摘要:

ABSTRACTCentroceras internitensn. sp. (Rhodophyceae, Ceramiaceae) was found in the Florida Keys and Bermuda only as an epiphyte onCeramium nitens(C. Agardh) J. Agardh. It is described on the basis of many collections, including an abundance of reproductive material representing all stages of the life history. Laboratory culture has not been successful. The type locality is a well‐known limestone platform on the Atlantic Ocean side of West Summerland Key, Florida Keys. In addition to living material,C. internitenswas found on eight herbarium specimens ofCeramium nitensat the United States National Museum, thereby establishing records of its occurrence throughout the Caribbean Sea and dating back to 188

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1983.00261.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTThe relationship of cell organelles to valve morphogenesis was investigated in three species ofNitzschia.One,N. sigmoidea(Nitzsch) W. Sm., showed consistent ability to generate both nitzschioid and hantzschioid symmetry in daughter cells following cytokinesis; the other two maintained nitzschioid symmetry stably. From previous work withHantzschia, a certain sequence of events could be anticipated in the cytoplasm. In two significant areas–the behavior of the Microtubule Center (MC) and its microtubule (MT) system, and the central origin of the silicalemma–not only were the results unexpected, but the three species showed fundamental differences among themselves. InN. sigmoidea, the silicalemma (and the future raphe region) arises centrally on the cleavage furrow, and after some lateral expansion, the silicalemmas and their associated organelles move in opposite directions in daughter cells, so that the raphe and the raphe canals end up along the girdle side of the cell as expected. However, the MCs never become associated with their silicalemma, remaining throughout near the girdle bands. InN. sigma(Kütz) W. Sm., the silicalemmas arise centrally and after lateral growth, move in opposite directions to generate nitzschioid symmetry. In this case, the MCs move to the vicinity of but never close to the silicalemmas, and follow them distantly during their lateral movement. InN. tryblionellaHantzsch, the new silicalemmas arise opposite one another, on one side of the daughter cells; each MC soon moves very close to its silicalemma, and remains thus through most of valve morphogenesis. Later, only one silicalemma/MC complex moves laterally, establishing the nitzschioid symmetry in both daughter cells. In all three species, as inHantzschia, linear arrays of mitochondria aligned along MTs occupy the forming raphe canal, and microfilaments line the outer edge of the expanding silicalemma. The fibulae (the wall struts arching across the raphe canal) inHantzschiaalways grow from the valve surface to the girdle surface of the forming valves. In these threeNitzschiae, this invariably happens in only one daughter cell of any pair; in the other, all the fibulae grow from the girdle surface to the valve surface. An explanation of these variations is proposed: that the morphogenetic machinery ofNitzschiaandHantzschiahave a common origin, with presentNitzschiaehaving undergone considerable diversification at the intracellular level, causing the unstable cell symmetry exhibited by several modern species. Perhaps a taxonomic distinction betweenHantzschiaandNitzschialies in whether the morphogenetic machinery associated with valve morphogenesis moves laterally in the same or in opposite direct

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1983.00269.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTThree species ofNaviculaare described from light and scanning electron microscopy.Navicula bottnicaGrunow, has not previously been illustrated at the SEM level, nor has it previously been reported to form colonies, but the cells appear to be identical toSchizonema smithiiC. Agardh (sensu van Heurck) and the name is amended toNavicula smithii(C. Ag.) van Heurck. The colonies are irregularly branched, the cells within forming strands which frequently appear braided. Material ofN. delogneivan Heurck differs in several points from typical material and a new form,ellipticais proposed. Observations on the third species,N. pseudocomoidescorroborate recent work by Cox in Britain.

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1983.00281.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTWe analyzed 34 strains representing 25 species of Chrysophyceae for chlorophylls c1and c2using thin‐layer chromatography. Most organisms had both chlorophylls c1and c2in addition to chlorophyll a but 17 strains of 9 species ofSynuraandMallomonaspossessed only chlorophylls a and c1. These are the first chlorophyll c‐bearing algae which lack chlorophyll c2. We postulate that at least some of the silica‐scaled algae includingMallomonasandSynuramay be distinct from other Chrysophyceae based upon pigmentation and other characters described in the liter

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1983.00289.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTMicrotubule involvement in diatom valve symmetry and pattern formation was investigated using cells synchronized subsequent to mitosis and cytokinesis but prior to cell wall formation. Two analog drug pairs, each consisting of an active and an inactive microtubule drug, were used to distinguish inhibitory effects related or unrelated to microtubule disruption. The active anti‐microtubule drug of each analog pair produced significantly higher percentages of aberrant valves than did the respective inactive analogs. High frequencies of aberrant valves also were caused by N‐isophenlpropylcarbamate, which disorganizes rather than disrupts microtubules. Valves could be placed into different classes based upon characteristic aberrations. Formation of these classes was not random but was instead a function of both the drug and the drug concentration. The central nodule and the raphe were the principal valve components affected by anti‐microtubule drugs. Stria alterations appeared as a secondary result of alterations in the central nodule/raphe. Valve aberrations occurred at very low drug concentrations in the range 1 × 10−6to 1

