Extended interactions with prothrombinase enforce affinity and specificity for its macromolecular substrate.

The specific action of serine proteinases on protein substrates is a hallmark of blood coagulation and numerous other physiological processes. Enzymic recognition of substrate sequences preceding the scissile bond is considered to contribute dominantly to specificity and function. We have investigated the contribution of active site docking by unique substrate residues preceding the scissile bond to the function of prothrombinase. Mutagenesis of the authentic P(1)-P(3) sequence in prethrombin 2/fragment 1.2 yielded substrate variants that could be converted to thrombin by prothrombinase. Proteolytic activation was also observed with a substrate variant containing the P(1)-P(3) sequence found in a coagulation zymogen not known to be activated by prothrombinase. Lower rates of activation of the variants derived from a decrease in maximum catalytic rate but not in substrate affinity. Replacement of the P(1) residue with Gln yielded an uncleavable derivative that retained the affinity of the wild type substrate for prothrombinase but did not engage the active site of the enzyme. Thus, active site docking of the substrate contributes to catalytic efficiency, but it is does not determine substrate affinity nor does it fully explain the specificity of prothrombinase. Therefore, extended interactions between prothrombinase and substrate regions removed from the cleavage site drive substrate affinity and enforce the substrate specificity of this enzyme complex

Total phosphorus content of Neomysis integer

Measurements of total phosphorus in Neomysis integer, showed an inverse relationship between the total phosphorus content and body weight (wet). Immature forms, presented higher content of phosphorus. Some possible implications of these results are discussed.Determinação de fósforo total em Neomysis integer demonstrou uma relação inversa entre quantidade de fósforo em µg e peso úmido de animal. Formas imaturas apresentaram maior quantidade de fósforos que machos e fêmeas. Algumas implicações possíveis são discutidas

Analysis of curtailment at The Geysers geothermal Field, California

Geothermal energy has traditionally been viewed as a baseload energy source, but the rapid growth of intermittent renewable energy has led to a need for more flexibility in power generation to avoid mandatory curtailment imposed by grid operators. This study of curtailment at The Geysers provides insights into the magnitude, duration, frequency, temporal and spatial distribution, and potential causes of curtailment events between 2013 and 2018. Annual levels of curtailment range during this period from 9 to 47 GW h, representing 0.15 to 0.81 % of the net generation. Most curtailments occurred at the power plants connected to a lower capacity transmission line and may result from transmission constriction. There is a clear link between negative pricing and economic curtailment, especially when solar production is higher. Economic curtailment events tend to be only a few hours and vary in magnitude up to almost 300 MW, whereas transmission-related curtailment events can be up to several weeks in duration. It is likely that curtailment of geothermal power will be an increasing concern, and could be mitigated by flexible generation strategies and increases in energy storage. It is critical to know the nature of curtailment events so that flexible generation options can be assessed properly

Phenology of the Genus Crotalaria L. (Fabaceae-Papilionoideae) of Holalkere, Hosadurga and Chitradurga Thaluks of Chitradurga District, Karnataka, India

The present study describes detailed distribution of the genus Crotalaria L. in a natural habitat. This research is carried out by extensive field survey and observation across all the 3 thaluks of Chitradurga, area is botanized for Crotalaria species in all seasons and critically analysed the phenological features of all the documented species during the study period 2018-2021. We have recorded 11 species of Crotalaria, Crotalaria calycina Schrank., Crotalaria globosa Wight & Arn, Crotalaria goreensis Guill. & Perr., Crotalaria hebecarpa (DC.) Rudd. Crotalaria juncea L., Crotalaria orixensis Willd., Crotalaria pallida Aiton., Crotalaria prostrata Willd., Crotalaria pusilla DC., Crotalaria retusa L., and Crotalaria varicosa Polhill. Data obtained through this research is the basis for the study of further characterisation of Crotalaria species; this research describes the importance of phenology in taxonomy and the behaviour biology of the Crotalaria species, as they are economically important group

Factors influencing the local scale colonisation and change in density of a widespread invasive plant species, Lantana camara, in South India

Identifying factors that underlie invasive species colonisation and change in density could provide valuable insights into the mechanisms of biological invasions and for invasive species management. We examined a suite of factors potentially influencing the landscape-level invasion of Lantana camara L., one of the most ubiquitous invasive species in South Asia. These factors included disturbance factors like forest fires, historical habitat modification, and edge effects, in addition to factors like propagule pressure and habitat suitability. We examined the relative importance of these factors on the colonisation and change in density of L. camara in the Biligiri Rangaswamy Temple Tiger Reserve, Western Ghats, India. We used extensive (1997–2008) datasets tracking the presence and abundance of L. camara and combined these with corresponding data on disturbances, propagule pressure, and habitat suitability. We used an information-theoretic model selection approach to determine the relative importance of each factor on the colonisation and change in density of L. camara. Colonisation was mainly a function of proximity to already established populations (i.e. propagule pressure), whereas increase in L. camara density appeared to be constrained by high fire frequency. Research and management efforts need to recognize the multi dimensional nature of mechanisms underlying L. camara’s success during different invasion phases when strategizing interventions to mitigate its effects