1-Methyl-4-thiohistidine and Glutathione in the Developing Embryo of the Sea Urchin, Paracentrotus lividus.

4-thiohistidines occur as free amino acids in the eggs of several marine organisms, in particulary relevant concentrations in the eggs of echinoderms. Since nothing is known about their biological role or biosynthesis and metabolic fate, we measured the concentration of 1-methyl-4-thiohistidine together with the two most common small molecular weight thiols, glutathione and cysteine, during embryonic development of the sea urchin Paracentrotus lividus until the pluteus stage. The thiols were determined by high performance liquid chromatography as fluorescent derivatives of monobromobimanes. 1-methyl-4-thiohistidine and glutathione are present until the pluteus stage with an approximate ratio of 2: 1. Cysteine was detected at the blastula stage and found to increase thereafter. 1-methyl-4-thiohistidine was absent, or present in traces, in sperm and in somatic tissues of adults. It is concluded that 1-methyl-4-thiohistidine is typical of eggs and embryos and may be metabolized during metamorphosis into an as yet unknown compound.     

Parasitic Relationships between a Gall-forming Insect Tomoplagia rudolphi (Diptera: Tephritidae) and its Host Plant (Vernonia polyanthes, Asteraceae)

We studied the impact caused byTomoplagia rudolphi Lutz &Costa Lima (Diptera: Tephritidae) on the architecture, flowerproduction, seed germination and seed viability of its hostplantVernonia polyanthes Less (Asteraceae). We measured thegall influence on the number of lateral shoots, on the productionof flower heads and on seed viability. Gall formation induceda significant increase in the number of lateral shoots modifyingthe host plant normal growth pattern. Galled stems producedan average of 7.3±0.45 shoots, whereas ungalled stemsproduced 5.6±0.60 shoots. Galling also caused a significantreduction in seed viability. Seeds of galled stems had a totalpercent seed germination mean of 28.4%, while seeds of ungalledstems had a mean of 33.8%. However, flower head production andseed germination velocity were not affected by the gall. Thisstudy showed thatT. rudolphi galls influence the architectureand seed viability of its host plant. Insect galls; herbivory; herbivore impact; plant growth; Tomoplagia rudolphi ; Vernonia polyanthes     

Variation in the assessment of adequacy in cervical smears

OBJECTIVE: To assess the interobserver reproducibility of the diagnosis of 'adequacy' of cervical smears according to the Bethesda System criteria in cervical smears. STUDY DESIGN: 358 cervical smears were obtained from three Italian cytopathological centres in 1998-99. All centres provided consecutively collected smears. The cervical smears were independently and blindly assessed by four cytologists.The screening was performed using a 10x objective and an additional evaluation of the percentage of cellularity was performed using a 4x objective. RESULTS: The proportion of smears assessed by the four cytologists as 'adequate' ranged from 60% to 70%, the proportion of 'satisfactory for evaluation but limited by' ranged from 27% to 38%, and the proportion of 'inadequate smears' ranged from 2% to 4%. Full agreement in the assessment of smear adequacy was observed in 311 slides and disagreement was observed only in 47. The category 'inadequate smear' was less reliable than the other two; however, the kappa value observed was acceptable. CONCLUSION: The present study shows that it is possible to achieve a high reproducibility in the assessment of smear adequacy, at least among expert cytologists who follow the Bethesda System criteria strictly.     

Levamisole can reduce bait monopolization in wild red foxes Vulpes vulpes

1. Baits are used worldwide to deliver vaccines, contraceptives and poison to wild animal species. In carnivores, multiple bait uptake and bait monopolization by dominant individuals may reduce baiting effectiveness. This study investigated whether a conditioned‐taste‐aversion agent, levamisole, can be used to decrease bait consumption by individual wild foxes Vulpes vulpes. 2. The results indicated that after consuming levamisole‐treated baits, foxes avoided eating treated baits but consumed untreated baits. We concluded that the reduction in bait consumption was achieved through learned aversion to levamisole rather than via conditioned‐taste‐aversion to baits. Adding levamisole to baits could potentially be used to reduce bait monopolization by individual wild foxes.     

Drought impact on water use efficiency and intra‐annual density fluctuations in Erica arborea on Elba (Italy)

Erica arborea (L) is a widespread Mediterranean species, able to cope with water stress and colonize semiarid environments. The eco‐physiological plasticity of this species was evaluated by studying plants growing at two sites with different soil moistures on the island of Elba (Italy), through dendrochronological, wood‐anatomical analyses and stable isotopes measurements. Intra‐annual density fluctuations (IADFs) were abundant in tree rings, and were identified as the key parameter to understand site‐specific plant responses to water stress. Our findings showed that the formation of IADFs is mainly related to the high temperature, precipitation patterns and probably to soil water availability, which differs at the selected study sites. The recorded increase in the ¹³C‐derived intrinsic water use efficiency at the IADFs level was linked to reduced water loss rather than to increasing C assimilation. The variation in vessel size and the different absolute values of δ¹⁸O among trees growing at the two study sites underlined possible differences in stomatal control of water loss and possible differences in sources of water uptake. This approach not only helped monitor seasonal environmental differences through tree‐ring width, but also added valuable information on E. arborea responses to drought and their ecological implications for Mediterranean vegetation dynamics.     

