Paul R. Burkholder

Antibiotic Activity of some Marine Algae of Puerto Rico

Antibiotics of marine organisms have received little attention up to the present, in comparison wlth the antimkrobial substances produced by land organisms. Whereas, during the past decade thousands of papers were published about the inhibitory products of terrigenous microbes, only about a score of contributkms have appeared on various aspects of aquatic antibiotks. For the purpose of orientation, a few representative papers dealing with antimicrobial substances in aquatic organisms will be discussed here briefly. Among early contributions to the Hterature on algal antibiotics was the series of papers by Prat t and colleagues, who described the production and activity of the fatty acid chlorellin, that accumulates in cultures of the green alga Chlorella vulgaris (See Prat t , 1948). Another interesting example of inhibitory substances among fresh water algae is found in the antibiosis demonstrable between Haematococcus and Chlamydomonas (Proctor, 1957). The presence of antibiotic substances in seaweeds was reported by Pra t t and colleagues (Pratt et al. 1951) and also by Vacca and Walsh (1954). It was suggested by Mautner , Gardner and Pratt (1953) that the active substance in Rhodomela larix may be a brominated phenol. More recently a contribution has appeared on antibacterial activity of ether extracts from British seaweeds (Chesters and Stott , 1956), among which Halidrys siliquosa^ Pelvetia canaliculatay L·am^nar^a digitata^ and Polysiphoma fastigiata were especially noteworthy. A biological study of antimicrobial marine algae at Kiel (Ross, 1957) showed that among 27 species, the most active were the followmg: Fucus serratusy Rhodomela subfusca^ Desmarestia aculeata, and Delesseria sangmnea. Pertinent references on the ecology of antibiotic substances may be found in the review of Bryan (1957). Another interesting discussion of growth-promoting and inhibiting substances in the sea has been published by Nigrelli (1958). An unusal case of antibacterial action was studied by Burkholder and Burkholder (1958) in gorgonian corals, which are algal-polyp symbionts, in some ways physiologically similar to the terrestrial symbiotic lichens. Antibacterial activity in marine phytoplankton has been demonstrated in Antartica recently by Sieburth (1959) and Sieburth and Burkholder (1959). The antibioticproducing alga in Antartic waters is Phaeocystis Poucheti, which is eaten by Euphausia* that in turn is the staple diet of penguins. The gastrointestinal microflora of penguins appears to be modified by their antibiotic foodstuffs.

Productivity of Microalgae in Antarctic Sea Ice

Midsummer productivity of Antarctic microalgae, commonly occurring in brown sea ice along the west coast of the Palmer Peninsula, averaged more than 900 milligrams of carbon per cubic meter per hour, with an assimilation number of about 2.6. The rate of photosynthesis increased with light intensity to a maximum of about 18,000 lux, above which some inhibition was observed. The floral composition, genesis, and physiological properties of these ice communities are different from the epontic under-ice diatoms previously studied by other investigators in McMurdo Sound.

Atypical Growth of Plants. I. Cultivation of Virus Tumors of Rumex on Nutrient Agar

1. Virus wound tumors of Rumex acetosa were cultivated satisfactorily in a chemically defined medium containing inorganic salts, sucrose, B vitamins, and agar. Best growth was obtained in media with relatively high concentrations of nitrate and phosphate, sucrose 2-3%, agar 1%, and with the pH value adjusted to about 5.2. 2. The tumor consists of small parenchymatous nodules, containing meristematic zones and some differentiated elements, loosely held together to form a disorganized mass which has never been observed to differentiate normal plant organs. 3. When the tumor was grafted onto leaves of healthy Rumex plants, enlarged veins and tumefaction of the roots resulted. 4. This virus-infected tumor tissue, showing rapid growth and having apparent stability in a simple basal medium, provides valuable experimental material for further study of problems in the fields of virology and growth and development.

Polarized Growth and Cell Studies in the First Internode and Coleoptile of Avena in Relation to Light and Darkness

1. Twenty varieties of three species of Avena were germinated in complete darkness and with preliminary light treatment in the early stages of soaking, followed by growth in darkness. The ratio of internode length to coleoptile length differed markedly in the different varieties. 2. Final length of the first internode of Avena sativa var. Victory grown under a series of different intensities of weak Mazda light varied inversely with the intensity. Similar inhibition of internode elongation in proportion to the intensity of Neon light was found at intensities below 0.1 erg/mm.2/sec. 3. Early stages of germination in Victory oats in light (1000 watt Mazda) and in darkness showed that the internode elongated slightly during early swelling (up to thirty-six hours) in both light and darkness. In darkness further polarized growth occurred in the internode, but in strong light growth ceased early and shifted to the coleoptile. 4. Different amounts of light influenced polarized growth in different organs and tissues in different ways. Very low intensities of light inhibited growth of the first internode but not that of the coleoptile; high intensities inhibited the internode and appreciably shortened the coleoptile (by decreasing the number of cells as well as cell length). In complete absence of light the internode grew extensively, and the coleoptile was somewhat shorter than in plants which received small amounts of light in the early stages of germination. 5. Analyses of cell behavior in the first internode when grown to maturity under different intensities of Mazda light indicated that both cell division and cell enlargement were responsible for polarized growth. 6. During early germination, cell enlargement (up to a certain size) was found to occur in the first internode whether the seedlings were grown in light or darkness; in later development, cell division occurred in darkness and under very low intensities but not in bright light. The size of dividing cells during early germination in darkness was somewhat less than that attained by the cells of internodes grown in light. 7. In darkness, both cell division and cell elongation contributed to growth of the internode in length. The number of internode cells increased from embryo to maturity by 8.5 times and the average cell length increased by 30 times. 8. The effect of light in shortening the first internode of the axis was brought about primarily by inhibition of cell division. It is suggested that the influencing factors are probably concerned with certain substances necessary for cell division, and if so, such substances must be rendered ineffective, or are changed in their path of movement, by very low intensities of light.

