DEVELOPMENTAL STUDIES OF ERYTHROCLADIA ROSENVINGE IN CULTURE

Erythrocladia subintegra has been cultured for over 3 years. The life history includes reproduction by monospores, a long period of ameboid motility by monospores, their germination and growth into monostromatic disk-shaped plantlets composed of adherent, often dichotomously branched filaments. Plants become centrally polystromatic with age and produce monospores. Variations in plant size and shape, cell size and shape, spore size, shape, and motility are discussed. Variations in plants of E. subintegra grown on different substrates have been studied and discussed in relation to other species in the genus.     

DISTRIBUTION,SEASONALITY AND REPRODUCTIVE PHENOLOGY OF BANGIA ATROPURPUREA (RHODOPHYTA) IN RHODE ISLAND,U.S.A.1

Forty-seven sites along the Rhode Island coastline were sampled on a seasonal basis for the presence of the red alga Bangia atropurpurea (Roth) C. Ag. This species was found to be widely distributed, occurring at 94% of the hard, stable substrates sampled. Bangia populations were most, widespread in the winter (71% of sites) and least frequent in the summer (29% of sites). At one location, three high intertidal populations (average height 101 cm) and three low intertidal populations (average height 14 cm) were sampled monthly for two years. The upper intertidal populations appeared in September and persisted until at least May, whereas the lower populations were ephemeral, appearing for only a few months in late winter. The high intertidal populations were present on 85% of the sampling dates white the lower ones were observed on 25% of the sampling dates. Upper intertidal filaments reproduced exclusively by asexual monospores unlike those of the lower populations which were largely sexual. The maximum diameter of asexual and carpogonial filaments was 120 and 250 nm, respectively. Monosporagenesis was strongly correlated to temperature whereas gametogenesis was strongly correlated to photopriod.     

DISTRIBUTION AND SALINITY ADAPTATIONS OF BANGIA ATROPURPUREA (RHODOPHYTA), A PUTATIVE MIGRANT INTO THE LAURENTIAN GREAT LAKES1

In a survey of the distribution of Bangia atropurpurea (Roth) Ag. along the north and east shorelines of the Laurentian Great Lakes, it was observed that this species was concentrated in the lower lakes. Asexual reproduction by monospore formation was the only form of reproduction in these populations. First generation germlings derived from these spores grew in a wide range of salinities from 1 to 26‰, but the rate was inversely proportional to salinity. In addition, acclimation of parent plants to freshwater or marine media prior to sporulation affected growth rates of first generation germlings placed into a series of salinities. By the second and third generation, germlings with a lineage of seawater showed a preference for the higher salinities, 19 and 26‰ Plants collected in Lake Ontario exhibited no decline in photosynthetic rate as salinity was raised by 13‰ for 15 min. At 26‰ the rate was reduced by half and thylakoids were disrupted in the region of the pyrenoid. On the other hand, third generation plants with a history of seawater attained maximum photosynthetic rates at 26‰ and contained a normal thylakoid organization. Three chromosomes were observed in these plants, which agrees with some of the previous findings for marine Bangia. Origins and taxonomic status of Bangia growing In the Great Lakes are discussed in light of these findings.     

EFFECTS OF PHOTOPERIOD AND KIND OF SUPPLEMENTAL LIGHT ON GROWTH,FLOWERING, AND STEM FASCIATION OF CELOSIA

Piringer , A. A., and H. A. Borthwick . (U.S.D.A., Beltsville, Md.) Effects of photoperiod and kind of supplemental light on growth, flowering and stem fasciation of Celosia. Amer. Jour. Bot. 48(7): 588–592. Illus. 1961.—Four cultivars of Celosia argentea L. var. cristata were grown on photoperiods ranging from 8 hr to continuous light. Supplemental low-intensity incandescent light was used to extend 8 hr of natural light and provide the given photoperiod. In all cultivars, short main stems occurred on photoperiods of 12 or fewer hours and long main stems, due to more nodes, on photoperiods of 16 or more hours. Flowering was a nonobligate short-day response in all cultivars. Plants of certain cultivars tended to have shorter stems and flower later when 8 hr of fluorescent instead of incandescent light was used to provide the 16-hr photoperiod. In 3 of the cultivars studied, photoperiods of 16 or more hours induced marked stem fasciation.     

