Phylogenetic analysis of the Rhabdocoela (Platyhelminthes) with emphasis on the Neodermata and relatives

Phylogenetic systematic analysis of 24 taxa representing the rhabdocoel platyhelminths, based on a suite of 89 morphological characters, produced two equally parsimonious trees, 181 steps long, with a consistency index (CI) of 0.69 and a rescaled consistency index (RCI) of 0.56, differing only with respect to that portion of the tree containing Umagillidae, Acholadidae, Graffillinae, Pseudograffillinae, Pterastericolidae and Hypoblepharinidae. Our results accommodate all previously proposed sister taxa to the Neodermata in a single clade in which ((Dalyelliidae + Temnocephalida) Typhloplanidae) is the sister group of ((Fecampiidae +  Urastoma ) ( Udonella ((Aspidogastrea + Digenea) (Monogenea (Gyrocotylidea (Amphilinidea + Eucestoda)))))). Bootstrap and jackknife analyses indicate that the groupings of ((Dalyelliidae + Temnocephalida) Typhloplanidae) and of ((Fecampiidae +  Urastoma ) ( Udonella ((Aspidogastrea + Digenea) (Monogenea (Gyrocotylidea (Amphilinidea + Eucestoda)))))) are highly robust, with the latter clade having a CI of 90% and RCI of 82%. Disagreements among previous analyses of these taxa have been due to the influence of missing data for critical characters in key taxa and differences in the taxa analysed, rather than any inherent weakness in the morphological data. Non-phylogenetic systematic approaches to homology assessment and misconceptions regarding phylogenetic systematic methodology are discussed. Recent analyses combining sequence data with a subset of approximately 60% of the morphological characters should be re-assessed using the entire morphological database. Even if Udonella is a monogenean, it is most parsimonious to suggest that the common ancestor of the Neodermata had a vertebrate–arthropod two-host life cycle.     

DEVELOPMENTAL STUDIES IN PORPHYRA (BANGIOPHYCEAE). II. CHARACTERIZATIO OF THE MAJOR LECTIN BINDING GLYCOPROTEINS IN DIFFERENTIATED REGIONS OF THE PORPHYRA PERFORATA THALLUS1

Detergent soluble extracts of differentiated regions of the Porphyra perforata J. Ag. thallus (holdfast, rhizoidal, vegetative and reproductive cells) were fractionated on sodium dodecyl sulfate polyacrylamide gels. Glycoproteins were identified by their lectin affinity. Extracts from all areas of the thallus contained glycoproteins, but the staining patterns were different for each region with each of the lectins tested: concanavalin A, Ulex europeaus agglutinin, Ricinus communis agglutinin, soybean agglutinin and peanut agglutinin. These data indicate that the morphologically distinct regions of the thallus also differ biochemically. Analysis of the lectin blots revealed the presence of tissue-specific glycoproteins in the five thallus areas. Such unique glycoproteins could be used as markers of differentiation in this species.     

Serologic evidence of a Rickettsia akari-like infection among wild-caught rodents in Orange County and humans in Los Angeles County, California.

We detected antibodies reactive with Rickettsia akari, the etiologic agent of rickettsialpox in humans and in 83 of 359 (23%) rodents belonging to several species, collected in Orange County, CA. Reciprocal antibody titers >1:16 to R. akari were detected in native mice and rats (Peromyscus maniculatus, P. eremicus, and Neotoma fuscipes) and in Old World mice and rats (Mus musculus, Rattus rattus, and R. norvegicus), representing the first time that antibodies reactive with this agent have been detected in four of these species and the first report of these antibodies in rodents and humans west of the Mississippi River. We then tested serum samples from individuals who used a free clinic in downtown Los Angeles and found that 25 of 299 (8%) of these individuals had antibody titers >1:64 to R. akari. Serologic evidence suggested that R. akari or a closely related rickettsia is prevalent among several rodent species at these localities and that infection spills over into certain segments of the human population. Isolation or molecular confirmation of the agent is needed to conclusively state that R. akari is the etiologic agent infecting these rodents.     

The effects of lipoxygenase metabolites of arachidonic acid on human myometrial contractility

The effects of the lipoxygenase products of arachidonic acid, 5- and 12-hydroxyeicosatetraenoic acid (5- and 12-HETE) and leukotriene B4 (LTB4), on the spontaneous contractility of lower uterine segment human myometrial strips obtained prior to labour have been studied in vitro. 5-HETE gave a dose- dependent (10-500ng) increase in both the rate of contractions and overall contractility of myometrial strips while 12-HETE and LTB4 had no effect at the same concentrations. Prostaglandin F2 alpha (50ng) contracted all myometrial strips in a similar pattern to 5-HETE but was approximately 10 times more potent. The effect of 5-HETE may be direct or perhaps indirect via interaction with the cyclo-oxygenase pathway. The findings do not disprove the contention that the onset of parturition may be characterised by a switch in arachidonic acid metabolism in intra-uterine tissues from lipoxygenase to cyclo-oxygenase products.     

