Comparative studies of effect of auxin and ethylene on permeability and synthesis of RNA and protein

The effects of ethylene on permeability and RNA and protein synthesis were assayed over a 6 to 26 hr period in tissue sections from avocado (Persea gratissima Gaertn. F., var. Fuerte), both pulp and peel of banana (Musa sapientum L., var. Gros Michel), bean endocarp (Phaseolus vulgaris L., var. Kentucky Wonder Pole beans) and leaves of Rhoeo discolor. Ethylene had no effect on permeability in 4 of the 5 tissues, but sometimes enhanced solute uptake in banana peel; it had either no effect or an inhibitory effect on synthesis of RNA and protein in sections from fruits of avocado and banana. Auxin (α-naphthalene acetic acid) stimulated synthesis of RNA and protein in bean endocarp and Rhoeo leaf sections, whereas ethylene inhibited both basal and auxin-induced synthesis. It is concluded that in these tissues the auxin effect is not an ethylene effect.     

The Effect of Household Smoking on the Infestiveness of Di Ph Ylloboth Riu M Latum from Fish to Man

The effect of household smoking, as carried out with three commercially available smoke boxes, on the infestiveness of Diphyllo-bothrium latum was investigated. The temperature changes in fish during the smoking were measured and the effect on tapeworm larvae estimated on the basis of a lethal temperature/time exposure of 56°C/5 min. For all the boxes smoking treatments sufficient to destroy the tapeworm larvae are suggested. The obtained results confirm the conclusion, made in previous studies on other heat preparation methods of fish, that well cooked fish in which all the parts have been subjected to a 56°C/5 min. exposure is safe with regard to the risk of Diphyllobothrium latum infestation.     

Formation of Novel Polysaccharides by Bradyrhizobium japonicum Bacteroids in Soybean Nodules

Certain strains of Bradyrhizobium japonicum form a previously unknown polysaccharide in the root nodules of soybean plants (Glycine max (L.) Merr.). The polysaccharide accumulates inside of the symbiosome membrane—the plant-derived membrane enclosing the bacteroids. In older nodules (60 days after planting), the polysaccharide occupies most of the symbiosome volume and symbiosomes become enlarged so that there is little host cytoplasm in infected cells. The two different groups of B. japonicum which produce different types of polysaccharide in culture produce polysaccharides of similar composition in nodules. Polysaccharide formed by group I strains (e.g., USDA 5 and USDA 123) is composed of rhamnose, galactose, and 2-O-methylglucuronic acid, while polysaccharide formed by group II strains (e.g., USDA 31 and USDA 39) is composed of rhamnose and 4-O-methylglucuronic acid. That the polysaccharide is a bacterial product is indicated by its composition plus the fact that polysaccharide formation is independent of host genotype but is dependent on the bacterial genotype. Polysaccharide formation in nodules is common among strains in serogroups 123, 127, 129, and 31, with 27 of 39 strains (69%) testing positive. Polysaccharide formation in nodules is uncommon among other B. japonicum serogroups, with only 1 strain in 18 (6%) testing positive.     

Oxygen transport in the blood of arctic mammals: adaptation to local heterothermia

Summary The oxygen binding of whole blood from humans and two arctic mammals, reindeer and muskox, has been studied as a function of carbon dioxide and temperature. All bloods display a marked Bohr effect with Bohr coefficients in the range –0.44––0.73. The Bohr effect is more pronounced at 20°C. The temperature sensitivity of reindeer and muskox blood expressed by the apparent heat of oxygenation, H, is almost three times lower than that of human HbA under the same experimental conditions. This thermodynamic difference gives special benefits to arctic mammals with large heterothermy by safeguarding oxygen unloading at very low ambient temperatures.     

Full-length sequence and mosaic structure of a human immunodeficiency virus type 1 isolate from Thailand.

Human immunodeficiency virus type 1 isolates of envelope genotype E are contributing substantially to the global pandemic. These strains appear to be mosaics, with the gag gene from clade A and the envelope from clade E; the parental clade E strain has not been found. Here we report the first full genomic sequence of one such mosaic virus, isolate CM240 from Thailand. Multiple breakpoints between the two parental genotypes have been found in a CM240 virus. The entire gag-pol region and most, if not all, of the accessory genes vif, vpr, tat, rev, and vpu appear to derive from clade A. The genotype switches to E shortly after the signal peptide of the envelope and back to clade A near the middle of gp41; thus, the portion of the envelope that lies on the cytoplasmic side of the membrane appears to be principally derived not from clade E, as previously thought, but from clade A. Another small segment not belonging to any recognized clade and presumably also contributed by the parental E strain has been found in the long terminal repeat. It may be significant that the implied virion structure resembles a pseudotype virus with the matrix and core from one clade and the outer envelope from another. In the long terminal repeat, differences were observed between CM240 and other clades in the number of NF-kappa B binding sites, the sequence of the TATA box, and the putative secondary structure of the transactivation response region stem-loop. The mosaic structure of a CM240 virion is suggestive of phenotypic differences which might have contributed to the emergence of this variant.     