IS THERE AN ECOPHYSIOLOGICAL EXPLANATION FOR THE GAMETOPHYTE–TETRASPOROPHYTE RATIO IN GELIDIUM SESQUIPEDALE (RHODOPHYTA)?1

In the fall, when 61% of the fronds of the Gelidium sesquipedale (Clem.) Born. et Thur. population located in Albufeira (southern Portugal) were reproductive, about 90% of these fronds were tetrasporophytes, whereas an equal percentage of female and male gametophytes was found (5%). The comparison of physiological performances of the reproductive phases (males, females and tetrasporophytes) did not reveal a physiological advantage of tetrasporic fronds. There were no significant differences either in the photosynthesis, nitrogen uptake, nitrate reductase activity, or biochemical composition of adult fronds. On the other hand, vegetative recruitment and spore production in the laboratory were significantly different. The re‐attachment to calcareous substrate and the subsequent rhizoidal growth were faster in tetrasporophytes. Particular levels of temperature, rather than irradiance, had an important effect on the phase differences in the spore release, attachment, and germination rates. Significant results were the higher release of carpospores at all irradiances at 17°C, and the higher attachment percentage of carpospores at 13°C versus tetraspores. Under higher temperatures (21°C), tetraspores showed higher attachment rates while carpospores germinated more. G. sesquipedale cystocarps released carpospores for 2 months, while tetrasporangia stopped shedding tetraspores after 1 month, resulting in a 3‐fold higher production of carpospores than tetraspores. Results showed that vegetative and spore recruitment may explain the low gametophyte–tetrasporophyte ratio of the studied population of G. sesquipedale as opposed to the physiological performance of phases.     

INTERACTION OF LIGHT QUALITY AND NUCLEASES IN THE GROWTH OF THE GAMETOPHYTES OF ASPLENIUM NIDUS

Appropriate concentrations of ribonuclease A and B selectively inhibited initiation of two-dimensional morphology in the gametophytes of Asplenium nidus, grown under a photoperiod of 5½ hr white light. Filamentous growth was promoted in such sporelings, the individual cells of which were significantly longer than corresponding cells of the control. Higher concentrations of enzymes were required to inhibit two-dimensional growth in the gametophytes grown in blue light. Concentrations of ribonuclease A or B which inhibited two-dimensional growth in white light promoted growth in length of the protonema in red light. Growth modifications in the sporelings induced by deoxyribonuclease in different light conditions were similar to those induced by the ribonucleases. The results lend further support to the postulated role of RNA in the regulation of two-dimensional growth in fern gametophytes.     

INDETERMINATE GROWTH OF PERICARPS IN THREE MEMBERS OF THE RHODYMENIALES (RHODOPHYTA)12

Pericarps generally are thought of as structures having determinate growth, serving as a protective covering for the developing gonimoblast. In laboratory culture, the pericarps of Champia parvula (C. Agardh) Harvey, Lomentaria baileyana (Harvey) Farlow and Lomentaria sp. exhibited indeterminate growth. These tissues could be excised and grown as separate female plants. The new plants were indistinguishable from the parent tissue, were fertile, and produced viable carpospores.     

CULTURE AND DEVELOPMENTAL MORPHOLOGY OF COMPSOPOGON COERULEUS

Compsopogon coeruleus has been grown in culture for 4 years. The life-history consists of reproduction by monospores and their germination and growth into erect filamentous (corticated or uncorticated) thalli. Plastids are parietal sheets in young cells but undergo characteristic divisions to form discoid segments in older cells. The chromosome number has been determined as 7 ± 1. Sporangia have been studied and their derivation compared to the sporangial types of Drew-Baker. Variations in cell walls, basal systems, spore germination and young plantlets are discussed.     

