Proton extrusion in seed coats of Phaseolus vulgaris L.

Abstract. The present investigations were designed to identify proton pumps in seed coats of Phaseolus vulgaris L. Vacated seed-coat halves were exposed to bathing solutions with indicators for proton pump action and the pH changes in the media were measured. Fusicoccin increased the rate of proton extrusion from the seed coats. Orthovanadate and abscisic acid retarded the proton extrusion evoked by fusicoccin. Abolition of the proton extrusion by parachloromercuriphenylsulphonic acid was partially reversed by diethioerythritol. The extrusion was stimulated by high osmolarities (100 mol m⁻³ sorbitol), potassium ions (100 mol m⁻³ KCI) and light. Old seed coats reacted more rapidly to fusicoccin treatments than young ones. Proton pumping in seed coats and cotyledons showed differential responses to fusicoccin, K⁺ and sucrose. In contrast to seed coats, medium acidification by cotyledons was prohibited by addition of sucrose. The significance of proton pumps for photosynthate transfer in vivo is discussed.     

Development of the macro-invertebrate fauna of Cow Green reservoir (Upper Teesdale) in the first five years of its existence

SUMMARY. The development of marginal (shore-line), sub-littoral (3–6 m) and profundal (15–18 m) fauna was followed using timed collections in shallow water and artificial substrata in deeper regions. The reservoir started filling in July 1970 and was close to top water level in the autumn of that year. Samples in the marginal zone contained drowned terrestrial organisms and some Cladocera (Chydoridae) in February 1971 but by October, Chironomidae and Oligochaeta became abundant and micro-crustaceans (copepods and cladocerans) formed about 98% of the total catch. Peak densities of micro-crustaceans in the marginal zone were reached in the summer of 1971, but chironomids and oligochaetes were most abundant in the second year after filling. The numbers of marginal zone animals were greatest at the most sheltered site, and lowest at a site on the windward shore. At a stream mouth the rheophilic fauna present in April 1971 was replaced with limnophilic organisms (Chironomidae and Tubificidae) by September 1971. In the sub-littoral, Hydra, Enchytraeidae, Orthocladiinae Tanytarsini and oribatoid mites were the most abundant taxa, whereas Naididae, Hirudinea, Ostracoda, Gammarus pulex, Chironomini and Pisidium spp. were numerous in the profundal zone. Total faunal numbers and biomass were greatest in the profundal zone in all years. The highest annual mean estimate of biomass in the sub-littoral was 3.07 g (wet wt)m^?2 in the second year after filling, thereafter both numbers and biomass fell. In the profundal the maximum biomass (about 29 gm^?2) was observed in the third and fourth years after filling. An estimate of total standing crop of benthic organisms below the drawdown limit, made in July 1974, gave a figure of about 43 tonnes, wet weight. Biomass estimates at Cow Green were compared with those in eighteen other reservoirs and were found to be high especially in relation to those from other upland areas.     

Direct Transmission of a Hemoflagellate,Cryptobia salmositica (Kinetoplastida: Bodonina) Between Rainbow Trout Under Laboratory Conditions1

Transmission of Cryptobia salmositica occurred when infected and uninfected rainbow trout were held in the same tank. In tanks where infected and uninfected fish were allowed to mix freely, 67–80% of the uninfected fish acquired detectable infections by the 27th week. None of the control fish in another tank was infected. In another tank where the infected and uninfected fish were separated by a wire screen, 9 of 20 uninfected fish acquired detectable infections by the 22nd week. This is the first demonstration of direct transmission of a hemoflagellate via the water medium in aquatic vertebrates. Cryptobia salmositica was found in the mucus on the body surface of 9 of 10 fish examined 6 weeks after infection. These parasites were infective and some of them were morphologically similar to those in the blood or peritoneal fluid. It is suggested that the vascular species of Cryptobia were originally ectoparasitic on fishes and that these ectoparasitic species were descended from the free-living Procryptobia.     

The mesolophe, a new lophophore type for chonetacean brachiopods

Rachebaeuf, P. R. & Copper, P. 1990 10 15: The mesolophe, a new lophophore type for chonetacean brachiopods. Lethaia , Val. 23, pp. 341–346. Oslo. ISSN 0024–1164.
Following a summary of previous lophophore reconstructions for the chonetaceans, we describe an unusual pyritized structure within the calcite infill of an exceptionally preserved shell of Archeochonetes primigenius (Twenhofel) from the Late Ordovician (Ashgill) of Anticosti Island, Quebec, Canada. The brachial valve interior of most Lower Devonian to Permian chonetaceans shows the development of three depressed deepened areas (gutters) in the valve floor. The disposition of these gutters coincides remarkably with the shape of the pyritized structure, which we postulate as a new type of lophophore, the mesolophe. ▭ Brachiopoda, Chonetacea, functional morphology, lophophore .     

