Effects of Iron-, Manganese-, or Magnesium-Deficiency on the Growth and Morphology of Euglena gracilis1

Iron-, manganese-, or magnesium-deficiency has been induced in Euglena gracilis. Each arrests cell proliferation, decreases the intracellular content of the deficient metal, and increases that of several other metals. Light and electron microscopy of stationary phase cells reveal that Fe-deficient (-Fe) cells are similar in size and shape to control organisms. Magnesium-deficient (-Mg) cells, however, are larger, and approximately 14% are multilobed, containing 2 to 12 lobes of equal size emanating from a central region. Individual (-Mg) cells and each lobe of multilobed cells contain a single nucleus. Manganese-deficient (-Mn) organisms are morphologically more heterogeneous than (-Fe) or (-Mg) cells. Most are spherical and larger than controls. Approximately 15% are multilobed but, unlike (-Mg) cells, contain lobes of unequal size with either zero, one, or several nuclei present in each. Nuclei of (-Mn) cells differ in size and shape from those of control, (-Fe), or (-Mg) cells. All three deficient cell types accumulate large quantities of paramylon. Other cytoplasmic structures, however, appear normal. Addition of Fe, Mn, or Mg to the respective deficient stationary phase cultures reverses growth arrest and restores normal morphology. The results suggest that Fe-, Mn-, and Mg-deficiencies affect different stages of the E. gracilis cell cycle.     

Long-Distance Dispersal of a Female Cougar in a Basin and Range Landscape

Abstract: We used Global Positioning System technology to document distance, movement path, vegetation, and elevations used by a dispersing subadult female cougar (Puma concolor) through the fragmented habitat of the Intermountain West, USA. Over the course of 1 year, female number 31 moved 357 linear km, but an actual distance of 1,341 km from the Oquirrh Mountains, Utah to the White River Plateau, Colorado, constituting the farthest dispersal yet documented for a female cougar. This cougar successfully negotiated 4 major rivers and one interstate highway while traversing portions of 3 states. Our data suggest that transient survival, and therefore total distance moved, may be enhanced when dispersal occurs during the snow-free season due to low hunting pressure and greater access to high elevation habitats. Long-distance movements by both sexes will be required for the recolonization of vacant habitats, and thus inter-state management may be warranted where state boundaries do not coincide with effective dispersal barriers.     

Comparison of properties of collected cells and cells from the culture vessel during continuous culture of Streptococcus mutans Ingbritt

In continuous-culture studies chemostat effluents are usually collected into a receiving flask in an ice bath to obtain enough cells for an experiment. It is assumed that the properties of these are not significantly different from those of the culture in the chemostat vessel. This assumption has been tested for the dental pathogen Streptococcus mutans Ingbritt. Collected supernatant fluid and cells were compared with supernatant fluid and cells taken directly from the culture vessel, for four major groups of culture properties: viability and biomcss, concentrations of metabolites and nutrients, activities of selected enzymes, and glycolytic rates. The assumption held true except for glycolytic rate during endogenous metabolism. It is suggested that comparison of collected and culture vessel cells is an important control which should be done in all continuous culture studies of microbial physiology and biochemistry, but that the properties of Strep, mutans cells collected on ice up to 16 h do reflect those of cells actively growing in the chemostat.     

Initiation of Procambial Strands in Leaf Primordia of Dactylis glomerata L. as an Example of a Temperate Herbage Grass

This study is concerned with the examination of shoots of herbagegrasses, particularly Dactylis glomerata L., for comparisonwith earlier investigations on this species and on the cerealTriticum aestivum L. The main features of procambial strandinitiation are found to be the same in all the herbage grassesexamined and to be very similar to those in Triticum. Thus,in a vegetative shoot, all the procambial strands originatein the leaf primordia independently of the vascular system ofthe older parts of the plant, and extend downwards from theirfirst point of origin. For the median strands, the first pointof origin is in the disc of insertion of the primordium, butfor later strands it is progressively higher, so that the laststrands are initiated well up in the free portion of the primordium.The course of the median and first and second lateral strands,in the first two discs of insertion that they penetrate, isvery regular and predictable. However, two discs of insertionbelow the point of initiation of strands, their course is interruptedby the strands of the primordium directly below (there is onealternating primordium between them), and from this point downwardsvariations, both specific and between individual plants andprimordia, occur. This is the region where connexion with thevascular supply of the rest of the plant is first established.The timing of the arrival of young strands from above and ofthe development of successive nodal plexi from below, via whichmost interconnexions are established, will give some variationto the early development of this region.     

Preparation and properties of Vibrio cholerae antifimbrial antibody

The presence of fimbriae on the Vibrio cholerae strains used was assessed by pellicle formation, haemagglutination activity and electron microscopy. Fimbrial suspensions were prepared by shearing them off the organisms, then separating them from other components by absorbing them on to rabbit red blood cells. Rabbits were then immunized with the fimbrial-red cell suspensions and the antibodies evoked were titrated by haemagglutination inhibition, agglutination, vibriocidal and immobilization techniques.     

The Effect of Rooting Space on Whole Plant and Leaf Growth in Brussels Sprouts (Brassica oleracea var. gemmifera)

Seedlings of Brassica oleracea var. gemmifera DC. (Brusselssprouts) were grown in four pot sizes over a 4-week period.Whole plant, stem, root and foliage d. wts and foliage area,together with specific leaf area, leaf area ratio and numberof leaves initiated were reduced by restricting rooting space.Individual leaves showed similar reductions in d. wt and area,with the effect being more pronounced in later-formed leaves.Cell counts and measurements on the epidermis and palisade mesophylllayers of the first four leaves showed that the reduction ingrowth was due to reduced cell division. Cell numbers in thefirst-formed leaf were halved over the range of pot sizes used,and there was a progressively greater reduction in cell numbersin later-formed leaves. There was some tendency for cell sizeto decrease with decreasing rooting space, but this was notgeneral and was most marked between plants grown in the twosmallest pot sizes. Brassica oleracea var. gemmifera, Brussels sprouts, rooting space, growth analysis, leaf growth, cell numbers, cell sizes     

The brain of Echiniscus viridissimus Peterfi, 1956 (Heterotardigrada): a key to understanding the phylogenetic position of tardigrades and the evolution of the arthropod head

The brain of Echiniscus viridissimus , Peterfi, 1956 is composed of a series of orthogonally arranged neuropils. The most anterior neuropils are rireumbuccal, positioned dorso-and ventrolateral to the buccal tube and are associated with ganglia for sensory receptors of the mouth cone. Posterior to these are neuropils and ganglia for the (1) internal cirri and (2) cephalic papillae, external cirri, cirri A and clavae. They are joined by two pairs of vertical tracts to neuropils lateral to the buccal tube. A model based on the postcephalic organization of the tardigrade nervous system is used to propose a transformation of segmental ganglia that gives an arrangement congruent with the pattern of neuropils in the brain. The analysis suggests that the brain is derived from nervous elements of four segments with the fourth segment having contributed paired dorsal ganglia and their connecting vertical tracts to the first trunk ganglia of the ventral chain. The organization of the head of tardigrades is compared with that of other lobopods and arthropods and several possible key evolutionary innovations are offered. In addition homologous characters for the heads of tardigrades and other lobopods and arthropods are proposed and the nomenclature for the tardigrade cephalic nervous system is discussed.