THE CONCHOCELIS PHASE OF THREE SPECIES OF PORPHYRA IN CULTURE

The Conchocelis phases of Porphyra perforata f. patens, P. cuneiformis and P. nereocystis were cultured from spores in a sterile artificial medium at 12 C and with 25 ft-c illumination for 10 hr daily. The cultures showed differences in duration of the vegetative phase, sporulation, liberation of spores, and the return to the leafy phase. Morphological differences were also noticed. Since the 3 species were grown under identical conditions, it is inferred that these characteristics are probably different for the 3 species studied.     

Effects on Growth and Toxin Production of Exposure of Spores of Clostridium botulinum Type F to Sublethal Doses of Gamma Irradiation

Spores of the Langeland strain of Clostridium botulinum type F were grown at 30 or 10 C after exposure to 0.0, 0.1, or 0.2 megarad of cesium-137 gamma irradiation. When incubated at 30 C, cultures irradiated at the 0.2-megarad level reached the stationary growth phase 15 hr earlier than the 0.0 or 0.1 megarad-irradiated cultures. This was not the result of earlier or more frequent germination of the irradiated spores, the formation of larger individual cells, filament formation, or cell clumping. It appeared to result from elimination of a lytic phenomenon noted in 0.0 and 0.1 megarad-irradiated cultures after 26 and 29 hr of incubation, respectively, which was followed by a second exponential-growth response 5 hr later in these cultures. The time of toxin appearance in culture supernatant fractions was independent of prior irradiation treatment and occurred after 36 hr of incubation. Toxin release was essentially logarithmic until maximal titers were reached and maximal toxin titers were higher in irradiated than in unirradiated cultures. The higher toxin level was sustained over a period of 23 days of 30 C. Toxin produced in the 30 C cultures could not be trypsin-activated. An incubation temperature of 10 C resulted in no outgrowth of spores subjected to 0.2 megarad of irradiation, although spore germination did occur. At 10 C, outgrowth of the 0.1-megarad culture was faster with slightly higher quantities of a more stable toxin than was seen in the unirradiated control. At 10 C, trypsinization was necessary to demonstrate the toxin present in the cultures.     

KARYOTYPES AND REPRODUCTIVE SEASONALITY OF THE GENUS BANGIA (RHODOPHYTA) IN BRITISH COLUMBIA,CANADA1

Chromosome number and morphology as well as reproductive seasonally were examined in Bangia populations collected from 88 sites along the British Columbia coasts. Sexual filaments were recorded at 35 sites and asexual filaments at 58. Four different types of Bangia were determined. These were characterized by reproductive state and chromosome number, as well as by their seasonally and range of distribution. A summer-fall three-chromosome sexual type occurred from approximately 50° N northward and a winter-spring four-chromosome sexual type had a northerly limit of approximately 54° N, extending to the southernmost areas of British Columbia. Two asexual types occurred, exhibiting little seasonally, six-chromosome populations throughout the coast and three-chromosome populations at three southerly sites only. Karyograms were prepared for the four chromosomal types, assigning tentative centromere locations. Somatic chromosome pairing was reported for the first time in the Rhodophyta.     

