Leaf anatomy of Caltha dioneaefolia Hooker (Ranunculaceae) – is this species carnivorous?

The leaf of C. dioneaefolia is composed of two pairs of lobes, each pair resembling a trap of the carnivorous plant Dionaea. The anatomy of the leaf was studied to examine the possibility that this species, like Dionaea , is carnivorous. Neither glandular structures, nor trigger hairs could be found, and it was concluded that C. dioneaefolia is non-carnivorous. The leaf of C. dioneaefolia is dorsiventral. The inner surface of each leaf lobe is covered with a thick cuticle with numerous anomocytic stomata. The stomata seem to be functional, not occluded. The outer surface of each leaf lobe is covered with a thin cuticle and has no stomata. The mesophyll is of the conjugate type, with papillae both in the pallisade and in the spongy mesophyll cells. The conductive system is developed to only a limited extent.     

Isolation and Characterization of Chlamydomonas reinhardtii Mutants with Defects in the Induction of Flagellar Protein Synthesis after Deflagellation1,2

Amputating the flagella of Chlamydomonas reinhardtii stimulates increased synthesis of many flagellar proteins within 30 min. We have isolated a series of mutants which are defective in this stimulation, taking advantage of the fact that cells which cannot stimulate flagellar protein synthesis cannot regenerate flagella. More than a dozen mutants which have flagella, but cannot regenerate them after amputation, were isolated and studied by in vivo labeling to identify those non-regenerator mutants which were specifically defective in the induction of flagellar protein synthesis. Ten such mutants have been identified, and in each of them flagellar amputation does not stimulate the synthesis of any of the major flagellar proteins. At least four of the mutants display an interesting conditional phenotype. The synthesis of flagellar proteins after deflagellation is defective only in gametic cells; vegetative cells of these mutants are capable of flagellar protein synthesis after flagellar amputation.     

The impact on native mammals of land-use changes and exotic species in the Bega district,New South Wales,since settlement

Historical records for the Bega district were examined to chart the environmental changes wrought by Europeans through habitat alteration and the introduction of exotic species, and to interpret the impact of these on native mammals. Early recorded increases in native mammal populations, particularly koalas, may have been attributable to a decline in Aboriginal hunting pressure. After settlement in 1830, the valley forest was cleared progressively, ecosystems were altered by grazing and improved pastures, and many introduced plants became weeds in the disturbed environment. The timber industry exploited the forests of the valley and then the slopes of the surrounding mountains. Three exotic mammal species had a major impact on the district — hares, rabbits and foxes. Of the native fauna, the large and medium sized mammal species were those recorded most frequently. Dramatic fluctuations in numbers occurred in most of these species, and many reached plague proportions between 1880 and 1910, after which their numbers fell sharply. The peaks of exotic mammals and the decline of native mammals coincided with the clearing of the remaining forests in the Bega Valley. Many native mammal species are now rare, four are in danger of extinction, and at least six species have become locally extinct since settlement. As most of the native mammal populations in the district now occur in the State Forests surrounding the Bega Valley, the importance of preserving or managing these forests for wildlife must be weighed against proposals to manage the forests for pulpwood (woodchip) production.     

Inhibition of Somatic Embryogenesis in Tissue 2Medicago sativa by Aminoethoxyvinylglycine, Amino-oxyacetic acid, 2, 4-Dinitrophenol and Salicylic Acid at Concentrations which do not Inhibit Ethylene Biosynthesis and Growth