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1983.00294.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTA laboratory study was conducted, to examine and compare the sensitivity of vegetative cells and zygospores ofChlamydomonas moewusiiGerloff to 20 different herbicides. Under the culture conditions employed, both vegetative growth and zygospore germination were affected by certain herbicides and not by others. Over a concentration range from 1.0–80.0 μM, growth was inhibited to various degrees by herbicides containing ametryne, paraquat, endothall, diquat, diuron, linuron, propanil, dinoseb, ioxynil, atrzine, prometon, and alachlor. Zygospore germination was inhibited significantly by herbicides containing dinoseb, endothall, parquet, diquat, propanil, linuron, ioxynil, ametryne, fenac and picloram at 80.0 μM concentrations. Comparisons of the results obtained indicate that concentrations of herbicides which affect growth may or may not effect zygospore germination and vice versa. Zygospores may be more resistant than vegetative cells to some but not all herbici

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1983.00301.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTThe validity of a recent nutrient‐based modal of algal photosynthesis was tested using phosphorus‐limited semi‐continuous cultures of the green alga,Scenedesmus quadricauda.The data suggest that light‐saturate photosynthesis (Popt, mg C · mg chla−1· h−1) is a hyperbolic function of cellular phosphorus quota (Qp), whether Qp is expressed per unit cellular chlorophyll a, per unit dry weight, or per cell number. Furthermore, the light availability during growth appears to have little effect on these hyperbolic relationships over the range of light intensities studied here (65–110 μE · m−2· s−1). These data, and data presented from other published studies, suggest that the cell quota model is a valid empirical description of the photosynthetic behavior of

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1983.00306.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTChlamydomonas reinhardtiiDang, was grown in a chemostat culture under phosphate limitation. The steady state concentration of phosphate was below the detection limit (0.12 h−1) and became attached to the wall of the culture vessel. They differed from the vegetative stage in both chemical composition and growth rate. Their contents of phosphorus and chlorophyll a were low, as in the vegetative cells, which grew at a low growth rate, whereas the ration Qpp/Qpand the activity of alkaline phosphatase were comparable with those of fast growing vegetative cells. The growth rate of the palmelloids was 0.03 h−1whereas maximum growth rate (μm) for the vegetative cells was 0.2

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1983.00313.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTNavicula mutica(Kütz.) var.muticawas isolated from the air, cloned on agar, cultured in soil‐water bottle, and studied with transmission and scanning electron micros‐ropy. The frustules were lanceolate to ovoid with rounded apices, with the apical axis 8.5 ± 3.2 μ and the trans‐apical and the transapical axis 3.6 ± 0.6 μm. Striae were composed of two or three puncta, and the mantle bore a single row of puncta aligned with the striae. The ends of the raphe turned away from an isolated punctual in the central area of the valve. The mantle puncta and one or two of the valve‐face puncta in each stria opened into a series of transapical grooves in the interior of the valve, the grooves contributing to the appearance of striae in the light microscope. The interior of the mantle also possessed a pair of longitudinal grooves, discontinuous at the apices of the valves. An undulate advalvar margin of the valvocopula likely articulates along the interior longitudinal groove of the mantle. The projections of the undulate margin are perhaps positioned between the transapical grooves and along the longitudinal groove between the dentiform structures formed by the intersection of the double‐grooved system. The girdle bands each had two (occasionally three) rows of pores. The pleurae margins were straight an

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1983.00320.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTBatrachospermumplants collected as part of a comprehensive study of New England streams were found to be intermediate betweenB. boryanumSirdt. findB. ectocarpumSirdt. Sixty‐four specimens from ten Rhode Island streams were examined for several characteristics in replicates of two to four hundred. The size ranges obtained were then compared with previous published data forB. boryanumandB. ectocarpum fromEurope, Asia and North America. The Rhode Inland populations and individuals exhibited as much or even more variability as that reported for both species combined throughout the world. Therefore, it appears that there is no definite basis for separation of these taxa and it is proposed that they be merged under the nameB. boryanum.This combined species ran be distinguished from other species of the sectionBatrachospermumby compressed mature lateral whorls, little secondary fascicle formation, curved distal branching, terminal hairs on a small proportion of branches, predominantly dioecious state, sessile trichogynes and carposporophytes in outer portions of lateral whorl

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1983.00324.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY