摘要:

The presence of subunits in chloroplast membranes is suggested by polarization, fluorescence, and X‐ray studies. Subunits (quantasomes) may be observed in the electron microscope on dried shadowed membranes and in replicas of membranes produced by the freeze‐etching technique. Regular subunits are also observed with the electron microscope in thin sections of chloroplast membranes. Chemical considerations suggest that many membranes are composed of lipoprotein subunits. Thin sections reveal two types of chloroplast membranes, the fret membranes composed of one layer of subunits, and the partitions composed of two layers of subunits. Chloroplast membranes consist of about 45% protein and 55% lipid. Some 80% of the lipids are the highly surfactant glycolipids. In this paper the subunits are visualized as assymetric lipoproteins, probably having a protein core surrounded by components determined by the nature and environment of the membrane. Since the stroma, fret channels, and loculi contain aqueous materials, it is further postulated that the membranes bordering these spaces bind the highly surfactant glycolipids. The region between the two rows of subunits in the partition appears to be highly hydrophobic, rich in chlorophyll, and low in glycolipids. Some chlorophyll also may occur within the subunits both in the partitions and in the fret membranes. Since four subunits appear to comprise a quantasome, at least two types of forces, inter‐ and intra‐quantasome forces, bind the subunits together in sheets. Chloroplast membranes thus differ from a “unit membrane” in two important respects: (1) they must be an aggregate of globular subunits, and (2) the lipoprotein subunits consist of a protein matrix which binds the chlorophylls and lipids by hydrophobic association with their hydrocarbon moieties.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10656.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Emasculated and unemasculated crosses of tetraploidA. spicatumf.inermeXA. desertorumyielded four hybrids. The hybrids were morphologically intermediate between the parent species but resembledA. desertorummore closely thanA. spicatum.Both parents behaved cytologically as autoploids. Mean chromosome associations of 0.04 I, 8.60 II, 0.01 III, and 2.67 IV were observed at diakinesis in the 28‐chromosomeA. spicatum.TheA. desertorumparent contained 30 chromosomes, 2 of which were likely supernumeraries, and averaged 0.03 I, 9.85 II, and 2.57 IV at diakinesis. Three hybrids contained 30 chromosomes, and one had 29. The most common chromosome association in the 30‐chromosome hybrids was 2 I and 14 II; and the average was 3.00 I, 13.40 II, 0.06 III, and 0.01 IV.A. spicatumandA. desertorumchromosomes were usually distinguishable from each other in the hybrid cell on the basis of size. All pairing in the hybrids was attributed to autosyndesis within parental genomes.A. spicatum, A. desertorum, and their hybrids were represented by genome formulas of SSSS, CCCC, and SSCC, respectively. The hybrids produced 5 to 439 seeds under open pollination. Three controlled crosses between the hybrids yielded 2, 5, and 23 seeds, respectively, on 10 maternal spikes in each cross. The prospects of developing a fertile, cytologically stable allotetraploid species from the hybrids appear favorable.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10657.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Both kinetin and adenine promote bud initiation in excised cotyledons ofLactuca sativa.Controls lacking these substances form abundant roots but have never formed buds. Indoleacetic acid and certain mineral salts are also necessary for regeneration of shoots. Although bud growth from cotyledons is extensive on a medium containing both indoleacetic acid and kinetin, excised roots display a low propensity toward bud formation and typically develop callus tissue with roots. Growth of hypocotyl sections is intermediate with respect to bud formation. Shoot initiation in lettuce thus varies with the region of the seedling as well as with the culture medium.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10658.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Developmental changes in the vascular cambium ofLeitneria floridana, a shrub, were determined primarily by an analysis of the secondary xylem. During the production of the first growth ring of secondary xylem, 37% of the anticlinal divisions in the fusiform initials were lateral, the remaining were oblique. The oblique partition averaged ½ of the length of the dividing initials during this period of growth. Following their origin in anticlinal division, daughter cells elongated at a rapid rate until they were about as long as the mean for all cells, and then most cells elongated at a slow rate. Almost all initials survived during the formation of the inner secondary xylem (growth rings 1–10), and few new rays were formed from fusiform initials. During the production of the outer secondary xylem (growth rings 22–26), lateral divisions accounted for less than 5% of all anticlinal divisions. The oblique partition averaged only ¼ of the length of the dividing cells during this period, although the mean length of dividing initials was relatively constant throughout secondary growth. About 20% of the initials studied during the deposition of the outer secondary xylem disappeared from the cambium, and many others were transformed into ray initials. The findings are discussed in relation to the developmental changes in the vascular cambium in plants of different habits.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10659.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Quantitative methods, with round‐the‐clock collecting of large samples in successive years, have uncovered several new phenomena of sieve‐tube differentiation in young leaves ofColeusvegetative shoots. In small leaves (1–350μ), there are no sieve tubes in the leaf itself, but they differentiate acropetally in the two traces to each leaf. Regression lines fitted to the data for leaf length vs. most distal position of sieve tubes in the traces support the view that differentiation is steady and acropetal, but they also reveal that differentiation in the traces falls steadily farther behind elongation of the leaf. Leaves more than 500μlong have sieve tubes close to their tips. An intensive search of leaves of intermediate lengths revealed an isolated locus of sieve‐tube differentiation. These relationships were reproducible year after year. Every plant with discontinuous strands of sieve tubes in the second leaf pair had discontinuous xylem in the third. This isolated locus was not seen before, probably because of small samples and daytime collections; most of our cases were from night collections.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10660.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

The unique leaf structure of the genusAnemiawith its upright fertile basal pinnae has been interpreted as derived from the typical fern leaf with unmodified basal pinnae. Reported herein for the first time is the leaf morphology of a species,Anemia colimensisMickel, which shows the most primitive condition known in the genus and clearly confirms the course of evolution. The fertile pinnae are but little modified in size, lamination, and posture. AlthoughA. colimensishas characters of two subgenera, it is shown to be a primitive element in subgen.Anemiorrhizaand not a member of subgen.Coptophyllumas previously reported.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10661.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

InSchizophyllum communeandCoprinus lagopusthe frequency of hyaline hyphal tips adjacent to anastomoses reflects the degree of incompatibility between mated strains. The lowest percentage is associated with full compatibility, the highest with full incompatibility. The hyaline hyphal tips appear several hours after an anastomosis has been detected. The data suggest that the factor(s) responsible for a cytoplasmic incompatibility is not constitutive but is induced at the time of mating.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10662.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

A single gene, recessive mutation ofSchizophyllum commune, designated asthin, is characterized by its sparse growth on agar and unusual hyphal morphology. Many hyphae exhibit various degrees of “waviness,” although some branches of these wavy hyphae appear normal. Differences in cell size and branch development between normal andthinstrains are also noted. Most of the characteristics attributed tothinvary quantitatively between strains. In addition, considerable variability in hyphal characteristics can be found in a single strain.Thinmutants behave as bilateral maters. In matings where the normal allele is present, genetic complementation occurs and normal clamped cells are produced. Fruit bodies with viable spores are formed on both thethinand normal sides of the mating.ThinXthinmatings give a stable dikaryon, but they retain thethinmorphology and do not produce fruit bodies. Evidence that there is only one locus for thethinmutation is presented. Certain aspects of the variability ofthins, the possible role of extracellular polysaccharide, and the potential uses forthinstrains in studies of hyphal and fruit body development are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10663.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Vapor‐phase chromatographic patterns obtained from the distilled essential oils of 20 taxa in the genusMonarda(Labiatae) are discussed. The influence of leaf tissue maturity, plant habitat, and oil storage upon the composition of the essential oils was investigated, as well as similarities of leaf and flower oils in the same plant. The taxa of the subgenusCheilyctishave very similar chromatographic “fingerprints” which confirm their homogeneity. On the other hand, the polyploid subgenusMonardahas heterogeneous patterns of essential oil composition among its species. A population ofM. fistulosagave evidence of being a chemical race.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10664.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Diameter and wall thickness of tracheids and the fibrillar angle in their S2layers were investigated at five relative heights within two increment sheaths of one dominant loblolly pine (Pinus taedaL.). The sheaths investigated were formed during extremes of soil moisture availability. In both increment sheaths the radial and longitudinal trends of the respective anatomical features were similar; however, the sheaths differed in the degree and rate at which their size changed from the apex to the base of the tree. Soil moisture conditions directly affected the width of the annual rings, tracheid diameter, and wall thickness but not the fibril angle of tracheid walls.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10665.x

出版商:Wiley    

年代:1967

数据来源: WILEY