The life cycles of Ocfotiara russelli and Sfomofoca atra (Cnidaria, Anthomedusae, Pandeidae)

The previously unknown life cycles of Ocioiiara russelli and Stomoroca alru are described. Both species present differentiated hydroids and medusae. From the morphology of the newly liberated medusae both species are referred to the Pandeidae and, from the presence of a manubrial peduncle, to the subfamily Stomotocinae. together with Timoides . Some aspects of feeding and gonad growth are described and discussed.     

Comparative anatomy and systematics of Senghas's cushion species of Maxillaria (Orchidaceae)

Using data obtained through anatomy and morphology, we used cladistics to examine the monophyly of Senghas's proposed classification of Maxillaria cushion plants and his placement of Mormolyca ringens. Trignidium obtusum was chosen as the outgroup. Leaves have multicellular hairs sunken in crypts, primarily anomocytic or primarily tetracytic stomatal apparatuses, homogeneous mesophyll, and scattered fibre bundles. Three types of adaxial hypodermis were observed: (1) water-storage cells, (2) fibre bundles scattered among water-storage cells, and (3) fibre bundles scattered among chlorenchymatous cells. Abaxial hypodermis of fibre bundles occurs in several Maxillaria species and in Trigonidium obtusum. At the midvein of the leaf, adaxial mesophyll cells of most species are anticlinally extended and empty, and the abaxial mesophyll is usually collenchymatous. Vascular bundles are collateral and usually in a single series. Pseudobulb epidermal cell walls are thin, or outer walls are thickened. Ground tissue consists of water-storage and assimilatory cells with vascular bundles and associated lacunae scattered throughout. Roots are velamentous and exodermal cell walls are usually n-thickened with tenuous bands of scalarifom thickenings on longitudinal walls. Tilosomes may be plaited, baculate, or spongy. Endodermal cell walls are usually U-thickened and pericycle cell walls are usually O-thickened opposite phloem sectors. Stegmata line the periphery of the thickened pericycle cells opposite phloem sectors in M. picta. Pith may be parenchymatous or sclerenchymatous. According to our phylogenetic analysis, Mormolyca ringens is consistently nested within the cladistic structure of Maxillaria. Therefore, Maxillaria likely is paraphyletic if Mormolyca ringens is recognized as generically distinct. It appears that Senghas's subgroup divisions of the unifoliate pseudobulbous maxillarias may also be artificial.     

Plasmodium falciparum: Increased and Multiple Invasion During Short Periods of Time

We describe how to obtain an increased merozoite invasion of Plasmodium falciparum into human erythrocytes during short periods of time. Using this procedure, infected erythrocytes show multiple invasions (2–4 merozoites per erythrocyte), amplifying, several times, the effects of parasite entry into host cells. The procedure yields synchronous cultures (2-h age range) with parasitemia as high as 15%. It is possible to reach parasitemia of 50% or higher allowing for a 6-h invasion period.     

Reconstruction of Laser-scanned 3D Torso Topography and Stereoradiographical Spine and Rib-cage Geometry in Scoliosis

Assessments of scoliosis are routinely done by means of clinical examination and full spinal x-rays. Multiple exposure to ionization radiation, however, can be hazardous to the child and is costly. Here, we explain the use of a noninvasive imaging technique, based on laser optical scanning, for quantifying the three-dimensional (3D) trunk surface topography that can be used to estimate parameters of 3D deformity of the spine. The laser optical scanning system consisted of four BIRIS laser cameras mounted on a ring moving along a vertical axis, producing a topographical mapping of the entire torso. In conjunction with the laser scans, an accurate 3D reconstruction of the spine and rib cage were developed from the digitized x-ray images. Results from 14 scoliotic patients are reported. The digitized surfaces provided the foundation data to start studying concordance of trunk surface asymmetry and spinal shape in idiopathic scoliosis.     

Learning in Spiders

After the spider, Zygiella x-notata Cl. has been enticed toleave the retreat and catch a fly in a web turned upside-down,it takes a relatively long time to return to the retreat. Thereturn-time is divided into periods of active searching andmotionlessness. Several factors have been found to shorten significantlythe searching and motionless time; among them are youth of theanimals, small number of webs previously built, the positionof the web before and between experiments, and repetition oftrials at certain time intervals. The observed phenomenon andvariations in time are explained in terms of current conceptsof memory function and information processing.     

