Studies on triploid Allium triquetrum

This work describes the relationship between the univalents seen at metaphase I and the distribution of dyads at anaphase I in the pollen mother cells of triploid Allium triquetrum. The orientation of the centromeres within the trivalents and bivalents at metaphase I towards the two poles of the pollen mother cells is random. The distribution of polar univalents towards the two poles at metaphase I is also random, as is the distribution of dyads at anaphase I in low univalent frequency collections. However, in a high univalent frequency collection, the distribution of dyads at anaphase I is non-random. There is an excess of cells with the most equal dyad distribution (13–14) and a paucity of cells with a 12–15 distribution. In low univalent frequency collections, the equatorial univalents are believed to remain in the equatorial region during anaphase I and are seen as laggards at late anaphase I. The remaining chromosomes move according to the metaphase I orientation of their centromeres to give a random distribution of dyads at anaphase I. In high univalent frequency collections it is argued that the non-random dyad distribution seen at anaphase I is the result of non-random movement of some of the equatorial univalents away from the equatorial region during anaphase I. The remaining equatorial univalents remain in the equatorial region and are seen as laggards at late anaphase I.     

Structural aspects and ecophysiology of anther opening in Allium triquetrum

BACKGROUND AND AIMS: Tissue desiccation is considered to be involved in anther opening, and it is agreed that environmental humidity affects its timing. Different sources of evidence suggest that the later steps of the process (i.e. stomium opening and outward wall bending) are regulated in different ways. Anther opening was studied in Allium triquetrum under four regimes of relative humidity (RH) to analyse the effect of this parameter and to speculate about its possible regulation. METHODS: Anther histology was studied in cross-sections under a microscope. The times of visible anther opening and complete outward wall bending were recorded separately for each level of RH. Frequency distributions were plotted to express anther behaviour. KEY RESULTS: When a longitudinal stomium breaks the anther remains closed due to adherence of walls on each side of the stomium. Anther opening occurs when the adhering walls subsequently separate. Later, the walls shrink laterally and bend outward. The anthers of the inner whorl opened during the morning of the first day of anthesis, while those of the outer whorl opened during the afternoon. Low RH (20 %) did not cause any evident acceleration of anther opening, but it did cause delay and inhibition of the opening of some anthers in the outer whorl. High RH (55 and 98 %) caused different degrees of delay and also inhibition of anther opening, but most anthers opened within the expected range of time. The time taken for outward wall bending was shortened at 20 % RH. Anther wall outward bending was inhibited at 55 % and 98 % RH. CONCLUSIONS: Anther opening occurred at a specific moment of anther development, separated in time from stomium breakage, and seemed related to dehydration caused by reabsorption of water by contiguous tissues. Outward bending of the wall was facilitated by evaporation. Anther opening and anther wall outward bending seemed to be regulated differently in relation to water control.     

Studies on the Constituents of Desmodium triquetrum (L.)DC

Three crystalline compounds have been isolated from the Desmodium triquetrum (L.) DC. On the basis of their spectroscopic data and chemical correlations, the structures have been identified as friedelin (Ⅰ), epi-friedelinol (Ⅱ), stigmasterol (Ⅲ). They were obtained for the first time from the Desmodium triquetrum (L.) DC.     

Prometaphase I and anaphase I in an interchange heterozygote of Allium triquetrum (Liliaceae)

Four unstable malorientations in a chain quadrivalent, as well as maloriented bivalents, were studied in fixed prometaphase I pollen-mothercells from an interchange heterozygote of Allium triquetrum. The relative frequencies of these malorientations, in cells from pollen sacs of different developmental ages, suggest that maloriented bivalents, on the average, reorient before maloriented quadrivalents; and that, similarly, there are differences in the timing of reorientation amongst the four types of maloriented quadrivalents. — Further, the proportion of anaphase I cells derived from alternate orientation in the interchange quadrivalent is lower than expected in pollen sacs with a high percentage of cells in mid-anaphase; but higher than expected in pollen sacs in which relatively few cells have as yet proceeded into anaphase, and also in those in which most cells have already passed through anaphase. Arguably, these data are a direct outcome of the differential behavior of unstable maloriented quadrivalents in the preceeding prometaphase.     

