Synthesis of an Asymmetrically Substituted AZA Crown Ether as Metal and Amino Acid Binding Site in DNA Conjugates

Abstract

Crown ether 4 as a receptor core for protonated primary amines such as amino acids has been synthesized and incorporated into oligodeoxynucleotides as dangling ends.     

Histochemical observations on the crown skin of male baya: Lipids,lipase and phosphomonoesterases

Histochemical studies on localisation of lipids, lipase and phosphomonoeste-rases in the crown skin of male baya during non-breeding and breeding seasons were carried out. The results indicated a high turnover rate for lipid synthesis and its utilisation, increased acid and alkaline phosphatase activities in the crown skin of breeding male baya as compared to that in non-breeding season. It is surmised that crown skin of male baya becomes metabolically hyperactive during breeding season aiding processes such as cell growth and proliferation, keratinization and production of coloured feathers related to breeding.     

Mass-spectrometric quantitation of cytokinins in tobacco crown-gall tumours induced by mutated octopine Ti plasmids of Agrobacterium tumefaciens

The levels of the major cytokinins, zeatin, zeatin riboside, zeatin riboside-5-monophosphate and zeatin-7-glucoside were measured in tobacco (Nicotiana tabacum L.) crown-gall tissues carrying insertion and deletion mutations in the T-DNA. Measurements were made by combined gas chromatography-mass spectrometry using selected ion monitoring with ¹⁵N- and ²H-labelled internal standards. The results demonstrate that, relative to wild-type tumour tissue, cytokinin levels are considerably elevated in tissues lacking functional T-DNA auxin-biosynthetic genes. From a detailed analysis of the major cytokinin metabolites it is concluded that a reduction in the extent of cytokinin degradation via N⁶-side-chain cleavage is an important factor leading to increased cytokinin levels in these tissues.Abbreviations IAA indole-3-acetic acid - SIM selected ion monitoring - Z zeatin - [7G]Z zeatin-7-glucoside - [9R]Z zeatin-9-riboside - [9R-5P]Z zeatin riboside-5-monophosphate     

Nodulation of lucerne (Medicago sativa L.) in an acid soil: Effects of inoculum size and lime-pelleting

The effects of inoculum level and lime-pelleting were studied in an acid soil with respect to the nodulation and growth of lucerne (Medicago sativa cv Resis) and the population dynamics of Rhizobium meliloti. In small root-boxes (rhizotrons), the in-situ survival of inoculated rhizobia was studied in the micro-environment around the seed for a period of 12 days after sowing. During the initial 24 hours, a strong increase in rhizobial numbers was measured, concomitantly with the development of roots. As a result of lime-pelleting, rhizobial numbers were higher only at 3 days after sowing (P<0.05). Later, this difference diminished steadily. Addition of lime did not increase the adhesion of the rhizobia to the seedling tap root. Plant responses to inoculation were studied in pots. To obtain optimal nodulation, the soil had to be neutralized around the seed with lime and at least 10⁵ cells of R. meliloti were required. With more than 10⁵ rhizobia per seed, lime-pelleting increased the number of crown-nodulated seedlings from 24% to 77%. Higher numbers of rhizobia could not compensate the effect of lime. A strong correlation was found between crown nodulation, nitrogen content and dry weight of the shoots.     

Interactions Between Calonectria crotalariae and Heterodera glycines on Soybean

The interactions of Heterodera glycines at four egg inoculum levels (0, 100, 1,000, and 10,000 per pot) and three cyst levels (0, 100, and 200 per pot) and Calonectria crotalariae at 500, 5,000, and 50,000 microsclerotia per pot were evaluated on soybean. At the two lowest nematode egg levels, the presence of C. crotalariae did not affect nematode reproduction. At 10,000 eggs per pot, however, nematode reproduction was increased significantly at each microsclerotial level. The increase in nematode reproduction was stepwise at 500 and 5,000 microsclerotia per pot but declined at 50,000 microsclerotia per pot. Similar results were obtained when cysts rather than eggs were used as nematode inoculum. The nematode x fungus interaction significantly affected 60-day plant growth parameters of both Lee 74 and Centennial soybean. The nematode x fungus interaction was antagonistic to plant roots and significantly influenced root injury ratings. The presence of C. crotalariae in tissues of stock plants or plants used as race differentials did not alter the analysis of this population as race 3.     

Negritos, Australian aborigines, and the "proto-sundadont" dental pattern: the basic populations in east Asia, V.

Five evolutionarily significant dental traits were identified from a B-square distance analysis of nine crown characters recorded for several populations of East Asia and Oceania. Intergroup variation in these traits distinguishes three major divisions of the Mongoloid dental complex: sundadonty, sinodonty, and the dental pattern of Australian Aborigines. The Australian crown features may be characterized as having high frequencies of evolutionarily conservative characters. Negritos, one of the probable representatives of indigenous inhabitants of Southeast Asia who may have shared a common ancestor with Australians, possess the more derived sundadont dental pattern. As far as the five crown traits treated here are concerned, Australian dental features may be described as conforming to a "proto-sundadont" dental pattern, applying Turner's terminology. This pattern may represent a microevolutionary step prior to the emergence of the sundadont and sinodont patterns.     