THE EFFECT OF DAYLENGTH AND LIGHT INTENSITY ON THE GROWTH RATE OF THE MARINE DIATOM DETONULA CONFERVACEA (CLEVE) GRAN1

The influence of 40 combinations of temperature (2, 7 C), light intensity (50, 200, 600, 1200, 1800 ft-c), and photoperiod (24, 15:9, 12:12, and 8:16 LD) at 30% salinity on the rate of cell division of the Narragansett Bay clone of Detonula confervacea (Det-1) was examined following appropriate preconditioning. At 2 C Detonula is a long day species (24 L) and prefers low light intensities (200–600 ft-c); poorest growth occurred at 12:12 and 8:16 LD, and the compensation intensity was about 10 ft-c. Increasing temperature to 7 C increased the mean growth rate, reduced the optimal daylength (15:9 LD), even though Detonula remained a long day species and increased the optimal light intensity (600–800 ft-c). The compensation intensity varied with daylength and ranged from about 10–50 ft-c. Photoperiods of 12:12 and 8:16 LD were least favorable for growth at both temperatures; light limitation and inhibition were observed at 50 and 1800 ft-c. respectively; inhibition was less pronounced at 7 C. There is some indication that the conditions of growth that the stock cultures were exposed to prior to preconditioning for use in the experiments may have sometimes influenced response. Detonula produced resting spores without nutrient depletion at 2 and 7 C at all light intensities when the photoperiod was lengthened. Auxospore formation was also observed. Although short daylengths (9:15 LD) limit Detonula's growth during the early stages of the winter bloom, it competes successfully against Skeletonema costatum initially. This results from its higher rates of growth and of photosynthesis at the prevailing temperature and light conditions and a lower compensation intensity than reported for Skeletonema. The main causes of Detonula's growth inception and termination in Narragansett Bay differ.     

LIFE HISTORY AND HYBRIDIZATION STUDIES ON GIGARTINA STELLATA AND PETROCELIS CRUENTA (RHODOPHYTA) IN THE NORTH ATLANTIC1

Fourteen isolates of the crustose marine red alga Petrocelis cruenta J. Agardh from various localities in the British Isles, France (including the type locality), Spain and Portugal gave rise in culture to dioecious foliose plants identifiable as Gigartina stellata (Stackhouse) Batters although two isolates formed only sterile foliose blades. A total of 145 isolates of Gigartina stellata were also grown in culture from various localities in the U.S.A. (Maine), the British Isles, Iceland, Denmark, France, Spain and Portugal using both carpospores and vegetative blade apices. Two basic types of life history were found among these isolates: a direct-type life history involving the formation of further foliose plants from carpospores, some isolates of which also form spermatangia on the same papillae as the cystocarps; and a heteromorphic-type in which only crustose plants resembling Petrocelis cruenta are formed from carpospores. Only heteromorphic-type life histories were found from Spain and Portugal. Both life history types were found in plants from the U.S.A., the British Isles and northern France. Only direct-type life histories were found in plants from Iceland and Denmark. Some Petrocelis-like crusts derived from field collected G. stellata carpospores and Petrocelis crusts of hybrid progeny formed tetrasporangia in 8:16 h LD, 10° C but not in 8:16 h LD, 15° C; 16:8 h LD 10° C or 15° C; and 10:6.5:1: 6.5 h LDLD, 10° C. The spores thus formed were viable and produced normal dioecious male and female gametophytes. Short day and low temperature conditions appear necessary for tetrasporogenesis. The results from crossing experiments with 32 male and 27 female isolates of the heteromorphic-type derived from both G. stellata and P. cruenta showed that two virtually non-interbreeding populations with a high degree of geographical separation exist in the north-eastern Atlantic. Morphological differences between plants from each population are described. On the basis of culture and crossing results, Petrocelis cruenta J. Agardh is placed in synonymy with Gigartina stellata (Stackhouse in Withering) Batters.     

Spore production and mycorrhizal development in various tropical crop hosts infected with Glomus clarum

Plant growth, mycorrhizal development and vesicular arbuscular spore production were examined in five tropical crop host species inoculated with Glomus clarum and grown in a glasshouse. In one of the two experiments, sequential harvests of maize, sorghum and chickpea were made in order to study spore production in relation to plant growth and mycorrhizal development. Spore numbers in each of these hosts increased at a fairly constant rate until maximum plant dry weight, when spore production ceased. Sorghum and maize produced considerably more spores than chickpea, with spore numbers being closely correlated with mycorrhizal root length. In the second experiment, Glomus clarum was cultured on each of maize, millet, sorghum, groundnut and chickpea for three consecutive generations before cross-inoculation of the spores from each host onto all five hosts. Sporulation with respect to host size was generally greatest when the inoculum used to infect a host had been produced on that host. The growth-promoting effects of the fungus were not influenced by the source of the inoculum. More spores were produced on the cereals than the legumes. Differences in spore numbers amongst hosts and plant generations were apparently influenced mainly by infected root length and by the growth period.     