SOME CHEMICAL CONSTITUENTS OF TURTLE GRASS, THALASSIA TESTUDINUM

Primary biological productivity in the coastal waters of Puerto Rico is based upon the synthetic processes of phytoplankton, benthic algae, mangroves, corals and the turtle grass, Thalassia testudinum. A considerable portion of the total production of organic matter in this region appears to be contributed by the large beds of Thalassia, widely scattered at depths of less than five meters, over well-illuminated, shallow bays, channels, and inner margins of coral reefs. These studies have been initiated in order to find out more about the magnitude, chemical composition, and possible value of Thalassia to the marine life of tropical regions. Some simple comparisons of proximate analyses are made between Thalassia, and other primary crops of grasses from Georgia, and phytoplankton from Long Island Sound. Standing crop. Determinations of the standing crop of Thalassia were made at representative stations near La Parguera during February of 1958. A special cutting instrument was used to obtain samples of plants including leaves, rhizomes and roots, from a uniform area of one square foot. Samples were washed in a sieve, dried in an oven at 1000C, and weighed. Typical results of the determinations are shown in Table 1. The range of

The rôle of light in the life of plants

Relation of light to biological processes . . . . . . . . . . . . . . . . . . . 2 Photosynthesis . . . . . . . . . . . . . . . 6 ChlorophyU formation . . . . . . . . 7 Other pigments . . . . . . . . . . . . . . . 11 Chromatic adaptation . . . . . . . . . 13 Photodynamic action . . . . . . . . . 15 Transpiration . . . . . . . . . . . . . . . . . 16 Absorption and use of solutes . 17 Permeability . . . . . . . . . . . . . . . . . 20 Protoplasmic movement . . . . . . 21 Assimilation . . . . . . . . . . . . . . . . . . 21 Carbohydrate/nitrogen ratio .. 25 Inorganic elements . . . . . . . . . . . . 30 Acidity, stomatal movement, etc. 32 Photoperiodic stimulation . . . . 34 Reduction/oxidation ratio . . . . 38 Enzymes . . . . . . . . . . . . . . . . . . . . . 41 Vitamins . . . . . . . . . . . . . . . . . . . . . 42 Seed germination . . . . . . . . . . . . . 44 Growth-substances . . . . . . . . . . . . 47 Electrical potential . . . . . . . . . . . 49

Atypical Growth of Plants. III. Growth Responses of Virus Tumors of Rumex to Certain Nucleic Acid Components and Related Compounds

1. Virus tumors of Rumex acetosa L. (sorrel) containing the virus Aureogenus magnivena Black were grown in culture in a chemically defined medium with various additions of nucleic acids, or their components, and related compounds. 2. Growth was enhanced by the addition of alkaline-hydrolyzed ribosenucleic acid in the range of 0.2-0.8 mg/ml and decreased by comparable levels of alkaline-hydrolyzed desoxyribosenucleic acid. 3. Marked inhibition was observed in media containing adenine, adenosine, or adenylic acid. 4. Some evidence of stimulation was observed in media containing guanine, uracil, xanthine, or hypoxanthine. At concentrations of 0.3 or 0.4 mg/ml of medium, 6-ketopurine (hypoxanthine) was stimulatory; 2,6-diketopurine (xanthine) less beneficial; and 2,6,8-triketopurine (uric acid) definitely toxic. 5. The triazolo analogue of guanine was inhibitory at all levels tested down to 0.001 mg/ml. This inhibition was progressively reversed by guanine added over a range from 0.01 to 0.30 mg/ml.

Specificity of Microbiological Attack on Cellulose Derivatives

Data have been presented relating to the growth of 11 species of microorganisms isolated from deteriorated cotton fabrics on various derivatives of glucose, mannose, cellobiose, and cellulose. A high degree of specificity was exhibited. As long as there was at least one firmly bound substituent in every anhydroglucose unit, the resulting derivative was not susceptible to microbiological attack. Under such conditions the nature of the substituent has relatively little influence on the degree of resistance imparted. This was considered to be promising theoretical support for the underlying premise on which the idea of multipurpose topochemical reactions as a means of mildewproofing cotton fabrics was proposed.

Movement in the Cyanophyceae

The effect of pH upon the velocity of translatory movement of Oscillatoria formosa Bory in inorganic culture solutions was determined. Unhindered movement occurred in the range of about pH 6.4 to 9.5. Above and below these limits inhibition was marked. In the unfavorable acid and alkaline ranges inhibition was progressive with exposure time; in the favorable range continuous movement was maintained for 24 hours.

The rôle of light in the life of plants II. The influence of light upon growth and differentiation

CONTENTS Growth . . . . . . . . . . . . . . . . . . . . . . 97 Light and darkness . . . . . . . . . 98 Cell multiplication . . . . . . . . . . 102 Cell enlargement . . . . . . . . . . . 105 Action of growth substance. 110 Growth os the plant as a whole . . . . . . . . . . . . . . . . . . 113 Light intensity . . . . . . . . . . . . 114 Light duration . . . . . . . . . . . . 118 Light quality . . . . . . . . . . . . . 120 Differentiation . . . . . . . . . . . . . . . . 123 The plant axis . . . . . . . . . . . . . 124 Growth regions . . . . . . . . . . . . 128 Tissue differentiation . . . . . . . 129 Leaves . . . . . . . . . . . . . . . . . . . . . 130 Reproduction . . . . . . . . . . 9 . . . . . 134 Sex reversal and rejuvenation . . . . . . . . . . . . . . . . . . . . . . 140 Differentiation of the plant as a whole . . . . . . . . . . . . . . . . . . 142