The Translocation of Lead and Copper in Two Submerged Aquatic Angiosperm Species

The translocation of lead and copper was studied in two speciesof submerged aquatic angiosperm, Potamogeton crispus L. andPotamogeton pectinatus L. A perspex container incorporatinga potters' clay seal around the stems of intact plants was designedfor the chemical separation of the shoot and root environmentsduring 11–21 d treatment periods. Metal solutions wereadded to the root or shoot environments and concentrations weremonitored in waters and sediments. A technique was developedfor the direct quantitative analysis of metals in small (0.02–0.2mg) segments of water plant tissue, using the graphite rod attachmentto an atomic absorption spectrophotometer. Experimental resultsindicated minimal translocation of lead, but extensive acropetaltranslocation of copper to particular sites of accumulation.     

Tyrosinase Autoactivation and the Problem of the Lag Period

Evidence is presented for the binding of the quinone oxidation product of the monohydric phenol substrate, 4-hydroxyanisole, to mushroom tyrosinase. Column chromatography and SDS-PAGE separation showed labelling of the enzyme when incubated with ¹⁴C ring-labelled 4-hydroxyanisole. It is proposed that covalent binding to the enzyme and other proteins is through reaction of accessible nucleophilic groups, including thiols and amino groups, with the anisylquinone. This reductive addition enables the indirect generation of the catecholic substrate, which acts as an electron donor for the bicupric active site of met-tyrosinase and explains the lag kinetics of tyrosinase oxidation of non-cyclizing substrates. The effects of diluting the enzyme or the addition of amino acids on the lag period was consistent with a mechanism involving indirect generation of the dihydric phenol, which acts as the met-enzyme-recruiting substrate.     

Mating systems in the Lapwing Vanellus vanellus

The Lapwing Vanellus vanellus has traditionally been regarded as a monogamous, single brooded species, defending a single territory. Recent studies involving individually recognizable Lapwings have begun to challenge the ubiquity of these statements, with high frequencies of polygyny and the production of second broods being reported. Breeding Lapwings were studied in Upper Teesdale, County Durham, U.K., between 1993 and 1995, where both adults and chicks had been individually colour-ringed since 1990. A total of 90 territorial males and 64 females were intensively studied during the 3 years. Overall, 30% of territorial males had more than one mate in any year, with 19% more adult males than yearling males mating polygynously. On two occasions, polygynous males simultaneously defended two territories. Five females attempted to produce second broods, and one was polyandrous.     

The Cellular Pathway of Short-distance Transfer of Photosynthates and Potassium in the Elongating Stem of Phaseolus vulgaris L. A Structural Assessment

The potential cellular pathway of radial transfer of photosynthateand potassium delivered in the phloem to the elongation zone(apical 0.5–2.5 cm) of internode 2 ofPhaseolus vulgarisL. seedlings was elucidated. This was achieved using ultrastructuralobservations of the cell types that constitute the radial pathwayand estimates of potential sucrose and potassium fluxes throughthe cross-sectional area of interconnecting plasmodesmata andacross the plasma membrane surface areas of selected cell types.The investigation relied on predicting the relative roles ofthe mature and developing sieve elements as conduits for theaxial delivery of solutes to the elongation zone. In turn, thesepredictions led to formulation of two transport models whichwere subsequently evaluated. It was found that unloading ofsucrose and potassium from the protophloem sieve elements cannotbe through the symplast due to the absence of plasmodesmata.On the other hand, mature metaphloem sieve element-companioncell complexes have the potential capacity to unload eitherthrough the stem symplast or apoplast. The potential symplasticroute is proposed to be via the companion cells to the adjacentlarge phloem parenchyma cells. Continued radial transfer couldoccur either by exchange to the stem apoplast from the largephloem parenchyma cells or continue in the symplast to the groundtissues. It was further predicted that sucrose utilized forthe development of the procambial/small phloem parenchyma cellscould be delivered axially by them and not by the mature sieveelements. Phaseolus vulgaris ; apoplast; elongating stem; photosynthates; potassium; transport; symplast