometer performance, which documents the feasibility of using a high-resolution three-axis neutron diffractometer for elastic and plastic deformation studies of bulk metallic polycrystalline samples, is presented. Contrary to the conventional double-axis setting, the suggested alternative consists of an unconventional three-axis set-up employing a bent perfect crystal monochromator and an analyzer with a polycrystalline sample in between. Though the alternative is, for measurements, much more time-consuming, its sensitivity to the change of the diffraction angle of the sample is, however, substantially higher and permits also plastic deformation studies on the basis of analysis of the diffraction line profiles. Moreover, much larger widths (up to 10 mm) of the irradiated gauge volumes can be investigated when just slightly affecting the angular resolution properties of the experimental setting.

A study was conducted of the biological, morphological and molecular characters of 3 strains of Trypanosoma cruzi (SI5, SI8 and SIGR3) isolated from specimens of Triatoma sordida collected in Santo Inácio and a domestic cat. In order to carry out the study, the following parameters were evaluated: pre-patent period, parasitaemia curves, morphology of the parasites, mortality rates, histopathological lesions and molecular typing. The strains presented variable pre-patent periods, low parasitaemia and no animal mortality. The morphological study of trypomastigotes showed a predominance of intermediate-width and short-length forms, as well as low nuclear index. Epimastigotes presented a low nuclear index, intermediate-width forms in strains SI5 and SI8, and large-width forms in SIGR3. A shorter length could be noted in strains SI8 and SIGR3, whereas SI5 displayed an intermediate length. The histopathological study did not detect amastigote nests in tissues. The amplification of the divergent domain of 24Sα rRNA, HSP60 and GPI genes of strains SI5, SI8 and SIGR3 classified the 3 strains into Group II. Biological parameters made it possible to classify the strains isolated in Santo Inácio (BA) into Biodeme III, Zymodeme 1 and Group II of T. cruzi.

We have used a number of molecular genetic approaches to characterize the cervid strain (‘northern form’) of Echinococcus granulosus. PCR–RFLP analysis of the nuclear ITS1 region of the rDNA repeat can readily distinguish the cervid form from other strains of E. granulosus. The complexity of the RFLP patterns obtained suggests that a number of distinct ITS1 types are present in this strain which may represent an inter-strain E. granulosus hybrid. Mitochondrial CO1 sequence of the cervid genotype was ambiguous at 18 positions and closely resembles a cluster of previously characterized E. granulosus genotypes, G1 (common, domestic sheep)/G2 (Tasmanian sheep)/G3 (buffalo). In contrast, mitochondrial ND1 sequence, although unique, suggests that the cervid form is most similar to strains represented by the G6 (camel)/G7 (pig) genotypes. We assume that the CO1 and ND1 sequences obtained for the cervid genotype are linked in a single mitochondrial genome although this is difficult to explain if conventional molecular genetics of mitochondrial DNA are assumed. Based on its unique ND1 sequence and ITS1 PCR–RFLP pattern, the cervid strain appears to represent a distinct genotype (designated G8) of E. granulosus.

Enzyme electrophoresis was used to examine genetic variation within and between populations of Echinococcus granulosus from domestic and sylvatic hosts in western and eastern Australia. Substantial genetic diversity was found within all populations. There was no evidence, however, of genetic differentiation between populations from different hosts or geographic areas. When isolates were grouped into previously described domestic or sylvatic strains on the basis of rostellar hook morphology, most (94%) of the genetic variation occurred within, rather than between strains. These results conflict with the currently accepted theory of separate domestic and sylvatic strains of E. granulosus on the mainland of Australia.

The technique of Random Amplified Polymorphic DNA (RAPD) PCR has been used to detect DNA polymorphisms among Toxoplasma gondii strains. Seven arbitrary oligonucleotides (10-mer) were used as primers to amplify total genomic DNAs and significant genetic heterogeneity was detected among 11 T gondii strains with different virulence for mice. The polymorphisms observed allowed relationship dendrograms of T. gondii strains to be constructed by PHYLIP and PAUP analyses. The genetic relationships of the T. gondii strains generated by 2 analyses using completely different assumptions were similar. Both analyses revealed 2 groups of T. gondii strains, one formed by the 6 virulent strains and the other formed by the 5 avirulent strains. This suggests that the genus Toxoplasma may actually contain 2 groups, correlated with their virulence, which have probably evolved independently following their initial separation. Significant polymorphisms were also detected between 2 different laboratory stocks of the T. gondii RH strain.