Lymphoreticular Neoplasia and Immunity in Amphibia

SYNOPSIS. This report deals with observations which suggestnew insights and speculations with regard to the unique developmentalcycle of lymphoreticular neoplasia in adult Xenopus laevis andthe systemic controls which may be imposed upon it. Evidenceis presented which suggests that: (1) Organismally imposed necrosisof visceral tumor foci was effectively suppressed by subsequentimplantation of allo-tumor foci but not by normal tissue allo-grafts;(2) Recovery of the healthy state of neoplastic foci followingnecrosis appears to depend on the acquisition of new tumor cellsrather than on cloning by survivors of necrosis in primary foci;(3) Diseased organisms eventually develop controls which suppressthe growth of implanted allotumor foci (tumor growth suppressionwas also demonstrated with splenic but not liver fragments fromatoad which survived a prior challenge with a homogenate of neoplastictissue); (4) Animals with this lympho-proliferative disorderappear to have an immunologic deficiency for cell-mediated responses;(5) Normal young adult Xenopus hosts generate a chronic ratherthan acute allograft response. This information may be of interestin considering the phylogeny of both the cell-mediated responseand the type of surveillance mechanism utilized as a defenseagainst neoplasia     

Etude au Microscope Electronique du CiliéPseudomicrothorax dubius Maupas

SYNOPSIS. Ciliates of the genus Pseudomicrothorax present, at the ultrastructural level, some remarkable peculiarities from the points of view of both cytology and taxonomy. The trichocysts have 4 apical blades which are characteristic of the family Microthoracidae; the curious subcuticular membrane is found in the Microthoracidae and, admittedly less typically, in the Nassulidae; the cytopharyngeal armature is exactly comparable to that of the Nassulidae. These facts, like those of Thompson and Corliss on the organization of the oral ciliates, show—as suggested by Corliss–that the taxonomic position of the genus Pseudomicrothorax throws light on certain stages of the evolution of the Ciliata.     

CONVERGENT SHELL MORPHOLOGY IN INTERTIDAL GASTROPODS

The functional morphology of shell infrastructure in 2 speciesof intertidal trochid was compared with that in 2 species ofnerite. The shell of Monodonta constrictais typical of the majorityof trochids. The shell is composed of 4 layers: a distal layer(calcite), anouter prismatic layer (aragonite), a nacreous layer(aragonite), and an oblique prismatic layer (aragonite). Monodontalabio lacks a distal layer and an oblique prismatic layer. Theoblique prismatic layer is replaced by an inner prismatic layerwhich forms an apertural ridge as a result of deposition andresorption. The shells of Nerita versicolor and N. tessellataconsistof 3 layers: an outer prismatic layer (calcite), a crossedlamellar layer (aragonite), and a complex crossed lamellar layer(aragonite). The complex crossed lamellar layer is covered withinclined platelets which superficially resemble the surfaceof the ique prismatic layer of trochids. In addition, the complexcrossed lamellar layer forms an apertural ridge which is similarin appearance to that of Monodonta labio. The outer surfaceof the mantle of Nerita versicolor and N. tessellata is throwninto a series of large folds which lie in contact with the inclinedplatelets of the omplex crossed lamellar layer. The interactionof the mantle folds with the inclined platelets is thought toserve as a rachet mechanism to aid in extension of themantle;a similar function has previously been proposed for trochids.The apertural ridges of Monodonta labio and Nerita are thoughtto prevent excessive desiccation when these gastropodsare exposedat low tide. ¹Contribution No. 56 of the Tallahassee, Sopchoppy & GulfCoast Marine Biological Association (Received 6 July 1979;     

Characterization of eight microsatellite loci in Steller sea lions (Eumetopias jubatus)

Steller sea lions (Eumetopias jubatus) are listed as an endangered species in western Alaska and have exhibited a significant population decline throughout their range. Eight microsatellite loci were isolated from genomic DNA libraries. In addition, all these markers were found to be variable in nine individuals of the California sea lion (Zalophus californicus). This panel of markers was developed to analyse population structure in Steller sea lions throughout their range.