Invasive Bombus terrestris (Hymenoptera: Apidae) parasitized by a flagellate (Euglenozoa: Kinetoplastea) and a neogregarine (Apicomplexa: Neogregarinorida)

The flagellate Crithidia bombi and the neogregarine Apicystis bombi have been found in individuals of Bombus terrestris, a Palaearctic species of bumble bee commercially reared and shipped worldwide for pollination services. B. terrestris has recently entered into the northwestern Patagonia region of Argentina from Chile, where it was introduced in 1998. Prevalence was 21.6% for C. bombi and 3.6% for A. bombi (n = 111). The pathogens were not detected in 441 bumble bees belonging to five of the eight known Argentine native species (Bombus atratus, Bombus morio, Bombus bellicosus, Bombus opifex, Bombus tucumanus) collected elsewhere in the country. Although the absence of natural occurrence of C. bombi and A. bombi in Argentine native bumble bees cannot be ascertained at present due to the limited surveys performed, it is important to report their detection in invasive B. terrestris. The invasion event is relatively recent and the accompanying pathogens are not species specific within the genus Bombus.     

DT56a (Femarelle): a natural selective estrogen receptor modulator (SERM)

A selective estrogen receptor modulator (SERM) is defined as a substance with dissimilar effects on different tissues: agonist in some and antagonists in others. The natural compound DT56a (Femarelle) was shown to activate estrogen receptors in human cultured female derived osteoblasts. It was also shown to relieve menopausal symptoms and to increase bone mineral density with no effect on sex steroid hormone levels and on the endometrial thickness. DT56a, similarly to estradiol-17β (E₂), stimulated the specific activity of creatine kinase (CK) in skeletal and vascular tissues of female rats, as a marker of estrogen receptor (ER) activation. However, in the uterus, CK was activated only by E₂ but not by DT56a. In order to prove that DT56a is a SERM, we examined the mutual interaction between DT56a and E₂, at supra physiological doses, in different tissues in both intact and ovariectomized female rats, as well as in human cultured vascular and bone cells. Administration of DT56a or E₂ stimulated CK in all tissues tested, but when given simultaneously, in intact immature female rats, DT56a completely abolished E₂ stimulation of CK in all organs except in the diaphyseal bone where the inhibition was partial. In ovariectomized female rats, DT56a abolished E₂'s stimulation of CK in diaphyseal bone, thymus, uterus and pituitary but caused a partial inhibition in aorta, left ventricle and epiphyseal cartilage. In human bone cells E₂ stimulation of CK, of alkaline phosphatase (AP) activity and of DNA synthesis was completely abolished by DT56a in post-menopausal cells and partially inhibited in pre-menopausal cells. In human vascular cells, inhibition of DNA synthesis by E₂ was completely abolished by DT56a and E₂-induced CK was partially inhibited by DT56a. The results support the finding that DT56a is a SERM; it stimulated different parameters similar to E₂, but when given simultaneously, at supra physiological doses, inhibited these E₂'s effects. Further investigations regarding intra and extra cellular mechanism of action of DT56a are currently performed.     

Ecology of Potamanthus myops (Walsh) (Ephemeroptera: Potamanthidae) in a Michigan stream (USA)

The ecology of Potamanthus myops (Potamanthidae) was examined for a one year period in a central Michigan fourth order stream. Lowest nymphal densities (4.7 m^-2) occurred in mid-summer after adult emergence, while highest densities were found during late summer and fall (68.0 m^-2 and 66.2 m^-2) after the new cohort had hatched. Biomass was the inverse of density with highest values, 67.7 mg m^-2, just prior to peak adult emergence in June and lowest in late summer (16 mg m^-2). Nymphs maintained a contagious spatial distribution with k values ranging between 0.19 and 1.40. P. myops nymphs fed mostly on detritus (96.8%), placing them in the collector-gatherer functional group. Nymphs were always found in erosional zones associated with rock substrate. Nymphs used their mandibular tusks for positioning themselves beneath rocks, while also appearing to use them for defensive purposes.     

Brachymeria pandora (Crawford) (Hymenoptera: Chalcididae) as a New Parasitoid of Thyrinteina leucocerae (Rindge) (Lepidoptera: Geometridae) in Brazil

This is the first report of Brachymeria pandora (Crawford) (Hymenoptera: Chalcididae)-parasitizing pupae of the eucalyptus defoliator Thyrinteina leucocerae (Rindge) (Lepidoptera: Geometridae) in Brazil.     

The apolipoprotein (a) gene: a transcribed hypervariable locus controlling plasma lipoprotein (a) concentration

Lipoprotein(a) [Lp(a)] is a quantitative trait in human plasma. Lp(a) consists of a low-density lipoprotein and the plasminogen-related apolipoprotein(a) [apo(a)]. The apo(a) gene determines a size polymorphism of the protein, which is related to Lp(a) levels in plasma. In an attempt to gain a deeper insight into the genetic architecture of this risk factor for coronary heart disease, we have investigated the basis of the apo(a) size polymorphism by pulsed field gel electrophoresis of genomic DNA employing various restriction enzymes (SwaI, KpnI, KspI, SfiI, NotI) and an apo(a) kringle-IV-specific probe. All enzymes detected the same size polymorphism in the kringle IV repeat domain of apo(a). With KpnI, 26 different alleles were identified among 156 unrelated subjects; these alleles ranged in size from 32kb to 189kb and differed by increments of 5.6kb, corresponding to one kringle IV unit. There was a perfect match between the size of the apo(a) DNA phenotypes and the size of apo(a) isoforms in plasma. The apo(a) DNA polymorphism was further used to estimate the magnitude of the apo(a) gene effect on Lp(a) levels by a sib-pair comparison approach based on 253 sib-pairs from 64 families. Intra-class correlation of log-transformed Lp(a) levels was high in sib-pairs sharing both parental alleles (r = 0.91), significant in those with one common allele (r = 0.31), and absent in those with no parental allele in common (r = 0.12). The data show that the intra-individual variability in Lp(a) levels is almost entirely explained by variation at the apo(a) locus but that only a fraction (46%) is explained by the DNA size polymorphism. This suggests further heterogeneity relating to Lp(a) levels in the apo(a) gene.     

