Changes in the population dynamics of Keratella cochlearis (Gosse), Kellicottia longispina (Gosse) and Polyarthra vulgaris Carlin in a fertilized enclosure

The population dynamics of phytoplankton and zooplankton in a fertilized enclosure were studied from April 1977 to June 1978. During the first spring period, the rotifers Keratella cochlearis, Kellicottia longispina, and Polyarthra vulgaris were scarce. During the following spring, all three species were abundant. An attempt is made to explain these differences. Food resource competition from cladocerans, and the low food quality and possible inhibitory effects of Coccomyxa sp. were found to be the most likely factors limiting the growth of these rotifers during the first spring period.     

Single potassium channels in membranes of isolated mesophyll barley vacuoles

Summary Voltage-dependent K channels could be identified in on-cell and excised patch-clamp records on membranes of isolated plant cell vacuoles. The current through a membrane patch is dominated by a channel population with a conductance of about 121 pS in symmetrical 250mm KCl solution. The single channel adopts at least two conducting levels the 121-pS state being most frequently observed. The channel shows outward rectification, representing a cation flux into the vacuoles. The rectification appears to be caused by a vanishing open probability and a short channel lifetime at hyperpolarizing voltages. A selectivity ratio of potassium over sodium of about 6 was derived as an estimate. Occasionally, an additional population of K channels with a single-channel conductance of approximately 18 pS is observed. This channel type exhibits outward rectification as well.     

A phylogenetic study of the antenna cleaner in Formicidae,Mutillidae, and Tiphiidae (Insecta,Hymenoptera)

Summary The morphology of the tibio-tarsal antenna cleaner (strigilis) of 30 species of Formicidae, 14 species of Mutillidae and 9 species of Tiphiidae was investigated and is described comparatively. In Formicidae, there is a common type of strigilis. The spur has a posterior-dorsal comb and its anterior side is covered with squamae, which usually form a brush. Posteriorly, the basitarsal notch bears a comb and anteriorly specialized paddle-shaped hairs. These characters may be apomorphic for Formicidae. In several Ponerinae and in Myrmecia there is also a velum on the spur. In two species of ants which are strongly parasitic (Teleutomyrmex schneideri and Anergates atratulus ) there are reduced antenna cleaners. Mutillidae (except Myrmosa) have another common type of strigilis: the spur bears a velum with a smooth rim and a clear apex with two rows of teeth. The notch in the basitarsus is usually deeper than that of ants; there is a comb, but no paddle-shaped hairs. The strigilis of Myrmosa females has no velum but there are two prominent rows of teeth on the spur. In the male, the velum is reduced to a slender strip. In Tiphiidae the antenna cleaners show considerable diversity. In Methocha the spur bears a comb but no velum; the spur of Tiphia has a velum with a serrated rim; the spur of Myzinum is equipped with a velum with a smooth rim; in Thynnus the surface of the velum is wrinkled or undulating. An apex (without teeth) is present in all investigated Tiphiidae. The notch of the basitarsus bears a comb except in female Myzinum, where the teeth seem to have fused, thus forming a rim. It is suggested that a velum with a serrated or toothed edge and an apex with two rows of teeth are plesiomorphic for aculeate Hymenoptera. The antenna cleaners in Mutillidae are remarkably similar to those in some bees. This fact is interpreted as partly due to convergence and as partly symplesiomorphic. In several species of ants, there is a specialized cuticular area (bande poreuse) anterior to the comb of the notch, which is characterized by fissures or holes. These are presumably openings of an excretory gland.     

Naturally occurring monoterpenoids in needles of Picea abies (L.) Karst

Summary An analysis was made of the effects of different sampling and extraction techniques on the amounts and pattern of monoterpenoids isolated from needles of Norway spruce. The following isolation and analysis procedure was finally adopted: liquid nitrogen-cooled needles were pulverized by a microdismembrator, extracted with pentane overnight at 2°–3°C and concentrated to a volume not less than 3 ml/g fresh weight on a Vigreux column. The crude extract was injected splitless (with solvent split) onto a cold programmed temperature vaporized (PTV) precolumn of a gas chromatograph and the vaporizable compounds heated to a capillary column. This method was tested for production of artefacts and quantitative extraction and applied to needles of eleven 80-year-old spruce trees.     

Concentration gradients of free sterols,steryl esters and lipid phosphorus in the trunkwood of Scot's pine (Pinus sylvestris L.)

The amounts of free sterols, steryl esters and lipid phosphorus were determined in the sapwood and heartwood of mature, and in the outer and inner sapwood of young Pinus sylvestris trees. In the mature trees (up to 70 years old) the heartwood contains significantly higher amounts of free sterols than the sapwood. No radial gradient can be demonstrated in the amounts of steryl esters. Lipids extracted from the sapwood contain higher amounts of phosphorus than those from the heartwood. Stems of young Pinus sylvestris trees (up to 13 years old) show in the inner sapwood higher amounts of both free sterols and steryl esters than the peripheral younger wood zone. The inner sapwood of the young stems shows slightly higher amounts of lipid phosphorus than the outer sapwood. The results indicate that Pinus sylvestris accumulates both free sterols and steryl esters in the stems at a very early stage of the life cycle. Sterol accumulation in the innermost parts of the stems seems not to depend on heartwood formation.     