Snails, Elimia semicarinata, infected with Proterometra macrostoma were collected monthly in 1990 and 1991 from North Elkhorn Creek near Lexington, Kentucky, and kept on a 12:12 h light–dark cycle for 2 weeks. Cercariae emerging from snails were classified into 8 strains (I–VIII) based on differences in number and distribution of spined and spineless papillae on the tail. Cercariae also had unique patterns of emergence, swimming behaviour and infectivity in 4 species of sunfish. Of 513 infected snails collected in May, 339 had pure infections with the strain frequencies (% of 339): I, 46·6; II, 7·7; III, 12·1; IV, 8·8; V, 0·6; VI, 2·7; VII, 11·8; VIII, 9·7. In the multiple infections, 159 snails shed 2 strains, 14 shed 3, and 1 snail shed 4 strains simultaneously. A comparison of sunfish and parasite populations in Kentucky, Ohio and Michigan indicated that strain frequency in P. macrostoma is regulated by the species composition of the sunfish population.

Echinococcus granulosus antigen B (AgB) is encoded by a gene family and is involved in the evasion of the host immune response. E. granulosus exists as a number of strains (G1–G10) that differ in biological characteristics. We used PCR-SSCP followed by DNA sequencing to evaluate sequence variation and transcription profile of AgB in 5 E. granulosus strainsNucleotide sequence data reported in this paper are available in the GenBankTM database under the Accession numbers AY569341-AY569371, AY159484, AY159485, AY608606, AY608607, AY614001.. Twenty-four genomic sequences were isolated and clustered in 3 groups related to 2 of the 5 reported AgB genes. AgB4 genes were present in almost all strains, whereas AgB2 were present as functional genes exclusively in G1/G2 cluster, and as non-functional genes in G5 and the G6/G7 cluster, suggesting inter-strain variation. The AgB transcription patterns, analysed by RT-PCR, showed that AgB2 and AgB4 genes were transcribed in G1, while only the AgB4 gene was transcribed in G7 strain. Cysts from the same strain or cluster shared more genomic and cDNA variants than cysts from different strain or cluster. The level of nucleotide and deduced amino acid sequence variation observed is higher than that reported so far for coding genes of other helminths. Neutrality was rejected for AgB2 genes. These data show the genetic polymorphism of antigen-coding genes among genetically characterized strains of E. granulosus.

Six field pea Pisum sativum (L.), lines (Holetta Local-90, 305PS210687, 061K-2P-2/9/2, 061K-2P-14/7/1, JI-898 and 304WA1101937) were screened in a greenhouse for their resistance to the pea aphid Acyrthosiphon pisum (Harris) and compared to NEP874UK line (control). The total number of progeny and the average and maximum number of nymphs produced per female during a 24-h period were significantly lower in the six lines compared to the control. The intrinsic rate of increase was also significantly higher in the control than in the other lines (except Holetta Local-90). The aphid preferred to feed on the control than on the tested lines. Line 061K-2P2/9/2 was the most resistant genotype as its height and weight were less affected by aphid attack. Based on antibiosis, antixenosis and tolerance effects, lines 061K-2P2/9/2, JI-896 and 304WA1101937T performed better against A. pisum.

To investigate the existence of inter-strain fecundity in the groundnut beetle Careydon serratus, the fecundity and larval survival of crosses of beetle strains from Bauhinia, Cassia, Piliostigma and Tamarindus were studied. The crosses produced viable eggs, but the fertility of beetles mated within strains was significantly higher than that of inter-strain matings, the former being nearly double the latter. Differences in larval mortality between the various crosses were also observed.

