THE CYTOLOGY AND PHYLOGENETICS OF THE DIPLOID SPECIES OF GOSSYPIUM

Meiotic chromosome behavior of 11 inter-genomic hybrids of Gossypium (2n = 26) were investigated. Per cell univalent frequencies at meiotic metaphase I in these hybrids were: A genome × Cgenome—G. herbaceum × sturtianum, 10.53; G. herbaceum × australe, 18.05. A genome × E genome—G. smnalense × arboreum, 21.82. B genome × C genome—G. anomalum × sturtianum, 9.23; G. anomalum × australe, 13.11. B genome × D genome—G. anomalum × klotzschianum, 17.45; G. anomalum × raimondii, 18.83. C genome × D genome—G. robinsonii × davidsonii, 12.77; G. sturtianum (armourianum × thurberi), 8.63. C genome × E genome—G. somalense × australe, 23.78; G. somalense × bickii, 25.58. Trivalent and quadrivalent frequencies were relatively high for those hybrids involving a C genome species, indicating that a reciprocal translocation differentiates the C genome from the A, B, D, and E genomes. The results of this study and the data of similar studies cited from the literature on Gossypium cytogenetics are discussed relative to the phylogenetics and evolution of the major (genome) groups of Gossypium and their constituent taxa.     

The effects of different steroids on costal and epiphyseal cartilage of fetal and adult rats

Summary The effects of different doses of various steroids on growth, and on costal and epiphyseal chondrocytes, have been studied in prenatal, immature, and adult Long-Evans rats using histochemical techniques, and both light and electron microscopy. Both prenatal and postnatal treatments have been employed. The steroids used were cortisone (CA), betamethasome (BM), and, in the prenatal group only, dexamethasone (DM).Body weight is reduced in all treated rats (except the low dose of CA) by day 17 of gestation, with greater weight reductions occurring in rats receiving the higher dose level of each steroid. In rats treated prenatally or neonatally, and sacrificed postnatally on days 39–43 or days 116–127, body weights, and tibial and tail lengths, are less than in correspondingly aged controls, thus showing a persistence of the effects of treatment.Costal and epiphyseal cartilages in prenatal rats show cellular, synthetic, and ultrastructural alterations induced by treatment with glucocorticoids but the responses are not necessarily comparable. Except for the low dose of DM, the higher doses of each steroid are more effective in inhibiting, or altering, growth and cellular differentiation in the developing fetuses. Surprisingly, a low dose of DM has a more devastating effect on the cells and extracellular matrix of both costal and epiphyseal cartilage, than do higher dose-levels of the various steroids. Low doses of CA and BM are also effective in inhibiting or altering growth and cellular differentiation, but their effectiveness is largely limited to 17 days of gestation. The order of effect of the various doses of the different steroids on fetal cartilage, listed in decreasing order of severity, is as follows: 0.12 DM, 0.24 DM, 0.42 BM, 50 CA, with 25 CA and 0.18 BM being approximately equal and only slightly different from control cartilages. The effect of prenatal or neonatal glucocorticoid treatment on chondrocytes is minimal in the 30–43 day, or 116–127 day, postnatal groups. In immature and adult rats, cortisone affects the chondrocytes more deleteriously than does betamethasone, and a 5.0 mg dose of CA seems to affect chondrocytes, body weight, and tibial and tail lengths more than 0.2 or 7.5 mg doses.Supported in part by NIH grant HD 07074 and HD 12034     

The integrity of proteoliposomes adsorbed on a biosurface

Proteoliposomes encapsulating [¹⁴C]glucose have been prepared from a mixture of dipalmitoylphosphatidylcholine and phosphatidylinositol by sonication (SUV) and reverse phase evaporation (REV) and conjugated with wheat germ agglutinin (WGA). The proteoliposomes were characterised in terms of size and composition and covered a range of size (weight-average diameter) from approximately 60–330 nm and surface-bound WGA (weight-average number of protein molecules per liposome) from approximately 70 to 3000. Methods have been developed for assessing the extent of adsorption and integrity of the proteoliposomes when targeted to glycophorin A-coated microtitre wells. From the amount of [¹⁴C]glucose released by detergent disruption from the adsorbed proteoliposomes it is found that the extent of adsorption increases with proteoliposome size and WGA conjugation and that the integrity of the proteoliposomes remains intact on adsorption. The results can be explained in terms of monolayer coverage of the surface with preferential adsorption of larger proteoliposomes from the size distribution.     

The structure of the iron complex in metaquohemerythrin

The novel binuclear iron complex in metaquohemerythrin is described. One of the two iron atoms is octahedrally coordinated, the other being penta-coordinate. A number of questions concerning the structure of the metal complex in different forms of this nonheme iron oxygen transport protein have been clarified. The structure of the complex presented here differs from that of metazidohemerythrin in that the Fe atom providing the binding locus for azide ion is five-coordinate with no small molecule ligand bound to it. The coordination polyhedron of this Fe is best described as a trigonal bipyramid.