Modelling crop growth and biomass partitioning to shoots and roots in relation to nitrogen and water availability,using a maximization principle

Many crop models relate the allocation of dry matter between shoots and roots exclusively to the crop development stage. Such models may not take into account the effects of changes in environment on allocation, unless the allocation parameters are altered. In this paper a crop model with a dynamic allocation parameter for dry matter between shoots and roots is described. The basis of the model is that a plant allocates dry matter such that its growth is maximized. Consequently, the demand and supply of carbon, nitrogen, and water is maintained in balance. This model supports the hypothesis that a functional equilibrium exists between shoots and roots.This paper explains the mathematical computation procedure of the crop model. Moreover, an analysis was made of the ability of a crop model to simulate plant dry matter production and allocation of dry matter between plant organs. The model was tested using data from a greenhouse experiment in which spring wheat (Triticum aestivum L.) was grown under different soil moisture and nitrogen (N) levels.Generally, the model simulations agreed well with data recorded for total plant dry matter. For validation data the coefficient of determination (r²) between simulated and measured shoot dry weight was 0.96. For the validation treatments r² was slightly lower, 0.94. In addition to dry matter production the model succeeded satisfactorily in simulating the dry weight of different plant organs. The response of simulated root to shoot ratio to the level of soil moisture was mainly in accordance with the measured data. In contrast, the simulated ratio seemed to be insensitive to the changes in the levels soil N concentration used in the experiment.The data used in the present study were not extensive, and more data are needed to validate the model. However, the results showed that the model responses to the changes in soil N and water level were realistic and mostly agreed with the data. Thus, we suggest that the model and the method employed to allocate dry matter between roots and shoots are useful when modelling the growth of crops under N and water limited conditions.     

Mate Sampling and Assessment Procedures in Female Pied Flycatchers (Ficedula hypoleuca)

Models of mate sampling strategies predict that choosiness should decrease throughout the breeding season due to increasing costs of delaying mating. Therefore, individuals who start searching mates relatively late, should spend less time on sampling, and sample fewer candidates compared to early individuals. We observed mate searching behavior of female pied flycatchers (Ficedula hypoleuca) by radio-tracking in study areas with 6–12 unpaired males. Contrary to the prediction, the observed numbers of males sampled by the searching females increased with time, i.e. late arriving females visited more males than early arrivers. However, this seems to be due to more active sampling of males in short time by late-arriving females. The observed sampling pattern suggests some kind of comparison tactic, which seems, however, to be very variable among individual females. Mate-assessing females were characterized by a remarkably cryptic behavior, which may be 1) a way of gaining honest information about the male mating status or male/territory quality, or 2) a way of avoiding courtship costs.     

Human familial and sporadic breast cancer: analysis of the coding regions of the 17β-hydroxysteroid dehydrogenase 2 gene (EDH17B2) using a single-strand conformation polymorphism assay

17-Hydroxysteroid dehydrogenase (17HSD) is one of the key enzymes in estrogen metabolism, catalyzing the reversible reaction between estradiol and the less active estrogen, estrone. The gene encoding this enzyme, EDH17B2, has been mapped to chromosome 17, region q12–q21, in the vicinity of BRCA1, an as yet unidentified gene that appears to be involved in familial breast cancer and in familial ovarian cancer. The possibility that EDH17B2 gene is the same as BRCA1 was tested by screening for mutations in the coding regions of EDH17B2, using a polymerase chain reaction/single-strand conformation polymorphism method. An AG transition creating a new BstUI site at exon 6 was the only frequent sequence alteration found in the coding region of the gene. This mutation also led to an amino acid substitution of serine to glycine at position 312 (312^S312^G) in the 17HSD protein. Since the nucleotide change was detected both in specimens from patients with familial or sporadic cancer and in control samples, and at similar rates, this mutation appears to be of a polymorphic nature. In addition, a rare polymorphism located at intron 5 was detected. This CT substitution creates a BbvI site and is not thought to have any effect on 17HSD activity. The results indicate that there are no major alterations in the coding areas of EDH17B2 and thus studies testing the hypothesis that EDH17B2 may be the same as BRCA1 should be extended to the promoter and regulatory elements of EDH17B2.     

Wave-separation in complex systems. Application to brain-signals

A departure from single-system dynamics, that may arise in characterizing self-organized dynamics of complex systems, is dealt with by using the Karhunen-Loève expansion of the trajectory matrix to decompose an experimental signal in a sum of spectral features. For an electroencephalographic -signal, a separation of waves and extraction of additive sub-signals are achieved, each sub-signal covering a well-bounded and physiologically meaningful frequency range. From the subsignals, an attractor that vanishes on phase-randomizing the data is characterized, under conditions where none was found for the recorded signal.