Studies on the mitotic chromosome scaffold of Allium sativum

An argentophilic structure is present in the metaphase chromosomes of garlic(Allium sativum),Cytochemical studies indicate that the main component of the structure is non-histone proteins(NHPs).The results of light and electron microscopic observations reveal that the chromosme NHP scaffold is a network which is composed of fibres and granules and distributed throughout the chromosomes.In the NHP network,there are many condensed regions that are connected by redlatively looser regions.The distribution of the condensed regions varies in individual chromosomes.In some of the chromosomes the condensed regions are lognitudinally situsted in the central part of a chromatid while in others these regions appear as coillike transverse bands.At early metaphase.scaffolds of the sister chromatids of a chromosome are linked to each other in the centromeric region,meanwhile,they are connected by scafold materials along the whole length of the chromosome.At late metaphase,however,the connective scaffold materials between the two sister chromatids disappear gradually and the chromatids begin to separate from one another at their ends.but the chromatids are linked together in the centromeric region until anaphase.This connection seems to be related to the special structure of the NHP scaffold formed in the centromeric region.The morphological features and dynamic changes of the chromosome scaffold are discussed.     

Studies on male and female meiosis in Indian Allium

Male meiosis in autotetraploid Allium tuberosum (4×=32) is fairly regular, keeping in view its cytological status, with 81 percent of the chromosomes associated in quadrivalents and trivalents. About 5% of the cells have 32 univalents. Anaphase segregation is slightly irregular. While 48% of the pollen mitoses show 16 chromosomes, 87% of the mature pollen is viable as indicated by carmine or iodine staining. — Megaspore mother cells have 64 chromosomes associated in 32 bivalents at metaphase I. Anaphase segregation is normal. In three out of 56 cells studied multivalents, bivalents and univalents are observed as in male meiosis. — It is concluded that the species reproduces by pseudogamous parthenogenesis made possible by meiotic modification. This modification is almost perfect and almost completely specific for female meiosis. Slight effects are observed in male meiosis.     

Studies on male and female meiosis in Indian Allium

Frequency and position of chiasmata at diplotene were studied in pollen mother cells and megaspore mother cells of the same plants of two wild Allium species (A. consanquineum and A. kachrooi) and two cultivated species (a. cepa and A. nigrum), all diploid with 2n=16. Contrary to most reports on sex differences in recombination, chiasma frequencies were higher in male than in female meiosis in all cases. Chiasmata were non-localised except in A. kachrooi megaspore mother cells where they were proximally localised.     

昆明地区滇韭形态及染色体多态性研究

对昆明地区滇韭的 8个当地居群开展了形态及核型研究 ,并对形态及染色体性状进行了巢式方差分析。结果表明 :滇韭的形态性状在居群内具丰富多态性 ,在居群间具明显多型性 ;核型较对称 ,存在两种倍性的分化 :梁王山居群为二倍体 (2x) ,昆明居群为四倍体(4x)。二倍体核型公式为K (2n ) =2x =16 =14m 2sm ,四倍体核型公式为K (2n ) =4x =32=2 8m 4sm。滇韭的染色体因存在倍性变化、B -染色体形态和数目变化及随体染色体的形态和大小变化而具有一定程度的多态性。     

