منابع مشابه
Sex chromosomes in land plants.
Sex chromosomes in land plants can evolve as a consequence of close linkage between the two sex determination genes with complementary dominance required to establish stable dioecious populations, and they are found in at least 48 species across 20 families. The sex chromosomes in hepatics, mosses, and gymnosperms are morphologically heteromorphic. In angiosperms, heteromorphic sex chromosomes ...
متن کاملSex chromosomes in flowering plants.
Sex chromosomes in dioecious and polygamous plants evolved as a mechanism for ensuring outcrossing to increase genetic variation in the offspring. Sex specificity has evolved in 75% of plant families by male sterile or female sterile mutations, but well-defined heteromorphic sex chromosomes are known in only four plant families. A pivotal event in sex chromosome evolution, suppression of recomb...
متن کاملHigher Plants
Contamination with 2,4,6-trinitrotoluene (TNT) is widespread at sites of past munitions manufacture. It is moderately toxic to plants and highly toxic to some animals. Some aquatic plant species have been observed to promote degradation of TNT. The degradative activity is associated with the root systems but products are found in the surrounding medium. We have examined a range of sixteen gener...
متن کاملHigher-order structure of human mitotic chromosomes.
From observations on the partial disintegration of isolated human metaphase chromosomes we propose that human metaphase chromatids have a rather simple organization based on the folding and coiling of a long, regular, hollow cylindrical structure with a diameter of about 4000 A. This cylindrical structure, the unit fiber, is postulated to be a super-solenoid formed by the coiling of a 300 A sol...
متن کاملNanoparticles and higher plants
Nanomaterials and nanotechnology have been widely applied in the world in this last decade. Nanotechnology provides the tool and the technological platforms for the study and transformation of biological systems. Few studies have focused on the effects and mechanisms of nanomaterials on plants. The results of these studies have been reported with the aim to provide further insight into connecti...
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ژورنال
عنوان ژورنال: Nature
سال: 1956
ISSN: 0028-0836,1476-4687
DOI: 10.1038/178007b0