摘要:

ABSTRACTComparison of exudation rate of medullary conducting cells in the midrib ofAlaria esculenta(L.) Grev. showed lowest rates for the blade meristem and highest rates in the non‐growing region, 300–500 mm from the meristem. Holding plants under continuous darkness or severing the wings from the midrib reduced exudation rate by 26 and 37%, respectively. Osmotic pressure of exudate in sink (meristem) and source (non‐growing region, up to 500 mm from the meristem) were similar (34.6–36.1 · 102kpa). Pressure flow mechanism of translocation is evaluated

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1978.tb00631.x

出版商:Blackwell Publishing Inc    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTNew structural details of the frustules of the diatomTriceratium favusEhrenberg seen in the scanning electron microscope are reported. Significant new observations concern the pores of the hexagonal chambers, accessory structures (spines, dendritic processes) on the outer surfaces of the hexagonal chambers, the value margins and girdle structure.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1978.tb00632.x

出版商:Blackwell Publishing Inc    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTBacteriastrum furcatumShadbolt,Chaetoceros bacteriastroidesKarsten andC. pseudocurvisetumMangin are each connected in chains by fusion of silica between setae. The first two have specialized heterovalvate end cells indicating physiological control of the length of chains, but chains ofC. pseudocurvisetumhave usually been seen broken. There are specialized deeply lobed connecting bands inB. furcatumandC. pseudocurvisetum,allowing the setae of sibling valves to protrude outside the diameter of the chain during their formation.C. bacteriastroidesandC. pseudocurvisetumare not identical; differences include presence of small setae, fusion of large setae some distance from the valves, symmetry of apertures between cells, and straight chains ofC. bacteriastroides,compared with valve mantle connections with no small setae, large setae joined by crossing over, asymmetry of windows between cells, and curved chains ofC. pseudocurvisetum.The evolutionary direction is hypothesized to be fromBacteriastrumtoChaetocerosthroughC. bacteriastroides.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1978.tb00633.x

出版商:Blackwell Publishing Inc    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTGymnodimium breveDavis, an unarmored marine dinoflagellate has a cell covering (theca) composed of four membranes. The inner two membranes represent a vesicular layer and in tangential section, the theca appears composed of polygonal areas. Unusual threat ridges are located in the cingular region between the epi‐ and hypocone. This osmotically sensitive species is extremely vesiculate with dispersed areas of cytoplasm containing typical eukaryotic organelles as well as other organelles found only in dinoflagellates. The non‐vesiculated cytoplasm is continuous in serial sections. The chloroplasts can contain either quasi‐radial or parallel lamellae typically consisting of three thylakoids each. The pyrenoid is multiple‐stalked and lacks a starch cap. The dinophycean pusule is simple and similar to those found in several unarmored marine species. The nucleus is typically dinophycean but the chromosomes appear to lack nonfibrillar m

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1978.tb00634.x

出版商:Blackwell Publishing Inc    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTThe uptake of glucose and amino acids by the euryhaline diatomCyclotella crypticaReimann, Lewin&Guillard does not appear to be related to proton gradients. Instead, the transport systems for these organic solutes show a strong requirement for the presence of NaCl. The relationship between uptake and NaCl concentration is hyperbolic, with optimal uptake rates being approached at 100 mM NaCl. High concentrations of KCl cause strong reductions in uptake rates. The (Na+, K+)‐stimulated ATPase inhibitor ouabain has no effect on glucose uptake, whereas the diphenolic glucoside phlorizin and its aglucone phloretin are strongly inhibitory. The proton translocating uncoupler CCCP (carbonylcyanidem‐chlorophenyl hydrazone) and the ATPase inhibitor DCCD (dicyclohexylcarbodiimide) both almost completely abolish glucose transport, and low concentrations of the ionophares monensin and valenomycin strongly inhibit glucose uptake by the diatom. The requirement of high external NaCl concentrations for glucose transport, and the inhibitory effect an transport of the Na+‐specific ionophore monensin are consistent with a coupling of Na+and organic substrate transport, but could also be explained by a Na+requirement for glucose binding to a transport carrier, and/or a possible interference with energy producing reactions associated with a monensin‐induced collapse of the normal Na+g

