Acanthodasys caribbeanensis sp. n., a new species of Thaumastodermatidae (Gastrotricha, Macrodasyida) from Belize and Panama

We describe one new species of Acanthodasys (Gastrotricha, Macrodasyida, Thaumastodermatidae) collected from sublittoral sites around Carrie Bow Cay, Belize and Isla Colón in the Bocas del Toro archipelago, Panama. Though eight species of Acanthodasys are currently recognized, no species has yet been reported from the Caribbean. Acanthodasys caribbeanensissp. n. is characterized by the lack of lateral adhesive tubes, the presence of ventrolateral adhesive tubes, and with cuticular armature in the form of both spineless and spined scales. The spineless scales are not elliptical as in other species of Acanthodasys, but are instead variable in shape and closely resemble the spineless scales of species of Diplodasys. Spined scales bear uniancres up to 50 μm long and are the largest reported in the genus. Uniancres are arranged dorsally around the mouth rim and distributed in five distinguishable columns. Adult size varies from 325-625 μm long.     

Androgen therapy in constitutional delay of growth

BACKGROUND/AIMS: Two modalities of androgen therapy prevail in the treatment of constitutional delay of growth (CDG): monthly injections of testosterone or daily tablets of the non-aromatizable oxandrolone. The present study was undertaken to prospectively compare both compounds and dose. METHODS: Thirty patients with CDG were the subjects of this study. The protocol required that they all be at age 12-14 years with a bone age delay of more than 2 'years', height less than -2 SDS and growth velocity less than -0.5 SDS. The subjects were at a Tanner stage 1 or 2 and testicular volume were no larger than 4 ml. They were randomly assigned into 3 treatment groups: group 1 patients received monthly injections of 25 mg testosterone propionate-enanthate; group 2 patients received monthly injections of 50 mg testosterone propionate-enanthate; group 3 patients received oral oxandrolone at a weekly dose of 0.7 mg/kg. Treatment was given for a period of 6 months and follow-up commenced 6 months later and yearly thereafter for 2 years. RESULTS: Height velocity and height increased significantly only in groups 2 and 3. Bone age advanced most in group 2. Puberty progressed faster in that group as compared with group 3. The predicted adult height before and 2 years after completion of treatment remained unchanged in the two testosterone groups. It increased significantly in the oxandrolone group from a mean 169.8 cm before therapy to a mean 177.5 cm 2 years after completion of therapy. Peak GH levels were significantly higher on both testosterone 50 mg and oxandrolone, as compared to pretreatment levels. The increment was significantly greater in group 2 as was the increment in serum IGF-1 and IGFBP3. CONCLUSIONS: These results imply that 6 months of testosterone injections at a dose of 50 mg, but not 25 mg, is an effective and safe treatment for patients with CDG, with no considerable impact on final height prediction. On the other hand, daily oxandrolone treatment, starting at age 12-14 years, may increase the predicted final adult height.     

Modelling the spatial configuration of refuges for a sustainable control of pests: a case study of Bt cotton

The 'high-dose-refuge' (HDR) strategy is widely recommended by the biotechnology industry and regulatory authorities to delay pest adaptation to transgenic crops that produce Bacillus thuringiensis (Bt) toxins. This involves cultivating nontoxic plants (refuges) in close proximity to crops producing a high dose of Bt toxin. The principal cost associated with this strategy is due to yield losses suffered by farmers growing unprotected, refuge plants. Using a population genetic model of selection in a spatially heterogeneous environment, we show the existence of an optimal spatial configuration of refuges that could prevent the evolution of resistance whilst reducing the use of costly refuges. In particular, the sustainable control of pests is achievable with the use of more aggregated distributions of nontransgenic plants and transgenic plants producing lower doses of toxin. The HDR strategy is thus suboptimal within the context of sustainable agricultural development.     

Olfactory orientation of the truffle beetle, Leiodes cinnamomea

Although the truffle beetle, Leiodes cinnamomea, inflicts substantial damage to the ripe stage of fruiting bodies of the economically important black truffle (Tuber melanosporum), it is not attracted by ripe truffle odours. Rather, male beetles are attracted to infested truffles only in the presence of female beetles, suggesting that the former employ a pheromone to locate truffles over short distances. In contrast, female beetles show no attraction to infested or uninfested truffles, suggesting that they employ other cues, possibly linked to odours emitted by truffles prior to the ripe stage. We hypothesize that the chemical composition of truffle volatiles changes over the life of the truffle fruiting body, being attractive to insects early on and to mammals just prior to decomposition.     

