Arsenic in orchard and potato soils and plant tissue

Summary The total and water soluble arsenic contents of orchard and potato field soils are significantly higher where arsenic has been applied. Orchards with a record of past and present applications show average values as high as 99.57 ppm total arsenic and 1.99 ppm water-soluble arsenic. Orchards with a low or no arsenic application show 27.21 ppm total and 0.20 ppm water-soluble arsenic. Potato fields situated on ex-orchard plantings have an average of 38.70 ppm total and 0.32 ppm water-soluble arsenic, whereas those on non-orchard soils showed values of 9.63 and 0.04 ppm respectively. Highest soil arsenic concentrations were found in the 0–10 cm surface layer and at a distance of one meter from the tree trunk. In plant tissue the apple leaf, peel and pulp all were significantly higher for recently arsenic treated orchards, while only the apple pulp showed significance where applications had been discontinued for the past 10–15 years. Potato leaf and peel were significantly higher in arsenic on exorchard soil while the pulp was not.     

Investigation of the operational stabilities and kinetics of glucoamylase immobilized on alkylamine derivatives of titanium(IV)-activated porous inorganic supports

Glucoamylase (exo-1,4-α-d-glucosidase, EC 3.2.3.1) was coupled to several porous silica matrices by an improved metal-link/chelation process using alkylamine derivatives of titanium(IV)-activated supports. In order to select the titanium activation procedure which gave stable enzyme preparations, long-term stability tests were performed. The immobilized glucoamylase preparations, in which the carrier was activated to dryness with a 15% w/v TiCl₄ solution, displayed very stable behaviour, with half-lives of ～60 days. The optimum operating conditions were determined for these preparations. There are significant differences between the behaviour of the immobilized enzyme and the free enzyme. The apparent K_m increased on immobilization due to diffusional resistances. The pH optimum for the immobilized preparation showed a slight shift to acid pH relative to that of the soluble enzyme. Also, the optimum temperature descreased to 60°C after immobilization. In order to test Michaelis-Menten kinetics at high degrees of conversion, time-course analysis of soluble starch hydrolysis was performed. It was observed that simple Michaelis-Menten kinetics are not applicable to the free/immobilized glucoamylase-starch system at high degrees of conversion.     

The species-area relation III. A third model for a delimited community

Summary A mathematical model of the species-area relation is described for a group of limited species. This model is a modification of that proposed earlier (Kobayashi, 1975), being assumed that the limited species are expected to occur in a habitat under consideration. The model equation gives a sigmoid species-log area curve implying that few rare species are found in a group of species. The good agreement between observation and this model is exemplified with the data of plant and arthropod communities. The implication of parameters involved are examined in connection with those of the preceding model, and the underlying ecology of the model is discussed. Contribution from the Laboratory of Applied Zoology, Yamagata University, No. 83.     

PHYLOGENETIC RELATIONSHIPS OF CAULERPA (CHLOROPHYTA) BASED ON COMPARATIVE CHLOROPLAST ULTRASTRUCTURE1,2

The ultrastructure of chloroplasts from 28 of the 73 species of Caulerpa Lamouroux (Chlorophyta, Caulerpales) has been studied to aid in interpreting phylogenetic relationships among the 12 recognized sections. Variations of systematic value include pyrenoid occurrence and fine structure, thylakoid architecture and amount of photosynthate storage. Comparisons of field and culture specimens indicate these characters are consistent. Chloroplast thylakoids are grouped into bands, with the distribution of bands differing among species. In the most common arrangement, bands are evenly distributed throughout the chloroplast. A few species show lateral displacement of bands whereas others have a majority of bands arranged at one end of the chloroplast. Starch is stored cither as one or two large grains (> 1 μm diam.) or numerous small grains (< 0.5 μm diam.). Electron-transparent regions are common in other species in which chloroplasts rarely store starch. Simple, embedded pyrenoids are present in several species of section Sedoideae. An opaque region occurs in chloroplasts of C. elongata which may represent an intermediate stage in the evolutionary loss of the pyrenoid. It is suggested that the chloroplast of Caulerpa evolved, from a large, complex, pyrenoid-containing organelle housing both photosynthetic and amylogenic functions, to a small, structurally simpler one, specialized for photosynthesis alone. A phylogeny of the 12 sections of Caulerpa is constructed, based on chloroplast evolution which agrees with an earlier morphology-based hypothesis on the origin and evolution of Caulerpa.     

Activity of phosphorylase in Solanum tuberosum during low temperature storage

Changes in the activity of phosphorylase were measured during storage of potatoes at + 2° when the sugar content rises rapidly and subsequently at + 10° when the accumulated sugar is converted mainly to starch. The observed changes were relatively small and could not be related to any of the components of the phosphorylase system, which was shown to be complex.     