Spore discharge in the red algae Bostrychia tenella and Caloglossa leprieurii from the Godavari estuary,India

Bostrychia tenella (Vohl.) J. Ag. and Caloglossa leprieurii (Mont.) J. Ag., two examples of species important for human consumption from estuaries in Asia, were studied with respect to spore formation and release with a long-term view to their mass cultivation. Plants were collected between January and December 1987 from three different regions of the Gautami Godavari estuary, India. Both species behaved rather similarly. Tetrasporophytic plants were present throughout the year, whereas carposporophytic plants were found only in certain months. Shedding of tetraspores was observed throughout the year, but with seasonal difference in their output. Carpospores were liberated from October to May when the material was available. Maximum shedding of carpospores and tetraspores was observed in December and January and the minimum number of tetraspores in August and carpospores in May. The maximum number of spores was liberated, when plants were submerged at 20% salinity.     

OBSERVATIONS ON THE SURVIVAL AND GERMINATION OF RESTING SPORES OF THREE CHAETOCEROS (BACILLARIOPHYCEAE) SPECIES1,2

Resting spores (hypnospores) of Chaetoceros diadema (Ehrenberg) Gran, Chaetoceros vanheurckii Gran, and Chaetoceros didymus Ehrenberg were collected from a large plastic enclosure moored in Saanich Inlet, B.C., Canada. The effects of combinations of temperature and irradiance on the germination of these resting spores were investigated. Nutrient uptake, carbon fixation, and changes in the photosynthetic capacity of the germinating spores were also examined. Resting spores germinated optimally at combinations of temperature and irradiance similar to those in the environment during sporulation. They did not germinate at irradiances 1.3 μEin m^?2 s^?1 or temperatures >25.3° C. Nitrate, phosphate and silicate were taken up after the resting spores had germinated and resumed vegetative growth. Chlorophyll a fluorescence in vivo, and the DCMU-induced increase in in vivo fluorescence also increased after the resting spores had germinated. Resting spores began to fix carbon as soon as they were placed in light. Spores remained viable for at least 645 d. The length of time between first exposure to light and germination did not change during this period; however, the percentage of viable resting spores decreased markedly. None of the Chaetoceros spores germinated after 737 d of storage at 2–4° C in darkness.     

EXPERIMENTAL HYBRIDIZATION OF XANTHIUM STRUMARIUM (COMPOSITAE) FROM ASIA AND AMERICA. I. RESPONSES OF F1 HYBRIDS TO PHOTOPERIOD AND TEMPERATURE

Responses to photoperiod and temperature were compared for hybrids between Asiatic plants in the indigenous strumarium morphological complex and plants in five American complexes: oviforme, italicum, chinense, cavanillesii, and pennsylvancium. The F₁ hybrids between Hong Kong plants and various American plants showed intermediacy in photoperiodic response; however, the hybrid night requirement was more similar to that of the American parent. The Hong Kong plants are difficult to evaluate photoperiodically but showed a night length requirement of 9.25–9.50 hr. Day-neutral plants from India in the strumarium complex produced day-neutral F₁ hybrids in crosses with most American plants having night requirements less than 10 hr. The F₁ hybrids involving the day-neutral Indian plants and either Indian or Australian chinense plants showed a night requirement of 8.25–8.75 hr. The chinense parental plants had apparent critical nights of 10.25–10.50 hr. Crosses between the day-neutral Indian plants and Mexican plants with apparent critical nights of 10.75–11 hr produced F₁ hybrids requiring nights of 8.75–9.00 hr. The various hybrids tended to show the broader temperature tolerances of the American parents. The ripeness-to-flower (maturity) responses of seedlings tended to show the genetic controls of the parent with the faster developmental rate. The hybridization evidence suggests that photoperiodic responses are quantitatively controlled and inherited independently of morphology and ripeness-to-flower responses. The populations of India are highly diverse and probably reflect recombinations of photoperiodic and temperature responses between indigenous day-neutral plants and photoperiodic chinense plants introduced from North America.     

ROLE OF SETTLEMENT DENSITY ON GAMETOPHYTE GROWTH AND REPRODUCTION IN THE KELPS PTERYGOPHORA CALIFORNICA AND MACROCYSTIS PYRIFERA (PHAEOPHYCEAE)1

Laboratory studies were used to examine how variation in the density of spore settlement influences gametophyte growth, reproduction, and subsequent sporophyte production in the kelps Pterygophora californica Ruprecht and Macrocystis pyrifera (L.) C. Ag. In still (non-aerated) cultures, egg maturation in both species was delayed when spores were seeded at densities 300 · mm^?2. Although the density at which this inhibition was first observed was similar for both species, the age at which their eggs matured was not. P. californica females reached sexual maturity an average of 4 days (or ～ 30%) sooner than did M, pyrifera. As observed previously in field experiments, per capita sporophyte production was negatively density dependent for both species when seeded at spore densities of 10 · mm^?2. Total sporophyte production (i.e. number · cm^?2) for both species, however, was greatest at intermediate densities of spore settlement (～ 50 spores · mm^?2). In contrast, total sporophyte production by P. californica steadily increased with increasing spore density in aerated cultures; highest sporophyte density was observed on slides seeded at a density of 1000 spores · mm^?2. Preliminary experiments with P. californica involving manipulation of aeration and nutrients indicate that inhibition of gametophyte growth and reproduction at higher densities of spore settlement in non-aerated cultures was probably caused by nutrient limitation.     

Porphyra drewiana, a new species of red algae (Bangiales, Rhodophyta) from Brazil

Porphyra drewiana Coll et Oliveira, sp. nov., is described from plants collected on the south‐east coast of Brazil. The species proposed is monostromatic, monoecious, monoplastidial, without marginal microscopic teeth and does not produce monospores. Both phases, leafy and filamentous, have three chromosomes. Morphologically the most similar species is Porphyra spiralis Oliveira et Coll var. amplifolia Oliveira et Coll, from which it differs by: (i) thallus gross morphology; (ii) scattered pluristromatic areas of vegetative cells; (iii) division of the plastids prior to the nucleus at the first division of the carpospores mother cell; (iv) the number of carpospores and spermatia produced per mother cell; and (v) morphology and behavior of the filamentous phase in cultures. An identification key for the species referred to Brazil is included.     

CO-REQUIREMENT FOR CALCIUM AND POTASSIUM IN THE GERMINATION OF SPORES OF THE FERN ONOCLEA SENSIBILIS

Spores of Onoclea sensibilis L. do not germinate on distilled H₂O if they are pretreated for sufficient time with dilute NaClO solution. However, spores will germinate, after NaClO pretreatment, on a simple mineral medium containing the major and trace elements. Complete germination after pretreatment also is obtained on a solution containing only Ca²⁺ and K⁺ as the cations, but neither ion by itself is sufficient. Rb⁺, but not Li⁺ or Na⁺, can replace K⁺. Hypochlorite-treated spores do not require the continuous presence of Ca²⁺ and K⁺ to germinate; exposure during the first 4 hr of culture, with the remainder of the time on distilled H₂O, is sufficient. Extraction of spores with ethylene glycol bis(aminoethyl ether) tetraacetic acid [EGTA] makes their germination dependent on Ca²⁺, as reported by other workers, but it does not produce a co-requirement for K⁺. Colorimetric analysis with arsenazo III confirms that Ca²⁺ is extracted from Onoclea spores by NaClO. Extractable Ca²⁺ amounts to about 78 nmol/mg spore dry wt. Of this amount, 31% is contained in the perispore. The perispore comprises 13% of the total spore dry wt.