Energetics of offspring production: a comparison of a marsupial (Monodelphis domestica) and a eutherian (Mesocricetus auratus)

This study compares the energetic cost of reproduction during gestation and lactation of a eutherian, the golden hamster (Mesocricetus auratus), and a similar-sized (60–120 g) marsupial, the gray short-tailed opossum (Monodelphis domestica). Food consumption was monitored in 20 reproductively active (RA) opossums and 16 RA hamsters from conception to weaning and at equivalent intervals in 19 non-reproductive (NR) opossums and 21 NR hamsters, all maintained within their zone of thermoneutrality (30 °C). Total energy assimilated from conception to weaning [opossums: 1261.3 ± 28.0 Kcal (1 Kcal = 4.1868 J) and hamsters: 1647.5 ± 60.6 Kcal] was positively correlated with litter size and mass per young in both species. Maternal mass-specific assimilated energy was significantly greater in hamsters than in opossums during gestation (P < 0.001), but not during lactation or from conception to weaning (P > 0.05). Efficiency of offspring production (energy stored in young/incremental energy in RA females) was higher in hamsters than in opossums and, in both species, it was higher during lactation than in gestation. The energetic cost of reproduction (per young per day) was higher in hamsters than in opossums. The marsupial mode of reproduction, as seen in opossums, yields young at lower cost but requires a longer reproductive period than is the case for a similar-sized eutherian. Accepted: 8 September 1998     

Lasioglossum (Dialictus) tenax (Sandhouse) (Hymenoptera: Halictidae) as a solitary sweat bee

Summary Nine nests ofLasioglossum (Dialictus) tenax were excavated near Calgary, Alberta, Canada over a time period encompassing the entire brood production period in 1988. Each nest contained a maximum of one active adult female, nest productivity peaked in mid July, protandry was noted and no significant size difference between foundresses and the earlier emerging females was detected. These data suggest that this species is solitary. These results are compared with data for the sympatrically nesting eusocial speciesL. (D.) laevissimum.     

Insertion of a magnesium(II)-octacarboranyl(hexylsulfanyl) porphyrazine into liposomes: a physico-chemical study

The synthesis, characterization and liposome insertion of a novel magnesium(II) carboranyl-porphyrazine, i.e. [2,3,7,8,12,13,17,18-octakis-(1,2-dicarba-closo-dodecaboranyl)-hexylthio-5,10,15,20-porphyrazine]magnesium(II) complex, MgHECSPz, are described. MgHECSPz was designed to improve the potentiality in multiple approach anticancer therapy. Liposomal formulations with different surface charge were prepared as delivering agents. The obtained loaded vectors were characterized by DLS, SAXS, SANS and zeta potential measurements in order to define the overall properties and structural details of loaded liposomes.     

The biology of a giant dung-beetle (Heliocopris dilloni) (Coleoptera: Scarabaeidae)

Heliocopris dilloni is the largest dung-beetle found in the Tsavo National Park, Kenya, which during the biannual rainy seasons comprises the most important agency of elephant dung removal. The species is shown to exhibit considerable morphological variation. The mode of construction of the brood chamber is described together with details of development from egg to pupa. It is suggested that the depth to which these beetles burrow is related to avoiding the extreme climate near the surface and to predator avoidance.     

Isolation of apolipoprotein(a) from lipoprotein(a)

An easy method was developed for the rapid and selective isolation of apo(a) from human plasma Lp(a). This procedure was applied to a "low density" Lp(a) subspecies (usually found in the density interval 1.050 to 1.070 g/ml) from a single individual whose apo(a) was of a size smaller than apoB-100. After reduction with 0.01 M dithiothreitol, apo(a) was separated from the Lp(a) particle by rate zonal centrifugation on a 7.5-30% NaBr density gradient. Two completely water-soluble products were recovered: apo(a), which contained less than 1% each of phospholipid and cholesterol, remained at the bottom of the gradient, and a lipid-rich floating LDL-like particle which contained apoB but not apo(a) and which we referred to as Lp(a-). The separation of these two components was also achieved by subjecting reduced Lp(a) to electrophoresis on 2.5-16% polyacrylamide gradient gels. However, dissociation of reduced Lp(a) could not be achieved by gel filtration in either low or high salt solutions. These observations indicate that apo(a) is associated to Lp(a) by non-covalent interactions in addition to its disulfide linkage to apoB. The latter is sensitive to chemical reduction whereas the former are broken through the action of a gravitational or electrical field.     

Scymnodon plunketi (Waite, 1910): a junior synonym of Scymnodon macracanthus (Regan, 1906) (Somniosidae: Elasmobranchii)

The taxonomic status and validity of Scymnodon macracanthus (Regan, 1906) and Scymnodon plunketi (Waite, 1910) are revised in light of new material from the Southern Pacific and Indian Oceans. Despite being historically accepted as distinct taxa, recent studies suggested the possibility that these species could represent a single taxon. Morphometrics, meristics and morphology of dermal denticles show that S. plunketi is indeed a junior synonym of S. macracanthus. Previous distinctive characters proved to be the result of intraspecific variation. S. macracanthus is therefore redescribed including an updated comparative diagnosis for the genus Scymnodon in the family Somniosidae.