The α(1–4)(1–6) glucans from sweet and normal corns

After removal of granular starch at low centrifugal force, the centrifugation, at increasing forces, of aqueous extracts of su₁ corn gave a series of α-glucan precipitates that contained amylose. The amylose content decreased as the force increased. In contrast, in normal corn all the α-glucan precipitated as starch granules at low forces. In the sweet corn precipitates, apart from the granular starch, the branched α-glucan was phytoglycogen. The MW of this decreased as the proportion of amylose decreased. It appears that, as well as starch granules and soluble phytoglycogen, sweet corn contains granules, smaller than starch, of a range of sizes, and these are made up of phytoglycogen and amylose. As granule size decreases, so does the MW of the phytoglycogen and the content of amylose. A method of quantitative extraction of starch giving minimal depolymerization is described. The isopotential iodine absorption of a quantitative extract of sweet corn flour indicated that the total ratio of linear (amylose) fraction to branched (amylopectin + phytoglycogen) fraction was near the normal value of 1:4.     

Blood protein polymorphisms in the donkey (Equus asinus)

Transferrin, albumin, 6-phosphogluconate dehydrogenase and vitamin D-binding protein polymorphisms were detected in 242 feral and domesticated Australian donkeys by polyacrylamide gel electrophoresis, starch gel electrophoresis, autoradiography, immunoblotting with specific antisera and activity staining. All four TF and two ALB variants were donkey specific while only one of the PGD variants was donkey specific. The two GC variants were electrophoretically identical to the Equus caballus F and S proteins. Available evidence suggested that the TF, ALB, PGD and GC systems are controlled by co-dominant alleles with frequencies of the most common alleles of each system being 0·831, 0·946, 0·957 and 0·861 respectively. Glucose phosphate isomerase and plasminogen were monomorphic in the Australian population of donkeys.     

Glycoalkaloid Profile in Potato Haploids Derived from Solanum tuberosum–S. bulbocastanum Somatic Hybrids

Cultivated and wild potato species synthesize a wide variety of steroidal glycoalkaloids (GA) that may affect either human health or biotic stress resistance. Therefore, GA composition must be a major criterion in the evaluation of breeding products when species genomes are merged and/or manipulated. This work reports the results of GA analysis performed on unique haploid (2n=2x=24) plants obtained from tetraploid (2n=4x=48) Solanum bulbocastanum–S. tuberosum hybrids through in vitro anther culture. Glycoalkaloids were extracted from tubers and analyzed by HPLC. Haploids generally showed the occurrence of parental GA. However, in several cases loss of parental GA and gain of new GA lacking in the parents was observed. It may be hypothesized that new GA profiles of our haploids is the result of either genetic recombination or combinatorial biochemistry events. To highlight differences between haploids and parents, soluble proteins and antioxidant activities were also determined. Both were always higher in haploids compared to their parents. The nature of the newly formed GAs will be further investigated, because they may represent new metabolites that can be used against pest and diseases, or are useful for human health.     

不同海拔地区种植的水稻次库碳水化合物含量的比较

在品种、土壤、底肥和追肥等一致的情况下,对三个不同海拔地区种植的水稻的次库(茎+叶鞘)中碳水化合物含量作了比较,结果表明:齐穗和黄熟期次库中总糖或淀粉含量均随海拔增高而增加。但在黄熟期,高海拔地区次库的总糖或淀粉含量比齐穗期的增加,而低海拔地区次库的总糖或淀粉含量则比齐穗期的降低。 齐穗期时,次库的淀粉含量随施用的氮素肥量的增加而降低。在黄熟期,温凉稻作区水稻次库的淀粉含量均随氮素底肥施用量的增加而增加,低熟地区水稻次库的淀粉含量则趋于一致,不过不同地区相比各处理次库的淀粉含量均因海拔增高而增加。 不同时期的氮素追肥使齐穗期次库淀粉含量因追肥时间推迟而增加,唯元江晚穗肥处理的低于中穗肥处理的。黄熟期因追肥时间提早而次库的淀粉含量增加,但元江以早穗肥处理的次库淀粉含量最低。与齐穗期相比时,低海拔地区的各个处理,其次库的淀粉含量均减低,但高海拔的昆明温凉稻作区,施早和中穗肥的水稻,在黄熟期次库的淀粉含量反而增高。还可以看出水稻种植地海拔越高,其次库淀粉含量对追肥时间越敏感。 基于水稻次库中淀粉含量对氮素肥料的反应,就三地气候条件讨论了上述的差异。     

Effects of relaxation of gluten network on rehydration kinetics of pasta

The aim of this study was to investigate the effects of the relaxation of the gluten network on pasta rehydration kinetics. The moisture content of pasta, under conditions where the effects of the diffusion of water on the moisture content were negligible, was estimated by extrapolating the average moisture content of pasta of various diameters to 0?mm. The moisture content of imaginary, infinitely thin pasta did not reach equilibrium even after 1?h of rehydration. The rehydration of pasta made of only gluten was also measured. The rate constants estimated by the Long and Richman equation for both the pasta indicated that the rehydration kinetics of infinitely thin pasta were similar to those of gluten pasta. These results suggest that the swelling of starch by fast gelatinization was restricted by the honeycomb structural network of gluten and the relaxation of the gluten network controlled pasta rehydration kinetics.