Meijer, E. G. M. and Brown, D. C. W. 1988. Inhibition of somaticembryogenesis in tissue cultures of Medicago sativa by aminoethoxyvinylglycine,amino-oxyacetic acid, 2, 4-dinitrophenol and salicylic acidat concentrations which do not inhibit ethylene biosynthesisand growth. J. exp. Bot. 39: 263–270. The effects of aminoethoxyvinyglycine (AVG), amino-oxyaceticacid (AOA), 2, 4-dinitrophenol (DNP) and salicylic acid (SA)on ethylene production, tissue proliferation and somatic embryo-genesisin a recently developed rapid in vitro regeneration system ofMedicago sativa L. were examined. Contrary to numerous publications,AVG, AOA and DNP did not affect the rate of ethylene biosynthesis,while SA even caused an increase in ethylene production. Allfour compounds were, however, potent inhibitors of somatic embryoformation in the M. sativa tissue cultures, even at concentrationswhich did not affect tissue growth. Generally, a 5-d exposureto the inhibitors reduced the number and quality of somaticembryos obtained. It is suggested that the inhibitors may notreach the site of action of enzymes involved in ethylene biosynthesisand may possibly block other biosynthetic pathways which areof crucial importance to somatic embryo development. The resultsindicate that a delicate differentiation process like somaticembryogenesis is very sensitive to metabolic perturbances. Theresults are also discussed in the light of other known effectsof these four compounds on higher plants. Key words: Ethylene, Medicago sativa, somatic embryogenesis, tissue culture     

EFFECT of OXYRASE ON GROWTH of SALMONELLA spp. and LISTERIA MONOCYTOGENES IN the "UNIVERSAL PREENRICHMENT MEDIUM"

The importance of Salmonella and Listeria monocytogenes in food safety is well-known. Recovery of these organisms is usually done in different types of enrichment broths. Recently Bailey and Cox (1992) reported the development of a "Universal Preenrichment Medium" capable of recovering both Salmonella and Listeria monocytogenes , thus eliminating the need of using two broths to enrich these important foodborne pathogens. In our laboratory we have ascertained that Oxyrase, an oxygen scavenger, is able to allow the rapid growth of Listeria monocytogenes and other Listeria spp. (Yu and Fung 1991a) as well as other facultative anaerobic foodborne pathogens (Yu and Fung 1991b). It seems reasonable that Oxyrase will be able to stimulate growth of Salmonella spp. and Listeria monocytogenes in the "Universal Preenrichment Medium." the purpose of this investigation was to ascertain the stimulatory capability of Oxyrase on Salmonella spp. and Listeria monocytogenes in the "Universal Preenrichment Medium."     

DETECTION of ENTEROTOXIGENIC CLOSTRIDIUM PERFRINGENS IN GROUND BEEF

Clostridium perfringens is widely distributed in foods. This experiment was performed to assess occurrence of C. perfringens cultures and toxigenic strains isolated from ground beef Samples (118) were collected from 20 locations in Northeast Kansas and the number of C. perfringens was enumerated in these samples by Fung's Double-tube method with tryptose sulfite cycloserine agar medium. Out of 118 samples, 54 (46%) were found positive for C. perfringens. Pure isolates of C. perfringens were further grown in cooked meat medium for 24 h at 42C then heat shocked at 75C for 20 min and inoculated into modified Duncan and Strong medium for production of C. perfringens enterotoxin. Presence of enterotoxin was tested by the reverse passive latex agglutination test (Oxoid), which can detect enterotoxin up to a minimum level of 2 ng/mL. the data indicate that 46% of the beef samples harbored C. perfringens , but only 32 (6%) of 525 isolates were found to produce enterotoxin. This study emphasized the importance of continued surveillance of C. perfringens in meats and meat products and assessment of the toxigenesis of isolates.     

Nocturnal Accumulation of Acid in Leaves of Wall Pennywort (Umbilicus rupestris) Following Exposure to Water Stress