Studies on the Karyotype of 5 Samples of Allium Sect. Bromatorrhiza Ekberg

The karyotypes of 5 samples in Allium Sect. Bromatorrhiza Ekberg were analysed in this paper. In Allium wallichii Kunth, the first sample is a diploid, with genome formula is AA and karyotype formula is K(2n)=2x=14=2m(SAT)+2m+10sm. The second is an autotetraploid, with genome formula AAAA, karyotype formul K(2n)=4x=28=2m(SAT)+6m+20sm. These two karyotypes belong to “3A”. The two karyotypes of A. wallichii Kunth are similar in morphology, though different in ploidy. In Allium hookeri Thwaites, the first sample is a dibasic autoallotriploid. Its genome formula is AAB₁; the basic number of the genome A is 7 and that of the genome B₁ is 8. The karyotype formula is K(2n)=2x+x'=22=(12sm+2t)+(1m+4sm+1st+2t). The second is also an autoallotriploid. The genomes in pairs are similar to those in the first sample in size and morphology of chromosomes. However, the unpaired genome differs from the first one apparently. Therefore, its genome formula is AAB₂, and karyotype formula is K(2n)=2x+ x'=22=(12sm+2t)+(3m+1sm+2st+2t). The third is doubling of the first karyotype. It is an autoallohexaploid, with genome formula AAAAB₁ B₁ and karyotype formula K(2n)=4x+2x'= 44= (24sm+4t) + (2m+8sm+2st+4t). These three karyotypes belong to “3A”.     

Studies on the anticandidal mode of action of Allium sativum (garlic)

The mode of action of aqueous garlic extract (AGE) was studied in Candida albicans. The minimum inhibitory concentration (MIC) of AGE against six clinical yeast isolates ranged between 0.8 and 1.6 mg ml-1. Scanning electron microscopy and cell leakage studies showed that garlic treatment affected the structure and integrity of the outer surface of the yeast cells. Growth of C. albicans in the presence of AGE affected the yeast lipid in a number of ways: the total lipid content was decreased; garlic-grown yeasts had a higher level of phosphatidylserines and a lower level of phosphatidylcholines; in addition to free sterols and sterol esters, C. albicans accumulated esterified steryl glycosides; the concentration of palmitic acid (16:0) and oleic acid (18:1) increased and that of linoleic acid (18:2) and linolenic acid (18:3) decreased. Oxygen consumption of AGE-treated C. albicans was also reduced. The anticandidal activity of AGE was antagonized by thiols such as L-cysteine, glutathione and 2-mercaptoethanol. Interaction studies between AGE and thiols included growth antagonism, enzymic inhibition and interference of two linear zones of inhibition. All three approaches suggest that AGE exerts its effect by the oxidation of thiol groups present in the essential proteins, causing inactivation of enzymes and subsequent microbial growth inhibition.     

Diploid and triploid offspring of triploid agamosporous fernDryopteris pacifica

A cytological and reproductive study of the diploid and triploid agamosporousDryopteris pacifica was made to elucidate the origin of its infraspecific cytotypes. Some triploids produced 16 spore mother cells (SMCs) sometimes with n=41II+41I chromosomes, in addition to eight SMCs with n=123II, in each sporangium. In the former case the 16 SMCs usually underwent abnormal meiosis to give rise to some 50 spores, some of which were regular-shaped; in the latter the eight SMCs multiplied into 32 spores by normal meiosis. We found that spores from one of the triploid plants developed into either diploid or triploid gametophytes, which further apogamously produced diploid or triploid sporophytes, respectively. This novel mechanism of ploidy reduction is discussed in relation to the origin of diploid agamosporous ferns, the taxonomic complexity of the species, and the correlation of agamospory with polyploidy. The mechanism is also compared to that operating in agamospermous angiosperms.     

