DISTRIBUTION OF ENZYMATIC BROWNING OF YOUNG SHOOT HOMOGENATES IN THE AURANTIOIDEAE

Distribution of polyphenol oxidase-catalyzed browning of young shoot homogenates was studied in 428 accessions of the orange subfamily Aurantioideae. Browning and nonbrowning phenotypes were found in both tribes, namely Clauseneae and Citreae. The browning taxa had sufficient polyphenol oxidase activity and a presently unknown phenolic substrate, while the nonbrowning taxa were devoid of both. A third group of taxa contained the substrate only and they too were designated as browning since their homogenates turned brown when the enzyme from a known source was added. The color of homogenates was taxon-specific in most browning and nonbrowning taxa. Within the genus Citrus, 4 out of the 16 species recognized by Swingle were browning and 2 were nonbrowning. Exceptions noted within either group of taxa were presumably hybrids or mutants. The significance of enzymatic browning as an additional taxonomic criterion in studying species relationships and as a genetic marker in identificaton of hybrid taxa was discussed.     

THE SUBCELLULAR DISTRIBUTION OF CARBONIC ANHYDRASE IN HOMOGENATES OF PERFUSED RAT BRAIN

Abstract— The distribution of carbonic anhydrase was examined in subcellular fractions of perfused rat brain and compared with those of markers for cytosol (lactic dehydrogenase), mitochondrial matrix (glutamic dehydrogenase), and mitochondrial membranes (succinic dehydrogenase). About half of the total carbonic anhydrase was found in particulate fractions, with the greatest part of this in the crude mitochondrial fraction. This fraction was separated into its components on a discontinuous sucrose gradient either as such or after isotonic mechanical disruption with a French pressure cell, and the resultant fractions were characterized by electron microscopy and by assay of marker enzymes.
Carbonic anhydrase was solubilized by mechanical disruption, but not to the same extent as lactic dehydrogenase. The highest specific activity for carbonic anhydrase was found in the myelin fraction of the gradient. A mitochondrial locus for carbonic anhydrase is unlikely, but the presence of the enzyme in synaptosomes remains in question.
Addition of soluble carbonic anhydrase did not significantly increase the activity of particulate fractions. Treatment of particulate fractions with detergent was necessary to reveal latent activity; this procedure resulted in a more than ten-fold increase in the measurable carbonic anhydrase activity of myelin fragments.     

COMPARATIVE MORPHOLOGY OF THE COCHLOSPERMACEAE. II. ANATOMY OF THE YOUNG VEGETATIVE SHOOT

The generic scope and systematic position of the Cochlospermaceae were evaluated using observations from the anatomy of the stem, node, and leaf. There are few basic differences in vegetative anatomy between Amoreuxia and Cochlospermum. Secretory cells and canals, dilated phloem rays, and banded phloem are unifying features. Mature nodal anatomy is 3-trace, trilacunar, and the leaves of both genera have elongate, unicellular, branched idioblasts in the spongy mesophyll. Bixa has some features in common with Amoreuxia and Cochlospermum but is distinctive in vascularization of the petiole, leaf anatomy, and vestiture. Rhopalocarpus is quite different from the above genera, and its placement in a separate family is justified on anatomical grounds. The Cochlospermaceae, consisting of Amoreuxia and Cochlospermum, seem more closely related to the Sterculiaceae and Tiliaceae than to the Flacourtiaceae, Cistaceae, or Violaceae.     

THE COAGULATION OF MYOSIN IN MUSCLE

1. Muscle can be prepared in the form of a dry powder in which myosin exists in a state similar to that in intact muscle. As in intact muscle, myosin in powdered muscle is soluble and can be caused to rapidly coagulate. 2. Restoring to powdered muscle the quantity of water previously removed causes coagulation of myosin. The rate of coagulation is considerably slower at 0° than at 20°. 3. Adding the powder to a large volume of dilute salt solution also results in coagulation. 4. The water soluble constituents of muscle can be removed from the powder without thereby causing coagulation. Coagulation occurs in water extracted muscle when it is suspended in a dilute salt solution. 5. Coagulation of myosin in muscle resembles the coagulation of myosin caused by dehydration. 6. Myosin coagulates readily only when it is imbedded in the structure of muscle. The significance for coagulation of the arrangement of myosin particles in muscle has been indicated.     

SURVEY OF SHOOT ORGANIZATION IN THE ARACEAE

Shoot organization is examined in 87 species from 29 genera representing all six subfamilies of the Araceae and of Acorus, which has been placed in a separate family. Within each taxonomic group examined, the details of shoot organization are presented, including the types of segments and articles which make up the shoot, the degree of expansion of leaf blades, and the placement of buds along the shoots. Literature on shoot organization of the 29 genera is reviewed. The degree of correlation between shoot organization characteristics and systematic groupings is examined, and the utility of these characteristics for systematics is evaluated. It is found that within the taxa observed, the pattern of shoot organization provides a distinctive “fingerprint” at the generic or sectional level, sufficient for determination of the group. Some patterns which appear are pointed out: taxa with bisexual flowers usually produce a single inflorescence at the terminus of a vegetative article. A few taxa with bisexual flowers produce pairs of inflorescences at the ends of articles. Multiple inflorescences (more than two) at an article terminus occur only among taxa with unisexual flowers. Multiple inflorescences are associated with anisophyllous or homeophyllous sympodial growth, while single or paired inflorescences are associated with homeophyllous or intermittent homeophyllous sympodial growth. These patterns might be understood as the result of selection for flexibility of reproductive effort and of seasonal reproduction.     