The northern biotype of Echinococcus granulosus occurs in North America and northern Eurasia in life-cycles involving cervids. Previously, cervid isolates of E. granulosus from North America have been characterized using molecular genetic techniques as the G8 genotype. In this study, 5 isolates of E. granulosus were collected from 4 reindeer and 1 moose in north-eastern Finland. DNA sequences within regions of mitochondrial cytochrome c oxidase I (COI) and NADH dehydrogenase I (NDI) genes and the internal transcribed spacer 1 (ITS-1) fragment of the ribosomal DNA were analysed. The mitochondrial nucleotide sequences were identical in all isolates, but high sequence variation was found in the ITS-1 region. Mitochondrial and nuclear sequences of the Finnish cervid E. granulosus and the camel strain (G6) of E. granulosus resembled closely each other. According to phylogenetic analyses, the Finnish isolates have close relationships also with the pig (G7) and cattle (G5) strains. Although some similarities were found with the previously published North American cervid strain (G8), particularly in the NDI sequence and some of the ITS-1 clones, the Finnish E. granulosus form represents a distinct, previously undescribed genotype of E. granulosus. The novel genotype is hereby named as the Fennoscandian cervid strain (G10).

Iran is an important endemic focus of cystic hydatid disease (CHD) where several species of intermediate host are commonly infected with Echinococcus granulosus. Isolates of E. granulosus were collected from humans and other animals from different geographical areas of Iran and characterized using both DNA (PCR-RFLP of ITS1) and morphological criteria (metacestode rostellar hook dimensions). The sheep and camel strains/genotypes were shown to occur in Iran. The sheep strain was shown to be the most common genotype of E. granulosus affecting sheep, cattle, goats and occasionally camels. The majority of camels were infected with the camel genotype as were 3 of 33 human cases. This is the first time that cases of CHD in humans have been identified in an area where a transmission cycle for the camel genotype exists. In addition, the camel genotype was found to cause infection in both sheep and cattle. Results also demonstrated that both sheep and camel strains can be readily differentiated on the basis of hook morphology alone.

The main characteristics of Beldi (meaning “native” in Arabic) poultry raised in rural areas were studied in the Khenifra Region through extensive surveys.

Beldi chickens have large phenotypic variability. Black, brown, grey and white colours, pure or mixed, are frequently observed in chickens' featherings while turkeys are predominantly bronze. Plumage types were fairly homogeneous in both species. Single combs and dented combs were respectively predominant in chicken hens and roosters.

Sexual maturity was reached at 154 days for roosters, 168 for hens in chicken, around 217 days for toms and 231 for turkey hens. The age at first egg averaged 5.8 months for hens and 8.4 months for turkey hens. The number of eggs laid per hen per year was 78 for chicken and 69 for turkey. Hatchability rate was 78 and 80 percent for chicken and turkeys, respectively. Diseases were the main cause of mortality, which could affect up to 77 percent of chicken flocks.

Few preliminary urgent steps for the conservation of Beldi poultry are discussed with other production improvement proposals.

Cotesia flavipes (Hymenoptera: Braconidae) is a braconid larval parasitoid that has been used in the biological control of tropical stemborers in gramineous plants. The current research status on the behavioural ecology of this parasitoid is reviewed. The stimuli involved in the location of the host-microhabitat and the behaviour on infested plants and inside stemborer tunnels are discussed. Several aspects of the host foraging behaviour on C. flavipes are discussed in relation to the ecology of the parasitoid, such as the role of learning in foraging and clutch size allocation decisions. Variation in behaviour can be an obstacle in the effective use of natural enemies in biological control. Behavioural variation may exist because individuals differ genetically in their propensity to find or accept different hosts. Individuals may also differ because they have experienced different environments (i.e. learning). The second part of this paper focuses on the intraspecific variability in G flavipes behaviour and discusses to what extent the reported plant and host specificity in C. flavipes has a genetic basis or is due to phenotypic plasticity through learning.

Several strains of Hyphomycetes fungi were assayed in the laboratory to determine their pathogenicity against second instar Chilo partellus Swinhoe larvae and fifth–sixth instar Busseola fusca Fuller larvae. Pathogenic activity to both stem borers was demonstrated with Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin. B. bassiana isolates caused mortality of 3–100% of mortality in C. partellus larvae, and 30–84% in B.fusca. Strains of M.anisopliae showed a high level of virulence for both insect pests, causing mortality levels of 65–100%. Development of fungal infection appeared to take longer in B. fusca larvae (LT50 of 6.2–13.2 days) than in C. partellus (LT50 of 1.9–5.4 days). B. bassiana isolate ICIPE 4, and M. anisopliae isolates ICIPE 18 and 30, which were effective against both stem borers, outperformed the other pathogens tested. They appear to have potential for use asmicrobial agents in the control of C. partellus and B. fusca.