Peculiar Epibionts in Euplotidium itoi (Ciliata, Hypotrichida)

ABSTRACT. Euplotidium itoi share with some other species of the same genus a peculiar feature: the presence of a band of particles running along the right and left borders of the cell body and forming a sort of "scarf" at the dorsal anterior end. The ultrastructural analysis, here performed, revealed that these particles (reported in the literature as extrusomes) are always external to the cell and are inserted in matching depressions on the euplotidium cortex. They are present in two different forms: type I, whose ultrastructure recalls that of bacteria, are able to reproduce by binary fission; type II are not able to divide and contain peculiar structures (a granular dome-shaped zone, a complex extrusive apparatus and a network of regularly arranged fibrils) which render them more complicated with respect to the majority of prokaryotic organisms. These observations, together with the finding that these particles contain DNA, indicate that we are dealing with epibionts, that will be referred to as "epixenosomes" (ecto-organisms), rather than extrusomes. Some ideas about the nature of "epixenosomes" and their relationship with the host cell are proposed and discussed.     

Detection of Genomic Polymorphism in Plasmodium falciparum Using an Arbitrarily Primed PCR Assay

ABSTRACT. Modifications of the arbitrarily primed polymerase chain reaction assay (i.e. a low annealing temperature and a very slow increase in the temperature during the elongation steps during the amplification cycles) allowed it to be used with the AT-rich Plasmodium falciparum DNA. The analysis of the products by polyacrylamide—urea gels, after silver staining, resulted in high resolution and sensitivity. Eighteen single and six combined pairs of arbitrary primers were tested. Two produced polymorphic patterns complex enough to differentiate between close Colombian isolates in a single assay. This method may be useful in studying the distribution and migration of strains in endemic areas, and for identifying intralaboratory cross-contamination of cultures.     

Epixenosomes: Peculiar Epibionts of the Hypotrich Ciliate Euplotidium Itoi Defend Their Host Against Predators

ABSTRACT. Euplotidium itoi harbors on its dorsal surface peculiar episymbionts (referred to as epixenosomes) equipped with a complex extrusive apparatus. In the laboratory. E. itoi stocks without epixenosomes behave and reproduce like symbiotized stocks. the hypothesis that epixenosomes play a defensive role against predators was tested by comparing the behavior of Litonotus lamella when preying upon Euplotes crassus, E. itoi without epixenosomes. and E. itoi with epixenosomes. Litonotus discharges its toxicysts upon direct-cell-to cell contact, and paralyzes the three types of prey with the same efficiency. Nevertheless, Litonotus can ingest Euplotes, Euplotidium without epixenosomes, and to a certain extent, Euplotidium with epixenosomes whose ejecting capability has been inhibited. while it never eats Euplotidium with unaltered epixenosomes. In each prey-type, about 60% of the individuals attacked by Litonotus toxicyst discharge are able to recover their normal behavior once transferred into pure sea water. This percentage for E. itoi with epixenosomes that are never eaten by the predator corresponds to the probability of survival. This probability is lower for the other two prey-types in which the prey engulfed by the predator do not have the chance to recover. These data support the hypothesis and suggest the involvement of the epixenosome's ejecting apparatus in a defensive function.     

Using DNA taxonomy to investigate the ecological determinants of plankton diversity: explaining the occurrence of Synchaeta spp. (Rotifera,Monogononta) in mountain lakes

1. The occurrence of unresolved complexes of cryptic species may hinder the identification of the main ecological drivers of biodiversity when different cryptic taxa have different ecological requirements. 2. We assessed factors influencing the occurrence of Synchaeta species (monogonont rotifers) in 17 waterbodies of the Trentino‐South Tyrol region in the Eastern Alps. To do so, we compared the results of using unresolved complexes of cryptic species, as is common practice in limnological studies based on morphological taxonomy, and having resolved cryptic complexes, made possible by DNA taxonomy. 3. To identify cryptic species, we used the generalised mixed Yule coalescent (GMYC) model. We investigated the relationship between the environment and the occurrence of Synchaeta spp. by multivariate ordination using two definitions of the units of diversity, namely (i) unresolved species complexes (morphospecies) and (ii) putative cryptic species (GMYC entities). Our expectation was that resolving complexes of cryptic species could provide more information than using morphospecies. 4. As expected, DNA taxonomy provided greater taxonomic resolution than morphological taxonomy. Further, environmental‐based multivariate ordination on cryptic species explained a significantly higher proportion of variance than that based on morphospecies. Occurrence of GMYC entities was related to total phosphorus (TP), whereas no relationship could be found between morphospecies and the environment. Moreover, different cryptic species within the same morphospecies showed different, and even opposite, preferences for TP. In addition, the wide geographical distribution of haplotypes and cryptic species indicated the absence of barriers to dispersal in Synchaeta.