ESSENTIAL LEAF OILS IN REPRESENTATIVES OF THE AURANTIOIDEAE (RUTACEAE)

The distribution of essential leaf oils in representatives of 12 genera in the Aurantioideae has been studied by gas chromatography. Of the individual oil components, 40 were identified by retention times on two columns, augmentation, and some by IR spectrophotometry. Twelve groupings of components were established and these compared between the tribes Clauseneae and Citreae , among the subtribes clauseninae , balsamocitbinae , and citrinae , and between the “primitive” and the “near citrus group.” The essential oils conform to the botanical groupings, except for Pleiospermium in the citrinae and Murraya in the clauseneae. Fortunello crassifolia (Citbeae ), a possible garden hybrid, seems to be more closely related to the Clauseneae , the remote citroids, than to the near Citrus group. Atalantia also might be an intertribal hybrid with remote or other citroids. A specimen of Aeglopsis chevalieri (balsamocitbinae ) from Florida appears to be of hybrid origin with the parental source close to Citrus.     

STRUCTURE OF THE SHOOT APEX IN LACTUCA SATIVA

Histological observations of the leaf lettuce ‘Black Seeded Simpson’ showed the dormant embryo to possess two visible leaves and a flkat to slightly depressed plumular apex. Observations conducted over a 12-day period of germination and growth showed the development of L₁ and L₂, emergence of L₃ and L₄, and periodic changes in size of the apex which were associated with leaf emergence. Thus the dormant embryo of Lactuca appears to be considerably more advanced in development than was previously believed. The shoot apex appeared flat to slightly depressed at all developmental stages studied.     

STRUCTURE AND DEVELOPMENT OF THE SHOOT IN DOLICOTHELE

Boke , Norman H. (U. Oklahoma, Norman.) Structure and development of the shoot in Dolicothele. Amer. Jour. Bot. 48(4): 316–321. Illus. 1961.—A study of 2 species of Dolicothele reveals that although they have dimorphic areoles and a pattern of spine development similar to those of certain mammillarias, they share a significant number of ectomorphic and endomorphic characters with coryphanthas of the “vivipara group.” These include a tendency toward a cespitose habit; relatively large flowers; green fruits; pitted seeds; medullary vascular systems; forking of the main tubercle traces in the bases of the tubercles; lack of mucilage cells; thin-walled epidermis and hypodermis, both devoid of crystals; and large, druse-like crystalline aggregates in older parts of the pith and cortex. The evidence suggests that Coryphantha vivipara and closely allied species are the nearest extant relatives of Dolicothele. It would, therefore, seem inconsistent to return Dolicothele to Mammillaria unless an author's viewpoint were so conservative that he was willing also to return most, if not all, coryphanthas and escobarias to that genus.     

SUBCELLULAR AND SUBMICROSOMAL DISTRIBUTION OF GLYCOLIPID-SYNTHESIZING TRANSFERASES IN YOUNG RAT BRAIN

The subcellular and submicrosomal distributions of four glycolipid-synthesizing transferases were studied in young rat brains. (1) Two galactosyl transferases involved in the synthesis of cerebrosides, the cerebroside sulphotransferase which catalyses the synthesis of sulphatides, and the glucosyl transferase which plays an important role in the ganglioside biosynthesis were localized essentially in the microsomal fraction. Only low activities were detected in the crude mitochondrial and synaptosome-enriched fractions. (2) A comparison of the activities of these enzymes in the crude myelin and two myelin subfractions showed that the galactosyl transferases and the cerebroside sulphotransferase had similar activities in the crude myelin and myelin-like fractions. A considerable galactosyl transferase activity was found in purified myelin. In this respect these two enzymes were different from cerebroside sulphotransferase, whose activity was much lower in purified myelin. On the other hand, glucosyl transferase had a relatively low specific activity in all three myelin fractions. Analysis of different markers showed that the activities were considerably higher than those expected from the maximum microsomal contamination calculated. (3) Subfractionation of the microsomes demonstrated that the galactosyl transferases were more concentrated in the lower parts of the gradient, containing vesicles with attached ribosomes. Cerebroside sulphotransferase and glucosyl transferase were found predominantly in the upper and intermediate parts of the gradient, which were composed essentially of smooth-surfaced vesicles and membrane fragments. Chemical analysis of submicrosomal fractions confirmed the morphological observations.