Immunohistochemical procedures for the demonstration of peptide- and tyrosine hydroxylase-containing nerve fibers in cryostat sections of unfixed rapidly frozen tissue stored for long periods of time

Summary Traditional protocols for the immunohistochemical localization of peptides and tyrosine hydroxylase (TH) in nerve fibers in cryostat sections require the tissue to be thoroughly fixed and rinsed and to be processed for the cryostat sectioning and the immunohistochemical staining more or less directly after freezing. In the present study it was tested whether also unfixed, rapidly frozen tissue, conforming to guinea pig and bovine heart specimens, can be used for the visualization of neuropeptides [neuropeptide Y (NPY) and substance P (S P)] and TH in cryostat sections. The following observations were made: 1) NPY-immunoreactive (IR) and S P-IR nerve fibers could be clearly identified in both fixed and unfixed sections of this type of tissue. 2) TH-IR nerve fibers could be detected in unfixed tissue if the sections were post-fixed with aldehydes by the use of a two-step fixation process related to a sudden change of pH. However, the outlines of the nerve fibers were sometimes diffuse. 3) Storage of unfixed tissue for periods of up to 2.5 yeart at –80° C did not lead to a decrease in immunoreactivity. 4) Somewhat higher concentrations of primary antibodies had to be used for sections of unfixed tissue than for sections of fixed tissue when the FITC method was used. This waste of antibodies was partly overcome by use of the biotin-streptavidin method. The glyoxylic acid induced catecholamine(CA)-fluorescence method for demonstration of sympathetic nerve fibers was also applied and was found to give optimal results after storage of tissue for up to 2.5 years. The study shows that the use of unfixed rapidly frozen tissue represents a fast and realistic method for the demonstration of neuropeptide immunoreactivity, that it to some extent can be used for the visualization of TH-containing nerve fibers and that it is a suitable method to maintain longterm neuropeptide and TH immunoreactivity as well as long-term CA-fluorescence reaction.     

Betaine Transport Imparts Osmotolerance on a Strain of Lactobacillus acidophilus

Unlike most Lactobacillus acidophilus strains, a specific strain, L. acidophilus IFO 3532, was found to grow in rich medium containing 1 M sodium acetate, KCl, or NaCl. This strain could also grow with up to 1.8 M NaCl or 3 M nonelectrolytes (fructose, xylose, or sorbitol) added. Thus, this strain was tolerant to osmotic pressures up to 2.8 osM. A search for an intracellular solute which conferred osmoprotection led to the identification of glycine betaine (betaine). Betaine was accumulated to high concentrations in cells growing in MRS medium supplemented with 1 M KCl or NaCl. Uptake of [¹⁴C]betaine by L. acidophilus 3532 cells suspended in buffer was stimulated by increasing the medium osmotic pressure with 1 M KCl or NaCl. The accumulated betaine was not metabolized further; transport was relatively specific for betaine and was dependent on an energy source. Other lactobacilli, more osmosensitive than strain 3532, including L. acidophilus strain E4356, L. bulgaricus 8144, and L. delbrueckii 9649, showed lower betaine transport rates in response to an osmotic challenge than L. acidophilus 3532. Experiments with chloramphenicol-treated L. acidophilus 3532 cells indicated that the transport system was not induced but appeared to be activated by an increase in osmotic pressure.     

Membrane H+ Conductance of Clostridium thermoaceticum and Clostridium acetobutylicum: Evidence for Electrogenic Na+/H+ Antiport in Clostridium thermoaceticum

H⁺ conductance in de-energized cells of Clostridium thermoaceticum and Clostridium acetobutylicum was determined from the rate of realkalinization of the medium after an acid pulse. In both organisms, cell membrane proton permeability was increased by fermentation end products and ionophores. In C. thermoaceticum, H⁺ conductance was increased by Na⁺ ions compared with K⁺ as counterions. In these cells, addition of Na⁺, but not K⁺, elicited efflux of H⁺; H⁺ efflux was stimulated by SCN⁻ and decreased by various ionophores. We concluded that C. thermoaceticum possesses an electrogenic Na⁺/H⁺ antiporter. In contrast, C. acetobutylicum cells did not have an electrogenic Na⁺/H⁺ antiporter.     

Genetic variability in mitochondrial DNA in a regional population of the great tit (Parus major)

Genetic variation of mitochondrial DNA (mtDNA) in 18 great tits (Parus major) from three neighboring localities in Sweden was investigated with eight tetranucleotide restriction endonucleases. The 18 individuals could be separated into 13 different maternal lineages. The high number of female lineages present in this regional population contrasts with a low level of sequence divergence between the different mtDNA clones, with a mean of 0.19% sequence divergence between all individuals. There was no obvious spatial structuring of mtDNA clones among the three localities. The presence of a high number of different clones with a low degree of sequence divergence could be explained by the effects of a large long-term effective population size, with the mtDNA clones having diverged about 25,000–200,000 years ago.This study was supported by the Swedish Natural Science Research Council, the Erik Philip-Sörensen Foundation, and the Nilsson-Ehle Foundation.