METHOD FOR COMBINED ULTRASTRUCTURAL AND BIOCHEMICAL ANALYSIS OF NEURAL TISSUE

No significant change was found in the electrolytes and lipids of the brain analyzed after glutaraldehyde fixation by perfusion of laboratory animals; such fixation also satisfactorily preserves neural tissues for electron microscopy. The brains of normal and tumor-bearing C3H mice, Wistar rats, and New Zealand rabbits were studied. Little difference was found in the dry weight and the content of sodium, potassium, total lipid and lipid fractions, and in the sulfate space (S³⁵O₄) between specimens from unperfused and perfused animals, whether normal or tumor-bearing. The results suggest the possibility of using selected regions of the nervous system, dissected after fixation, for chemical study and at the same time characterizing similar regions morphologically with the electron microscope.     

The search for new industrial crops

Advances in technological development have produced an ever-increasing pressure for new and different raw materials to keep pace with changing industrial needs. Many new and useful properties of plants may be discovered through the modern chemistry and technology of utilization research. The U. S. Department of Agriculture’s search for new industrial crops is a coordinated botanical and utilization research program.     

SEROLOGICAL STUDIES IN BAPTISIA AND CERTAIN OTHER GENERA OF THE LEGUMINOSAE

Fourteen species of Baptisia were compared serologically, using antiserum against B. nuttalliana. By means of both immunoelectrophoretic and double-diffusion techniques, it was possible to disclose 11 distinct arcs plus some weaker arcs, with few reliable (definite and repeatable) differences detected among the species of Baptisia investigated. Since the individual species of Baptisia are often quite distinctive, as judged by other chemical and morphological criteria, the serological data are in this instance conservative and appear to be effective in circumscribing the genus. In contrast, striking interspecific differences in the serological properties of unicellular green algae have been obtained (reported elsewhere) by similar techniques in this laboratory. It is concluded that serological data should be regarded as adjuncts to other systematic knowledge only on the basis of empirical manifestations of their utility. There is no clear justification for regarding serological data as intrinsically either superior or inferior to other systematic criteria.     

Morphology and function of the Golgi apparatus

The polymorphism of the dictyosomes in the root meristeme ofFagopyrum is connected with their various functions in secretory processes and cell differentiation. The dictyosomes containing vesicular dilatations of the cisternae, which in this object occur more frequently than in others, probably participate in a similar way as the Golgi apparatus of the animal cell in the formation of lysozomes, in the formation of elements belonging to the group of dense bodies analogical lysozomes. These bodies are present in large numbers in the cytoplasm of cells, containing dictyosomes with vesicular dilatations. The other forms of the dictyosomes reveal indications of their participation in the production of the carbohydrate material of the cell walls, like most dictyosomes of other plant objects. However, no fusion of the Golgi vesicles with the plasmalemma was observed. According to their morphological appearance the typical forms of dictyosomes were classified on the basis of their relationship to secretory processes. Simultaneously the morphology and function of the Golgi apparatus was compared in the animal and plant cell. Several morphological varieties of the dictyosomes of plant cells, observed after the action of pathogenic factors and the effect of the fixation procedures, were also noticed in small quantities in the cells of the investigated objects.     

Amino ketone formation and aminopropanol-dehydrogenase activity in rat-liver preparations

1. Rat tissue homogenates convert dl-1-aminopropan-2-ol into aminoacetone. Liver homogenates have relatively high aminopropanol-dehydrogenase activity compared with kidney, heart, spleen and muscle preparations. 2. Maximum activity of liver homogenates is exhibited at pH9·8. The K_m for aminopropanol is approx. 15mm, calculated for a single enantiomorph, and the maximum activity is approx. 9mμmoles of aminoacetone formed/mg. wet wt. of liver/hr.at 37°. Aminoacetone is also formed from l-threonine, but less rapidly. An unidentified amino ketone is formed from dl-4-amino-3-hydroxybutyrate, the K_m for which is approx. 200mm at pH9·8. 3. Aminopropanol-dehydrogenase activity in homogenates is inhibited non-competitively by dl-3-hydroxybutyrate, the K_i being approx. 200mm. EDTA and other chelating agents are weakly inhibitory, and whereas potassium chloride activates slightly at low concentrations, inhibition occurs at 50–100mm. 4. It is concluded that aminopropanol-dehydrogenase is located in mitochondria, and in contrast with l-threonine dehydrogenase can be readily solubilized from mitochondrial preparations by ultrasonic treatment. 5. Soluble extracts of disintegrated mitochondria exhibit maximum aminopropanol-dehydrogenase activity at pH9·1 At this pH, K_m values for the amino alcohol and NAD⁺ are approx. 200 and 1·3mm respectively. Under optimum conditions the maximum velocity is approx. 70mμmoles of aminoacetone formed/mg. of protein/hr. at 37°. Chelating agents and thiol reagents appear to have little effect on enzyme activity, but potassium chloride inhibits at all concentrations tested up to 80mm. dl-3-Hydroxybutyrate is only slightly inhibitory. 6. Dehydrogenase activities for l-threonine and dl-4-amino-3-hydroxybutyrate appear to be distinct from that for aminopropanol. 7. Intraperitoneal injection of aminopropanol into rats leads to excretion of aminoacetone in the urine. Aminoacetone excretion proportional to the amount of the amino alcohol administered, is complete within 24hr., but represents less than 0·1% of the dose given. 8. The possible metabolic role of amino alcohol dehydrogenases is discussed.