ESTABLISHING GENETIC CORRELATIONS INVOLVING PARASITE VIRULENCE

For many host-parasite interactions, virulence is necessarily affected by population densities, transmission biology of the parasite, and proliferation of the parasite at the expense of its host. Attempts to experimentally demonstrate genetic correlations involving virulence therefore need to employ protocols controlling for variation in the number of successful infections (i.e., the end-point of transmissibility). If protocols are not controlled, then correlations may be spurious, as appears to be the case in recent experimental studies by Ebert (1994) and Ebert and Magnin (1997). There is a need to explore the modes of the evolution of each of the many sequential steps in nonsymbiotic and symbiotic phases of host-parasite associations and the implication of such evolution for overall virulence. I argue that it is the interdependence of these sequential steps (and not overall virulence) that should be at the center of attempts to establish genetic correlations.     

Properties of phenylalanine transfer ribonucleic acid with modified 3''-terminal end in protein biosynthesis using a rabbit reticulocyte cell-free system: effect of the replacement of cytidine residues from the CpCpA end of tRNA by 5-iodocytidine or 2-thiocytidine.

Phe-tRNA Phe from yeast containing 2-thiocytidine or 5-iodocytidine in position 75 of the polynucleotide chain or Phe-tRNA Phe in which both positions 74 and 75 were substituted by 5-iodocytidine were investigated in the poly U-dependent polyphenylalanine synthesis on ribosomes from rabbit reticulocytes. Phe-tRNA Phe-Cps2CpA was nearly as active as the native Phe-tRNA Phe-CpCpA in the overall process. Phe-tRNA Phe-Cpi 5CpA as well as Phe-tRNA Phe-i5Cpi 5CpA were considerably less active than the native species. Investigation of individual steps of protein biosynthesis with these modified substrates revealed that the donor activity of peptidyl-tRNAs which contain 5-iodocytidine in their 3'-terminus is strongly imparied suggesting exacting structural requirements for the interaction of the CpCpA end of tRNA with the ribosomal P-site.     

Synthesis and secretion of alkaline phosphatase in vitro from first-trimester and term human placentas.

The synthesis and secretion of alkaline phosphatases in vitro by human placental tissue incubated in organ culture were studied. First-trimester placenta synthesizes and secretes two different alkaline phosphatase isoenzymes (heat-labile and heat-stable), whereas in term placenta nearly all the alkaline phosphatase synthesized and secreted is heat-stable. The specific activities of alkaline phosphatases in first-trimester and term placental tissue remain constant throughout the time course of incubation. In the media, specific activities increase with time. Hence, alkaline phosphatase synthesis seems to be the driving force for its own secretion. The rates of synthesis de novo and of alkaline phosphatases were measured. The specific radioactivities of the secreted alkaline phosphatases were higher than the corresponding specific radioactivities in the tissue throughout the entire incubation period. The intracellular distribution of the alkaline phosphatase isoenzymes was compared.     

Fragments formed by the side chain cleavage of a 20-aryl analog of 20alpha-hydroxycholesterol by adrenal mitochondria.

An analog of 20alpha-hydroxycholesterol, (20R)-20-phenyl-5-pregnene-3beta,20-diol, which is completely substituted at C-22 was prepared with radioisotopes at various positions. The analog labeled with 3H at C-M and 14C at C-4 and C-IU was converted into radioactive pregnenolone by an enzyme preparation derived from adrenal mitochondria. Cleavage of the phenyl analog labeled with 3H in the aromatic ring by the same enzyme preparation led to the formation of [3H]phenol. Using the substrate doubly labeled with 14C at C-4 and 3H in the aromatic ring, it appeared that the products of the reactions, pregnenolone and phenol, were formed in equal amounts. During incubation of the side chain labeled substrate, another labeled fragment was formed. It was identified as acetophenone, a product resulting from cleavage of the C17,20 bond. The steroidal fragment corresponding to this C8 ketone was traced using nuclear label analog. From its nonpolar chromatographic properties it appears to be a C-17-deoxy-C19 steroid.