26,26,26,27,27,27-hexafluoro-1,25-dihydroxyvitamin D3: a highly potent, long-lasting analog of 1,25-dihydroxyvitamin D3

A new fluoro analog of 1,25-dihydroxyvitamin D3, i.e., 26,26,26,27,27,27-hexafluoro-1,25-dihydroxyvitamin D3, has been compared with the native hormone, 1,25-dihydroxyvitamin D3, in its biological potency, duration of action, and binding to the vitamin D transport protein and intestinal receptor protein. The fluoro analog is about 5 times more active than the native hormone in healing rickets and elevating serum inorganic phosphorus levels of rachitic rats. It is about 10 times more active than 1,25-dihydroxyvitamin D3 in increasing intestinal calcium transport and bone calcium mobilization of vitamin D-deficient rats fed a low-calcium diet. Furthermore, the higher biopotency is manifested in animals after oral dosing. Of great importance is that the action of the fluoro analog is longer lasting than that of 1,25-dihydroxyvitamin D3. This is especially apparent in the elevation of serum phosphorus and bone mineralization responses. The fluoro analog is only slightly less competent than 1,25-dihydroxyvitamin D3 in binding to the vitamin D transport protein in rat blood, and is one-third as competent as 1,25-dihydroxyvitamin D3 in binding to the chick intestinal cytosol receptor for 1,25-dihydroxyvitamin D3. These results suggest that the basis for increased potency of this analog is likely the result of less rapid metabolism.     

Induced plasmon mutations affecting the growth habit of peanuts, A. hypogaea L.

The effectiveness of the acridines ethidium bromide (EB) and acriflavine in inducing plasmon mutations was compared with the alkylating agents ethyl methanesulphonate (EMS) and diethyl sulphate and to γ-rays. The growth habit (trailing versus bunch) of peanuts (A. hypogaea), controlled by geniccytoplasmic interactions, was utilized. Breeding tests distinguishing nuclear from plasmon mutations were developed and are described in detail. Plasmon mutations were induced, but there were differences in mutation yields between the cultivars and the mutagens.In the trailing line, TBR[V4], 135 independent bunch mutations (in 1804 M₂ families) were recovered: 28 bred true while 97 continued to segregate into M₃ and M₄. Of the 28, 14 were nuclear from an Hb to an hb allele while 14 were in the plasmon. Of the latter, 6 were induced by EMS, 7 by γ-rays and 1 by acriflavine. Somatic segregation of heteroplasmons, i.e. more plasmon mutations, could be responsible for many of the mutations that continued to segregate, but in some cases chromosomal aberrations might be involved.In the bunch cultivars there were 32 independent trailing mutations (in 3895 M₂ families), one bred true for trailing, while the others continued to segregate into M₃ and M₄. Plasmon mutations could not be ascertained because of the continuing segregations, but these mutations manifested sorting out of heteroplasmons.     

Soil macrofauna diversity as a key element for building sustainable agriculture in Argentine Pampas

The agricultural activity in the Argentine Pampas, characterized by an important trend towards no-till soybean monocropping, has completely transformed the original Pampas landscape into a monotonous scenario with a continuous succession of farms of very low crop diversity. This process has led to soil physical, chemical and biological degradation in those systems. The increase of crop rotation rates in no-till and reduced tillage systems has been proposed as an alternative with reduced negative impact on soils in the context of conventional agriculture. On the other hand, extensive organic farming is also suggested as an alternative to high-input agriculture systems. In this article, we aim to explore how different variations of farming practices and systems impact soil macrofauna, along an edaphoclimatic gradient in the Pampas region. We studied the following systems: natural grassland (Gr) as indicator of the original community, extensive organic farming (Org), conventional agriculture with no-tillage and three crop rotation levels (Nt-R1, Nt-R2 and Nt-R3), and reduced tillage with two levels of crop rotation (Til and Til-R). We assessed soil macrofauna, with emphasis on earthworm, beetle and ant communities; and soil physical and chemical properties. Macrofaunal taxa composition was significantly affected by both management systems and edaphoclimatic conditions. The Gr community had pronounced differences from all the agricultural systems. The earthworm community from Gr had distinctive features from those of most agricultural systems, with Org and Nt-R3 being the most similar to Gr in native and exotic earthworm species, respectively. The beetle community in Org was the most different one, and the communities from the other systems did not show a pattern related to management. Ant community composition was not determined by management systems, but it was affected by edaphoclimatic conditions. All the studied macrofauna groups had a significant co-variation with soil physical and chemical properties, showing that both the characteristics of each soil relative to the geographic location and the effect of management on abiotic soil attributes have an important effect on soil macrofauna. This study confirms that biodiversity is being lost in Pampas soils, which implies a possible threat to the soil capacity to perform the processes that sustain soil functioning and hence plant productivity. Further considerations about the sustainability of the current agricultural model applied in the Argentine Pampas are needed.     

