Isolation ofThiothrix in pure culture and observation of a filamentous epiphyte onThiothrix

Thiothrix was isolated from two sites, one in Arizona and the other in Florida, although the former strain was subsequently lost. This is the first report of the isolation ofThiothrix in pure culture. The cells in aThiothrix bloom found in a stock tank had filamentous “appendages”, which proved to consist of a segmented, trichomatous, epiphytic bacterium.     

Cardiovascular Response to Interpersonal Provocation and Mental Arithmetic among High and Low Hostile Young Adult Males

To examine the relation between hostility and cardiovascular reactivity to stress, 42 undergraduate men were categorized into high and low hostile groups based on responses to the Cook Medley Hostility Scale. Participants engaged in two laboratory tasks: a Cognitive Task (mental arithmetic) and a Social Task (confrontation role-play). Cardiovascular measures of heart rate and blood pressure were obtained throughout rest and task periods and participants provided ratings of state anger and forgiveness following task completion. Results revealed that low hostile participants exhibited greater systolic blood pressure (SBP) responses to both tasks than high hostile participants (p < .05), but no significant group differences were observed for heart rate or diastolic blood pressure. High hostile men reported greater state anger during resting conditions and less forgiveness following completion of tasks than low-hostile counterparts, but neither of these findings moderated the relation between hostility and SBP reactivity. Higher ratings of forgiveness were associated with lower SBP reactivity. These findings show that hostility is not always associated with exaggerated cardiovascular reactivity to stress, and the influence of various moderating factors should be considered in elucidating this relation.     

Hybrid watermilfoil (Myriophyllum spicatum × Myriophyllum sibiricum) exhibits traits associated with greater invasiveness than its introduced and native parental taxa

Hybridization has been associated with increased invasiveness in plants. In North America, the hybrid aquatic plant Myriophyllum spicatum?×?Myriophyllum sibiricum (hybrid watermilfoil, hereafter HWM) is a cross between non-native invasive Eurasian watermilfoil (M. spicatum, EWM) and native northern watermilfoil (M. sibiricum, NWM). Lab-based trials have demonstrated higher growth rates in HWM compared to EWM and NWM, but these patterns have not been systematically examined in the field. In this study, we compared the invasiveness of HWM to its parental taxa, EWM and NWM, by examining the amount and timing of: (1) flowering, (2) surface cover, and (3) biomass (using stem counts as a proxy). We conducted repeat surveys of Myriophyllum beds at eight lakes (2–3 lakes/taxon) in the Minneapolis–St. Paul Metropolitan area (Minnesota, USA) between June 2017 and November 2018. HWM produced more flower spikes earlier and overall, and maintained consistently more flower spikes throughout the growing season than EWM and NWM. In addition, surface cover reached greater annual peaks and was higher for longer throughout the growing season for HWM than for both parental taxa. We did not observe a significant difference in stem counts among the three taxa, but HWM did reach a higher maximum number of stems than either parental taxon. This study provides field-based evidence of increased invasiveness associated with hybridization between EWM and NWM; specifically, greater reproductive potential via flowering and greater surface cover may increase HWM spread, have greater impacts on native species, and pose more of a nuisance to lake users.

     

Viral heat resistance and infectious ribonucleic acid.

High-titer suspensions of poliovirus 1 and coxsackievirus B-2 were shown to contain a heat-resistant fraction when heated for 65 min at temperature ranging from 56 to 70 degrees C. The addition of ribonuclease to the heated suspensions eliminated plaque production in the cell cultures, indicating that the resistant fraction was infectious ribonucleic acid that had been liberated from ruptured viruses during the heating process.     

A convenient set of vectors for expression of multiple gene combinations in plants

A set of vectors has been developed that simplify shuttling expression cassettes between small plasmids of high copy number ideal for experiments involving biolistic transient expression and a binary transformation plasmid. Three cassettes for the expression of a cloned coding sequence behind different promoters have been modified; combinations of these cassettes can be excised withNot I, and sequentially cloned into the transformation vector in a procedure that removes the first cloning site. The system is demonstrated by inducing anthocyanin synthesis with paired regulatory genes of maize biolistically delivered to a maize cell suspension, and then expressed in transformed tobacco.