Thermal adaptations in lizard muscle function

Summary This study was undertaken to investigate thermal adaptations in muscle contractile properties in closely-related lizards with different preferred body temperatures (PBT). The species examined all belong to theSphenomorphus group of Australian skinks (Scincidae: Lygosominae). Preferred body temperatures are conservative at the generic level as follows:Ctenotus, 35°C;Sphenomorphus, 30°C;Eremiascincus, 25°C. Contractile properties of the fast glycolytic portion of the iliofibularis muscle were measured. Translational adaptations are evident in several isometric factors, including tetanic tension (Po), twitch tension (Pt), twitch time to peak tension (TPT), and twitch half-relaxation time (1/2 RT). Capacity adaptations are not evident in rates of tetanic tension development (dPo/dt) or in maximal velocities of isotonic shortening (V _max). Rotational adaptations are not evident in any contractile properties. Thermal limits on upper response temperatures are about 5°C warmer inCtenotus than in the more cryophilic species, indicative of resistance adaptation in muscle performance. Despite these adaptive shifts, there is little indication that muscle functional capacities are optimized or equalized at PBT in these lizards.Abbreviations FG fast glycolytic - IF iliofibularis muscle - PBT preferred body temperature - Po tetanic tension - Pt twitch tension - 1/2RT twitch half relaxation time - TPT twitch time to peak tension     

Transport Properties of the Tomato Fruit Tonoplast : I. Identification and Characterization of an Anion-Sensitive H-ATPase

An anion-sensitive H⁺-translocating ATPase was identified in membrane vesicles isolated from mature green tomato (Lycopersicon esculentum) fruit. The H⁺-ATPase was associated with a low density membrane population having a peak density of 1.11 grams per cubic centimeter, and its activity was inhibited by NO₃⁻, N,N′-dicyclohexylcarbodiimide and diethylstilbestrol but not by vanadate, azide, molybdate, or oligomycin. This H⁺-ATPase has an unusual pH dependence indicating both a slightly acidic and a near neutral peak of activity. Chloride was found to be a potent stimulator of ATPase activity. The K_m for the H⁺-ATPase was approximately 0.8 millimolar ATP. The characteristics of this H⁺-ATPase are very similar to those described for a number of plant cell tonoplast H⁺-ATPases suggesting that the activity identified in tomato fruit membranes is tonoplast-associated. This report demonstrates the feasibility of isolating tonoplast vesicles from acidic fruit tissues for studies of transport activities associated with fruit development and maturation.     

The effect of the crossability loci Kr1 and Kr2 on fertilization frequency in hexaploid wheat x maize crosses

Summary Dominant alleles of the Kr1 and Kr2 genes reduce the crossability of hexaploid wheat with many alien species, including rye and Hordeum bulbosum, with Kr1 having the greater effect. However, a cytological study of wheat ovaries fixed 48 h after pollination showed that the wheat genotypes Highbury (kr1, Kr2) and Chinese Spring (Hope 5B) (kr1, kr2) were crossable with Seneca 60 maize, fertilization occurring in 14.4 and 30.7% of embryo sacs respectively. The latter figure was similar to the 29.7% fertilization found in Chinese Spring (kr1, kr2). Most embryo sacs in which fertilization occurred contained an embryo but lacked an endosperm and where an endosperm was formed it was usually highly aberrant. All three wheat x maize combinations were karyotypically unstable and rapidly eliminated maize chromosomes to produce haploid wheat embryos.     

Structure of the platelet membrane glycoprotein IIb. Homology to the alpha subunits of the vitronectin and fibronectin membrane receptors

The platelet membrane glycoprotein IIb X IIIa heterodimer complex (GPIIb X IIIa) is the platelet receptor for adhesive proteins, containing binding sites for fibrinogen, von Willebrand factor, and fibronectin on activated platelets. GPIIb X IIIa also appears to be a member of a family of membrane adhesive protein receptors that plays a major role in cell-cell and cell-matrix interactions. GPIb is the larger component of this platelet receptor and is composed of two disulfide-linked subunits. In this report we describe the analysis of cDNA clones for human GPIIb that were isolated from a lambda gt11 expression library prepared using RNA from HEL cells. A total of 3.3 kilobases of cDNA was sequence, revealing a continuous open reading frame encoding both GPIIb subunits. The cDNA encodes 1039 amino acids: 137 constituting the smaller subunit, 871 constituting the larger subunit, and 30 constituting an NH2-terminal signal peptide. No homology was found between the larger and smaller subunits. The smaller subunit contains a 26-residue hydrophobic sequence near its COOH terminus that represents a potential transmembrane domain. Four stretches of 12 amino acids present in the larger subunit are homologous to the calcium binding sites of calmodulin and troponin C. Northern blot analysis using HEL cell RNA indicated that the mature mRNA coding for GPIIb is 4.1 kilobases in size. A comparison of the GPIIb coding region with available cDNA sequences of the alpha-chains of the vitronectin and fibronectin receptors revealed 41% DNA homology and 74% and 63% amino acid homology, respectively. Our data establish the amino acid sequence for the human platelet glycoprotein IIb and provide additional evidence for the existence of a family of cellular adhesion protein receptors.     

Acquisition of antigens characteristic of adult pericentral hepatocytes by differentiating fetal hepatoblasts in vitro

Antigens specific to pericentral hepatocytes have been studied in adult mouse liver, during fetal development, and in cultured fetal hepatoblasts. Antibody reactive with glutamine synthetase stained all fetal liver cells but almost all cells lost this antigen after birth; only a single layer of pericentral cells retained it in adulthood. In contrast, monoclonal antibodies to major urinary protein (MUP) did not detect the antigen until approximately 3 wk after birth, after which time the cells within 6-10 cell diameters of the central veins were positive. Cultured fetal liver cells from embryos at 13 +/- 1 d of gestation were capable of differentiating in vitro to mimic events that would occur had the cells remained in the animal. About 10-20% of the explanted cells grew into clusters of hepatocyte-like cells, all of which stained with albumin antibodies. MUP monoclonals were reactive with one-half of the differentiated fetal hepatocytes. Glutamine synthetase was present in all hepatocytes after several days in culture and gradually decreased and remained in only occasional cells, all of which also contained the MUP antigen. These findings suggest that a sequence of gene controls characterizes expression of specific genes in developing liver, and that differentiating fetal hepatoblasts are capable of undergoing similar patterns of gene activity in culture.