Studies on the tardigrades. 3. Fine structure of the esophagus of Milnesium tardigradum Doyère

A fine structural analysis of the esophagus of the tardigrade Milnesium tardigradum Doyère is presented. This foregut structure exhibits pronounced secretory activity with discharge of accumulated material by fusion of secretory vesicles with luminal and lateral surfaces of the esophageal cells. The possible function of this secretory material as well as the organization of esophageal cells and structure of the cuticular lining are discussed.     

The effect of progesterone on the activity-wheel running of ovariectomized rats

Progesterone treatment failed to significantly depress activity-wheel activity elicited by food deprivation in either ovariectomized or ovariectomized estrogen-treated rats. These results indicate: (1) that the lack of effect of progesterone on the activity of ovariectomized rats is not due only to their already low level of activity; and (2) that the depressant effect of progesterone on activity in the estrogen-treated ovariectomized rat is, to a large extent, a specific inhibition of estrogen facilitation of activity, rather than a nonspecific activity depressant effect.     

Dephosphorylation and activation of acetyl-CoA carboxylase by phosphorylase phosphatase

Acetyl-CoA carboxylase from rat epididymal fat tissue is activated by phosphorylase phosphatase, a reaction which is inhibited by phosphatase inhibitor-1. This activation is accompanied by a corresponding loss of ³²P from the labelled enzyme. These results establish that dephosphorylation of the enzyme causes its activation.     

Chaetomium globosum for reducing primary inoculum of Diaporthe phaseolorum f. sp. meridionalis in soil-surface soybean stubble in field conditions

The potential of an antibiotic-producing isolate of Chaetomium globosum (CgA-1) to suppress Diaporthe phaseolorum f. sp. meridionalis (Dpm) in soybean stubble was studied in field microplots of no-tillage, minimum-tillage, and shallow plowing. Mature soybean stems colonized in vitro with Dpm were spread on the soil surface and C. globosum ascospore suspension, without nutrient supply, was sprayed over the entire plot prior to any tillage operation. Perithecial formation and survival of Dpm in soybean stems, concomitantly with colonization by C. globosum, were monitored for a 180-day period (mid-autumn through winter and mid-spring), which is the normal interval between soybean harvest and sowing. The proportion of soybean stem segments occupied by Dpm and number of perithecia formed decreased linearly with time and showed a strong negative correlation with increase in the occupation by C. globosum. At the end of the study, which coincided with the soybean sowing season, the soybean stubble was free from viable Dpm and was colonized by C. globosum. The effectiveness of C. globosum in eliminating the pathogen from surface-borne residue or harrowed-in residue was similar but much slower than in the shallow-plowed microplots. C. globosum successfully competed with major interfering fungi such as, Trichoderma, Nigrospora, and Fusarium in colonizing the soybean stems above and under the soil surface. The data provide strong evidence for use of the antibiotic-producing isolate of C. globosum to control soybean stem canker disease.     

Antigen-antibody reaction by monolayer technique experiments with rabbit IgG antibody and its fragment.

With the monolayer technique, values of about 99.7 Å for rabbit anti-egg albumin IgG antibody, and about 58.9 Å for Fab fragment of IgG were obtained as the thickness of the adsorbed antibody layer. As these values determined in the saturated state were confirmed, it may be reasonable to assume that they correspond approximately to the long axis of both molecules.     

Structural and biochemical insights into the substrate-binding mechanism of a novel glycoside hydrolase family 134 β-mannanase

Mannan is one of the major constituent groups of hemicellulose, which is a renewable resource from higher plants. β-Mannanases are enzymes capable of degrading lignocellulosic biomass. Here, an endo-β-mannanase from Rhizopus microsporus (RmMan134A) was cloned and expressed. The recombinant RmMan134A showed maximal activity at pH?5.0 and 50?°C, and exhibited high specific activity towards locust bean gum (2337?U/mg). To gain insight into the substrate-binding mechanism of RmMan134A, four complex structures (RmMan134A–M3, RmMan134A-M4, RmMan134A-M5 and RmMan134A-M6) were further solved. These structures showed that there were at least seven subsites (?3 to +4) in the catalytic groove of RmMan134A. Mannose in the ?1 subsite hydrogen bonded with His113 and Tyr131, revealing a unique conformation. Lys48 and Val159 formed steric hindrance, which impedes to bond with galactose branches. In addition, the various binding modes of RmMan134A–M5 indicated that subsites ?2 to +2 are indispensable during the hydrolytic process. The structure of RmMan134A–M4 showed that mannotetrose only binds at subsites +1 to +4, and RmMan134A could therefore not hydrolyze mannan oligosaccharides with degree of polymerization ≤4. Through rational design, the specific activity and optimal conditions of RmMan134A were significantly improved. The purpose of this paper is to investigate the structure and function of fungal GH family 134 β-1,4-mannanases, and substrate-binding mechanism of GH family 134 members.