Molecular genetic features of polyploidization and aneuploidization reveal unique patterns for genome duplication in diploid Malus

Polyploidization results in genome duplication and is an important step in evolution and speciation. The Malus genome confirmed that this genus was derived through auto-polyploidization, yet the genetic and meiotic mechanisms for polyploidization, particularly for aneuploidization, are unclear in this genus or other woody perennials. In fact the contribution of aneuploidization remains poorly understood throughout Plantae. We add to this knowledge by characterization of eupolyploidization and aneuploidization in 27,542 F₁ seedlings from seven diploid Malus populations using cytology and microsatellite markers. We provide the first evidence that aneuploidy exceeds eupolyploidy in the diploid crosses, suggesting aneuploidization is a leading cause of genome duplication. Gametes from diploid Malus had a unique combinational pattern; ova preserved euploidy exclusively, while spermatozoa presented both euploidy and aneuploidy. All non-reduced gametes were genetically heterozygous, indicating first-division restitution was the exclusive mode for Malus eupolyploidization and aneuploidization. Chromosome segregation pattern among aneuploids was non-uniform, however, certain chromosomes were associated for aneuploidization. This study is the first to provide molecular evidence for the contribution of heterozygous non-reduced gametes to fitness in polyploids and aneuploids. Aneuploidization can increase, while eupolyploidization may decrease genetic diversity in their newly established populations. Auto-triploidization is important for speciation in the extant Malus. The features of Malus polyploidization confer genetic stability and diversity, and present heterozygosity, heterosis and adaptability for evolutionary selection. A protocol using co-dominant markers was proposed for accelerating apple triploid breeding program. A path was postulated for evolution of numerically odd basic chromosomes. The model for Malus derivation was considerably revised. Impacts of aneuploidization on speciation and evolution, and potential applications of aneuploids and polyploids in breeding and genetics for other species were evaluated in depth. This study greatly improves our understanding of evolution, speciation, and adaptation of the Malus genus, and provides strategies to exploit polyploidization in other species.     

Evolution of permease diversity and energy-coupling mechanisms with special reference to the bacterial phosphotransferase system

Different classes of apparently unrelated permeases couple different forms of energy to solute transport. While the energy coupling mechanisms utilized by the different permease classes are clearly distinct, it is proposed, based on structural comparisons, that many of these permeases possess transmembrane, hydrophobic domains which are evolutionarily related. Carriers may have arisen from transmembrane pore-forming proteins, and the protein constituents or domains which are specifically responsible for energy coupling may have had distinct origins. Thus, complex permeases may possess mosaic structures. This suggestion is substantiated by recent findings regarding the evolutionary origins of the bacterial phosphoenolpyruvate-dependent phosphotransferase system (PTS). Mechanistic implications of this proposal are presented.     

Nuclear bodies in human prostate with special reference to appearance rate

The Nuclear Body Appearance Rate in seventeen human prostatic cases was statistically analyzed according to three lesion areas--the hyperplastic nodule, non-nodule and atrophic--in the secretory epithelium and basal cells. It was meaningfully high in the secretory epithelium of the hyperplastic nodule, but not in the other two lesion areas. There was no meaningful result in basal cells. Though there is a wide variety of reported data on the human prostate, particular care must be taken in analysis at the electron microscopic level, keeping in mind that even in a single specimen this organ has a notable variety of tissue changes. The Nuclear Body Appearance Rate reflects cellular hyperactivity although it does not have a specific known function at present.     

Aberrant chromosomal sex-determining mechanisms in mammals, with special reference to species with XY females

Both mouse and man have the common XX/XY sex chromosome mechanism. The X chromosome is of original size (5-6% of female haploid set) and the Y is one of the smallest chromosomes of the complement. But there are species, belonging to a variety of orders, with composite sex chromosomes and multiple sex chromosome systems: XX/XY1Y2 and X1X1X2X2/X1X2Y. The original X or the Y, respectively, have been translocated on to an autosome. The sex chromosomes of these species segregate regularly at meiosis; two kinds of sperm and one kind of egg are produced and the sex ratio is the normal 1:1. Individuals with deviating sex chromosome constitutions (XXY, XYY, XO or XXX) have been found in at least 16 mammalian species other than man. The phenotypic manifestations of these deviating constitutions are briefly discussed. In the dog, pig, goat and mouse exceptional XX males and in the horse XY females attract attention. Certain rodents have complicated mechanisms for sex determination: Ellobius lutescens and Tokudaia osimensis have XO males and females. Both sexes of Microtus oregoni are gonosomic mosaics (male OY/XY, female XX/XO). The wood lemming, Myopus schisticolor, the collared lemming, Dirostonyx torquatus, and perhaps also one or two species of the genus Akodon have XX and XY females and XY males. The XX, X*X and X*Y females of Myopus and Dicrostonyx are discussed in some detail. The wood lemming has proved to be a favourable natural model for studies in sex determination, because a large variety of sex chromosome aneuploids are born relatively frequently. The dosage model for sex determination is not supported by the wood lemming data. For male development, genes on both the X and the Y chromosomes are necessary.     

Chromosome anomalies in 2 cases of human ovarian cancer

Cytogenetic analysis of two human ovarian adenocarcinomas show identical specific anomalies. These two tumors exhibit, in all the analysed mitosis, a paracentric inversion of chromosome 3 and a translocation between chromosomes 2 and 5. A relationship between these markers and the location of human oncogenes on chromosomes 2, 3 and 5 should be considered.     

Immunohistochemistry of chondromodulin-I in the human intervertebral discs with special reference to the degenerative changes

The expression of the matrix protein chondromodulin-I has been studied in human intervertebral discs of 101 people using immunohistochemical analyses. The purpose of this report is to present data on the metabolic changes that were found to occur in the chondrocytes of intervertebral discs during development and aging. Chondromodulin-I was highly expressed during the gestational period and gradually decreased after maturation. It was detected in both the extracellular matrix and chondrocytes in the zone of hypertrophic cartilage, the zone of proliferative cartilage and the zone of resting cartilage in fetal discs. It was also present in the annulus fibrosus, nucleus pulposus and end-plate cartilage in mature discs. In degenerative discs, chondromodulin-I immunoreactivity tended to be elevated in the remaining chondrocytes. Our findings suggest that the expression of the protein is developmentally regulated and upregulated through a defense mechanism against the degenerative processes of the aged intervertebral disc.     

Protein-secretory patterns of normal and abnormal human placentas with special reference to human chorionic gonadotropin

[35S]Methionine-labeled protein-secretory patterns resolved by two-dimensional polyacrylamide gel electrophoresis in abnormal hydatidiform-mole placentas were compared with those in normal full-term placentas with special reference to human chorionic gonadotropin (hCG) by means of immunoblotting and immunoelectron-microscopic techniques. Although basic protein-secretory patterns of both placentas were similar to each other, four polypeptide spots appeared and one spot disappeared in the hydatidiform-mole samples. Among four newly synthesized and secreted spots, three were immunoreacted with anti-hCG serum by an immunoblotting experiment. Ultrastructural localization of hCG showed that the labeling intensity of anti-hCG serum in hydatidiform-mole placentas was much heavier than that in full-terms ones. Particularly, the Golgi apparatus, middle-sized granules and large bodies were highly immunoreactive. The present study reveals that hydatidiform-mole placentas have different protein-secretory functions especially in hCG synthesis and secretion from those of normal pregnancy.