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1978.tb00635.x

出版商:Blackwell Publishing Inc    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTA crustose, nodular mat, primarily composed ofCalothrixsp. andPleurocapsasp., occurs in some alkaline hot springs of the western United States. Together, these species constituted ca. 71% of the mat biomass; the remainder was partitioned between other cyanophytes and bacteria. Their temperature growth ranges in culture were 24–50 C(Calothrix)and 30–55 C(Pleurocapsa).Both clonal cultures had maximal growth rates at 45 C(Pleurocapsa,1.28 doublings/24 h; Calothrix2.30).Calothrixgrew at approximately twice the rate ofPleurocapsathroughout their coincidental temperature range. The relative proportions ofCalothrix(42%) andPleurocapsa(27%) were constant in a thick mat (ca. 1 mm) regardless of season; however, a thin mat (ca. 0.5 mm) contained significantly morePleurocapsa(71%) and lessCalothrix(5%). Analysis of 10 μm thick microtome sections showed thatPleurocapsadominated the innermost region (substrate side) of the nodule mat whileCalothrixabundance increased from ca. 3% in this region to 80–96% at the surface of thick mat samples (ca. 0.8–2.3 mm). Our proposed that the grazing pressure exerted by an ostracod population accounts for the continued coexistence of and the observed spatial relationships between these species appears most consistent with the obse

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1978.tb00636.x

出版商:Blackwell Publishing Inc    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTKCl soluble carrageenans from sporophytes of twoGigartinaspecies were differentiated from those ofChondrus crispusStackhouse,Iridaea cordata(Turner) Bory,Rhodoglossum californicum(J. Ag.) Abbott, and twoPetrocelisspecies by their failure to precipitate on immunodiffusion against either of two absorbed anti‐λ–carrageenan antisera. The carrageenans have been analyzed by infrared spectroscopy, and on this basis it is postulated that the antibody preparations recognize sulphate on C‐6 of the carrageenans. TheGigartinacarrageenans appear to lack sulfate at this po

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1978.tb00637.x

出版商:Blackwell Publishing Inc    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTThe reproductive structures ofGracilaria foliifera(Forsk.) Børg. from England and an unnamed species ofGracilariafrom Nova Scotia were studied by light microscopy. These two entities are distinguishable on the basis of the type of gonimoblast tissue in their mature cystocarps. This, together with other evidence, suggests that these are separate taxa

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1978.tb00638.x

出版商:Blackwell Publishing Inc    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTIn laboratory experiments discs cut from thalli ofUlva fenestrataPostels&Ruprecht grew in diameter and biomass (dry weight and ash‐free dry weight) more when dead leaves ofZostera marina L.were present than when absent. A maximum increase in dry weight of 500% in 14 days occurred withZosterapresent compared with only a 200% increase with no detritus. When NO−3and PO3‐4were added the weight of anUlvadisc increased by over 800% whenZosterawas present but by only 400% in controls. In general penicillin G (475 units/ml) caused a reduction in algal growth in cultures containing detritus. It is concluded that bacteria on the detritus may compete with algae for nutrients but by releasing unknown substances the bacteria promote the growth o

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1978.tb00639.x

出版商:Blackwell Publishing Inc    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTCultures of freshwater algae, representing three algal divisions,Synura peterseniiKorshikov; Chlamydomonassp.: andNitzschiasp., were subjected to four different mercury‐temperature shock interactions to demonstrate synergistic effects between mercury and temperature. Algal growth, measured by temporal changes in vivo fluorescence of chlorophyll was used to ascertain the effects. Mercury addition and temperature shock had various inhibitory effects on algal growth. Prior environmental conditions influence the effect of subsequent treatments. Growth ofS. peterseniiwas severely inhibited by mercury in all experiments. Control cultures would not grow at 30 C and died when shacked at this temperature.Chlamydomonassp. cultures initially inhibited by mercury were able to recover under most conditions after a period of reduced growth.Nitzschiasp. was resistant to mercury except when simultaneously shocked with temperature. Mercury analyses showed that Nitzschia cells at 25 C and 30 C contained a high percentage of the mercury initially added to the cultures. There was a significant loss of mercury at the end of each experiment from all cultures, probably due to volatilizatio

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1978.tb00640.x

出版商:Blackwell Publishing Inc    

年代:1978

数据来源: WILEY