Protonemal Morphogenesis of the Moss Tetraphis pellucida Hedw. in Culture and in the Wild

In axenic culture, the protonemal filaments of Tetraphis pellucidaderived from either spores and gemmae, or excised stems andleaves, share a mixture of attributes of chloronemata and caulonemata.Indirect immunofluorescence reveals that the tip cells containcortical and endoplasmic arrays of microtubules at interphase,and phragmoplasts associated with cell plate formation, butpre-prophase bands are absent. Protonemal plates originate fromthe same sites as filamentous protonemal side branches or directlyfrom young gemmae or excised stem fragments. These plates havea cylindrical base, the latter producing a single gametophorebud, and a unistratose lamina. The gametophores produce gemmacups in culture with the vegetative life cycle taking approximately28 d. Gibberellic acid (GA₃) has no visible effect on protonemal morphogenesiswhereas the auxin naphthalene acetic acid (NAA) suppresses plateand side branch formation. In the presence of kinetin the platesare callus-like and produce supernumerary buds. Abscisic acid(ABA) induces malformed plates and filaments with swollen cells,similar to those found in ageing cultures. Rhizoids are produced in abundance from gametophores and protonemalplates in nature but were never seen in culture. In the wild,rhizoids produce numerous protonemal plates and occasional gametophorebuds. The former are the main source of new shoots. The filamentousprotonemal phase in nature mainly comprises upright filamentscontaining one or more abscission cells. The protonemal plates in Tetraphis are homologous with thosein the allied genus Tetrodontium but are very different fromthose in Diphyscium and Sphagnum. Differences between cultureand nature are attributed to lower nutrient levels and irradiancesin the wild. Tetraphis pellucida, protonema, moss, morphogenesis, immunocytochemistry, gemmae, tip growth, vegetative reproduction     

Plastid Ontogeny in the Corolla Cells of Digitalis purpurea L. cv. Foxy

Initially the corolla plastids of Digitalis purpurea containsmall grana with negatively stained thylakoids. Degenerationof the grana, loss of chlorophyll and the transient accumulationof starch accompany corolla expansion Starch disappears by thetime the anthers dehisce and granular and amorphous phytoferrtindeposits become prominent in the stroma Concomitant with theseparation of the stigmatic lobes the thylakoid system is reducedto a central membranous network enveloping the phytofemtm aggregatesJust prior to corolla abscission the stroma becomes packed withplastoglobuh Although this developmental sequence closely resemblesthat for chromoplasts in yellow and red flowers, fruits andautumn leaves there is no synthesis of carotenoid pigments inthe corollas of Digitalis purpurea At maturity the plastidsare therefore best described as elaioplasts. Digitalis purpurea L., foxglove, corolla, plastids, elaioplasts, phytofemtin, ultrastructure, X-ray microanalysis     

The 1952 outbreak of encephalitis in California; vector control aspects

X-radiation remains the treatment of choice in most cases of leukemia and lymphoma, but new agents are playing an increasing role in therapy. Radioactive phosphorus does not produce radiation sickness and results with it are comparable to those of x-ray therapy in chronic leukemia. Urethane and nitrogen mustard may produce remissions in patients with chronic leukemia who have become resistant to radiation. Triethylene melamine may be administered orally with nitrogen mustard-like effects and is undergoing further trial. Aminopterin, ACTH and cortisone often cause short remissions in acute leukemia. Urethane is the best treatment available for multiple myeloma. Polycythemia vera is well controlled by radioactive phosphorus combined with venesection. Nitrogen mustard is often effective and triethylene melamine shows promise in Hodgkin's disease. Antianemic substances such as iron and liver extract are of no value in the treatment of anemia caused by leukemia, lymphoma and myeloma.     

The Effect of Pollination and Ethylene on the Colour Change of the Banner Spot of Lupinus albifrons (Bentham) Flowers

In Lupinus albifrons flowers the banner spot of the standardis initially coloured white or pale yellow. Two to three daysafter reaching the stage of full flower opening, this bannerspot develops a pinkish blush and is deep magenta after a further24 h. The development of this pigmentation is accelerated byexposure to ethylene in a concentration- and time-dependentmanner. Flowers with a pinkish banner spot produced the greatestamounts of ethylene and production was much lower in flowerswhich had either completed the colour change or in which thebanner spot colour remained unchanged. Treatments such as stigmaremoval or pollination increased the rate of ethylene production.Dissection of the flowers showed that while the banner spotis changing colour there is no change in the rate of productionof ethylene from the standard, i.e. from the banner spot orsurrounding tissue. The major sites of production at this timeare the keel and pistil. Isolated flowers withered within 2 d of removal from the plantand therefore did not show any change in the colour of the bannerspot unless exposed to ethylene. The increase in banner spotpigment was about fourfold when isolated floweres were exposedto ethylene (0·24 µl 1^–1): however, the increasewas less than twofold when isolated standards were exposed toethylene (0·27 µl I^–1). Application of silverthiosulphate (STS) to intact isolated flowers, as a 1 h pulseprior to ethylene exposure, partially prevented the pigmentaccumulation, whilst a continuous supply of STS reduced theethylene-induced colour change by approx. 50% Low concentrationsof cycloheximide (CHI) (0·01 mg ml^–1) reduced theaccumulation of pigment in the banner spot of ethylene-treatedflowers, and higher concentrations (1·0 mg ml^–1)completely prevented the ethylene-induced colour change. Ethylene, flower senescence, Lupinus albifrons, pollination     

Flower Development and Senescence in Digitalis purpurea L., cv. Foxy

Flowers of Digitalis purpurea L. cv. Foxy, take just over aweek to develop from the smallest buds and open. Both the anthersand the stigma are closed when the flower opens, the anterioranthers dehisce 2 days after flower opening and the posterioranthers a day later. The stigma opens 2 days later still andthe corolla remains attached for a further 2 days. The maximum size of the corolla is reached soon after openingand then remains constant. The fresh weight increases throughoutthe attached life of the corolla, whereas the dry weight reachesa maximum at flower opening and decreases during the remainderof the corolla's attached life. The content of antho-cyaninvaries greatly from spike to spike. In some spikes the maximumcontent is at flower opening, in others it is much later, butin all cases the loss of anthocyanin with ageing is very smalland the corollas are abcissed without visible wilting or fading.Maximum protein, RNA and glucose contents occur at, or soonafter, flower opening and the levels decrease in the corollasas they age. Fructose reaches a maximum at the same time asglucose but does not decrease as rapidly, so that fructose becomesthe major reducing sugar in the older corollas. Sucrose cannotbe detected in any flowers. Ethylene production increases steadilywith flower age, but the maximum production is recorded fromflowers which have recently ab-scissed the corolla regardlessof whether this occurs before detachment from the spike or withinthe collection tube.