Physiological responses to water stress (drought) have beeninvestigated in Umbilicus rupestris (wall pennywort) by comparingcontrol (well-watered) and draughted plants with respect to(i) diurnal fluctuations in the acid content of the leaves,(ii) CO₂ exchange patterns and (iii) stomatal conductance. Controlplants show no diurnal fluctuations in acid content, whereasafter 6 d of drought a clear CAM-type pattern (nocturnal acidificationfollowed by deacidification in the light) is observed. In controlplants, the CO₂ exchange pattern over a 24 h period is of atypical C-3 ‘square-wave’ type, with extensive CO₂uptake in the light and CO₂ output in the dark. In droughtedplants the day-time CO₂ uptake is confined to a morning ‘burst’,whilst night-time CO₂ output is markedly reduced. There is howeverno net noctural uptake of CO₂. In control plants, stomatal conductanceis high during the day (especially in the first half of theday) falling to a low level at the onset of darkness, and thenrising slowly through the remainder of the night. In droughtedplants, stomatal conductance is very low, except that thereis morning ‘burst’ of high conductance and a periodduring the night when conductance is higher than in controlplants. These results are discussed in relation to the response of U.rupestris to drought both in laboratory and in field conditions. Umbilicus rupestris, wall pennywort, CO₂ exchange, Crassulacean acid metabolism, drought, stomatal conductance, water stress     

Proceedings of the signature series symposium “cellular therapies for orthopaedics and musculoskeletal disease proven and unproven therapies—promise,facts and fantasy,” international society for cellular therapies,montreal, canada,may 2, 2018

The Signature Series Symposium “Cellular Therapies for Orthopaedics and Musculoskeletal Disease Proven and Unproven Therapies—Promise, Facts and Fantasy” was held as a pre-meeting of the 26^th International Society for Cellular Therapy (ISCT) annual congress in Montreal, Canada, May 2, 2018. This was the first ISCT program that was entirely dedicated to the advancement of cell-based therapies for musculoskeletal diseases. Cellular therapies in musculoskeletal medicine are a source of great promise and opportunity. They are also the source of public controversy, confusion and misinformation. Patients, clinicians, scientists, industry and government share a commitment to clear communication and responsible development of the field. Therefore, this symposium convened thought leaders from around the world in a forum designed to catalyze communication and collaboration to bring the greatest possible innovation and value to patients with musculoskeletal conditions.     

Circular rDNA Replicons Persist in Tetrahymena thermophila Transformants Synthesizing GGGGTC Telomeric Repeats

Site-directed mutagenesis of the telomerase RNA from Tetrahymena thermophila was used previously to demonstrate the templating function of a sequence within this RNA; this sequence specifies the sequence of telomeric DNA in vivo. The possible functional importance of a phylogenetically conserved nucleotide outside the telomerase RNA template region was investigated by a similar experimental approach. The telomerase RNA gene was altered by site-directed mutagenesis, cloned in a circular selectable transformation vector consisting of an rRNA gene carrying a selectable drug resistance marker, and introduced into macronuclei of vegetatively dividing Tetrahymena thermophila by microinjection. Changing an invariant A to U at position 16 of the telomerase RNA (A16U) had no effect detectable by phenotype on telomerase function in vivo. However these experiments showed that a telomerase template alteration that dictates the synthesis of the mutant telomeric DNA sequence GGGGTC leads to a profound change in the population of rDNA replicons. The addition of GGGGTC mutant repeats leads to selective pressure for the loss of high copy linear rDNA, and the rRNA genes are maintained in the form of the circular rDNA replicons introduced during transformation.     

Effects of algal food quality on fecundity and population growth rates of Daphnia

1. Food quality was at least as important as food quantity for both fecundity and population growth responses of the cladoceran Daphnia pulicaria fed the green alga Ankistrodesmus falcatus grown under N limitation, P limitation, or non-limited condition.
2. The fecundity of D. pulicaria was reduced under conditions of low food quality (low N or low P) compared with that for animals fed control non-limited algae regardless of ration size. The reduced fecundity of D. pulicaria fed P-limited food could be partially alleviated by increasing the ration (hence, compensation), but such was not the case for animals fed N-limited food.
3. Population growth rates of D. pulicaria ( r _max) were significantly reduced under conditions of low-quality food for both N-limited and P-limited algae. Population growth rates were unaffected by ration size, indicating no compensation.