大葱组织培养中玻璃苗特性研究

以章丘大葱为试验材料,从形态组织学及生理生化等方面探讨了大葱试管苗玻璃化发生的可能机理。结果表明,玻璃苗形态组织结构与正常苗有很大差异,玻璃苗组织含水量增加,过氧化物酶(POD)活性增强,叶绿素总量、叶绿素a、叶绿素b、过氧化氢酶(CAT)的活性、可溶性蛋白含量均降低。玻璃苗酯酶同工酶谱带与正常苗相比,增加了一条带,同时缺少了两条带;可溶性蛋白电泳分析表明,玻璃苗与正常苗间也存在明显差异。可见,当外界环境条件不适宜植物生长需要时,植物体在基因表达水平上将会受到影响,表达产物的差异可引起生理代谢功能上的紊乱,从而导致形态结构的畸型,进而产生玻璃化苗。     

Human triploid embryo

Summary A cytogenetic and anatomopathologic study of an embryo of 24 mm crown-rump length showing pure triploidy (69,XXY) is reported. Anomalies such as unilateral genitourinary agenesia, aortic alterations, defects in cerebral development, and anomalies of the chorionic villi were detected.     

韭不同倍性及其非整倍体的ITS序列变异研究

对不同倍性及其非整倍体韭Allium tuberosum和野韭Allium ramosum核糖体DNA的内部转录区(ITS)进行了PCR扩增和克隆,并测定10个ITS1和ITS2的序列,用ITS1 ITS2的序列探讨Allium tuberosum和Allium ramosum的系统发育关系。研究表明,Allium tuberosum与Alli-um ramosum种间的平均Kimura遗传距离仅为0．0146,二者是一对近缘种。虽然韭经历了长期的人工选择和自然选择,但与野韭的分化仍然较小。韭不同倍性及其非整倍体之间,其ITS序列亦无明显差异。     

Studies on the uptake of trivalent and hexavelent chromium by onion (Allium cepa)

Abstract

Experiments were conducted to examine the uptake and translocation of root-absorbed trivalent and hexavalent state of chromium in the onion plant (Allium cepa) grown in soil and sand culture. Chromium content in plant tissues increased with increasing amount of added chromium. Distribution of chromium in the plant in general, found to be in the order: root>>bulb>shoot. Higher uptake in the plants grown in sand from both the sources of chromium was observed as compared with the corresponding values for soil culture. Morphological and growth effects of the treatments of different oxidation state of chromium indicated that higher doses of Cr(VI) [150 and 300 μg mL^?1] were more toxic to the onion plants compared to equivalent doses of Cr(III).     

Studies of Chromosome Banding with Giemsa in Vicia faba and Allium cepa

Giemsa dye is a complex mixture containing methylene blue, its oxidation products-azure Ⅰ, Ⅱ, Ⅲ, and their eosinate. The results of our experiments have demonstrated that staining with methylene blue alone can give a faint trace of banding as well as azure Ⅰ, Ⅱ. No bands are obtained with eosin. Nevertheless, good chromosome bandings can be often produced by staining with methylene blue-eosinate or azure Ⅱ-eosinate. These data indicate that eosinate has an important effect for the formation of C-banding on plant chromosomes. In our experiments, the treatments of chromosomes with trypsin or papain have also resulted in good C-banding pattern when slides are stained with Giemsa. We found that the slides untreated with proteinase showed homogeneous intense chromosome staining and, on the contrary, the slides treated with proteinase led to palestaining chromosomes and presenting bandings. It has shown that proteinase, especially trypsin, not only can remove a large amount of chromosomal protein but also can remove DNA and results in C-bandings. Treated properly with trypsin and followed by the Feulgen staining, chromosomes can also produce the C-bandings, but chromosomes treated overtime with trypsin are stained more palely in Feulgen reaction or lead to colourlessness. The above results have further proved that trypsin technique removes large amounts of chromosome DNA and removes less from the C-band regions than from the non-band regions. In this paper we mainly discussed the effects of protein on mechanism of plant chromosome banding. We consider that the production of plant C-banding is probably due to the differential accessibility of nucleoprotein between euehromatin and heteroehromatin regions. It brings about selective removal of nucleoprotein from the chromosome arms. We have compared the effect of trypsin with papain and pepsin on producing bands. Good bands are produced by Giemsa staining chromosomes with trypsin, but no bands are obtained by staining chromosomes treated with pepsin. So the results have expressed that histones are possibly playing more important role in C-bandings.