Functional analysis of a complex oncogene arrangement in biotype III Agrobacterium tumefaciens strains

The ubiquitous grapevine-associated octopine/cucumopine Ti plasmids of biotype III Agrobacterium tumefaciens strains carry two T regions, TA and TB, with a complex oncogene arrangement. Within the octopine/cucumopine group, two main strain types were identified: large TA strains with a TA region resembling the TL region of the biotype I octopine strain Ach5 and small TA strains with a similar T region organization as the large TA strains but with a large internal TA deletion. Structural and functional studies of the representative large TA strain Tm4 revealed six oncogenes. Each oncogene was inserted in a disarmed vector and tested for biological activity using the corresponding oncogenes of Ach5 as standards. Five Tm4 oncogenes, TA-iaaM, T-ipt, T-6b, TB-iaaH and TB-iaaM, were shown to be active, the IS-interrupted TA-iaaH gene was inactive. To study the role of each gene in the pTiTm4 context, several single and multiple pTiTm4 mutations were constructed. It was shown that whereas TA-iaaM and TB-iaaH are essential for tumour formation on grapevine, T-ipt, T-6b and TB-iaaM are not. The avirulence of the TA-iaaM ^- mutant was shown to be due to an inhibitory effect of the T-ipt gene, since a TA-iaaM ^- /T-ipt ^- double mutant was fully virulent. We conclude that the TA-iaaM gene of large TA strains is specifically required to counteract the tumour growth inhibiting activity of the T-ipt gene. Both TA-iaaM and T-ipt are absent from the small TA strains. A model on the roles and interactions of the different oncogenes in large TA and small TA strains is presented.     

控制常绿针叶树叶量对树干生长的促进作用

一、前言近几年,在研究不同树种的修枝过程中,偶然发现,一些常绿针叶树的人工去叶能加快树干材积的生长,这引起了人们新的研究兴趣:控制常绿针叶树的叶量是否能促进树木生长?这一措施有多少可能的前途或弊端?多年来,人类为寻求促进林木生长的有效经营措施,利用各种手段进行了大量实验研究工作,获得了很有意义的成果,抚育间伐是其中的一项重要途径。由于世界各国的日益重视,60年代以来,很多学     

Genotypic variation in zinc efficiency and resistance to crown rot disease (Fusarium graminearum Schw. Group 1) in wheat

A crown rot disease in wheat caused by the fungusFusarium graminearum Schw. Group 1 is a widespread problem in chronically Zn-deficient Australian soils. A link between crown rot and Zn deficiency was established by Sparrow and Graham (1988). This paper reports a test of a further hypothesis, that wheat genotypes more efficient at extracting zinc from low-zinc soils are more resistant to infection by this pathogen. Three wheat cultivars (Excalibur, Songlen and Durati) of differential Zn efficiency were tested at three zinc levels (0.05, 0.5 and 2.0 mg Zn kg⁻¹ of soil) and three levels ofF. graminearum S. Group 1 inoculum (0.1 g and 0.3 g kg⁻¹ live chaff-inoculum and control having 0.1 g kg⁻¹ dead chaff inoculum). Six weeks after sowing dry matter production of shoots and roots was decreased byFusarium inoculation at 0.05 mg and 0.5 mg kg⁻¹ applied Zn.Fusarium inoculum at 0.1 g was as effective as 0.3 g kg⁻¹ for infection and decreasing dry matter. The infection at the basal part of culm decreased significantly by increasing the rate of Zn application. Excalibur, a Zn-efficient cultivar (tolerant to Zn deficiency) produced significantly more shoot and root dry matter, and showed less disease infection compared with Zn-inefficient cultivars (Durati and Songlen) at low (0.05 mg Zn kg⁻¹ soil) and medium (0.5 mg Zn kg⁻¹ soil) Zn fertilization rates. Higher rate of Zn fertilization (2.0 mg Zn kg⁻¹ soil) reduced the disease level in Durati to the level of Excalibur but the disease level of Songlen was still high, indicating its high Zn requirement and or sensitivity to crown rot. The data on Zn uptake show that Excalibur, being Zn-efficient, was able to scavenge enough Zn from Zn-deficient soil, we suggest that besides sustaining growth Excalibur was able to build and maintain resistance to the pathogen; inefficient cultivars needed extra Zn fertilization to achieve performance comparable to that of Excalibur. The present study indicates that growing Zn-efficient cultivars of wheat along with judicious use of Zn fertilizer in Zn-deficient areas where crown rot is a problem may sustain wheat production by reducing the severity of the disease as well as by increasing the plant vigour through improved Zn nutrition. ei]Section editor: R Rodriques-Kalana     

The relationship between colonisation and crown rot symptoms in strawberry plants infected with Phytophthora cactorum

Strawberry tissues infected with Phytophthora cactorum were comminuted and plated in a selective antibiotic agar medium to determine levels of tissue colonisation as indicated by the number of colony forming units (CFU) recovered per gramme of infected tissue. The number of CFU recovered per gramme of tissue increased logarithmically with the amount of necrosis in infected crown, leaf and petiole tissues. Under the conditions of enhanced susceptibility to infection and colonisation caused by cold storage treatments, this relationship between colonisation and necrosis was not significantly altered in the susceptible cv. Tamella. A recovery index was used to determine the effect of infected tissues on the recovery of CFU. This indicated that increasing levels of host colonisation stimulated CFU recovery and may partly explain the large increase in CFU g^-1 with larger amounts of necrosis. The amount of tissue colonisation was greater in inoculated plants of the susceptible cv. Tamella than in less susceptible cv. Cambridge Favourite, although the necrotic tissues of the latter contained more CFU g^-1, indicating a greater level of tolerance to colonisation. In cv. Tamella small amounts of colonisation were capable of causing wilt symptoms, although no wilted plants contained less than 200 CFU g^-1. Conversely, plants containing more than 1000 CFU g^-1 always wilted. In the early stages of infection, low levels of colonisation could be detected in strawberry crowns in the absence of symptoms. Dormant strawberry plants of cv. Tamella were readily infected by P. cactorum zoospore inoculations but, unlike actively growing plants, the majority of infections remained latent. These latent infections exhibited little or no symptoms and CFU recoveries from infected tissues were always below 100 CFU g^-1.