scholarly journals Lag times and invasion dynamics of established and emerging weeds: insights from herbarium records of Queensland, Australia

2021 ◽  
Author(s):  
Olusegun O. Osunkoya ◽  
Claire B. Lock ◽  
Kunjithapatham Dhileepan ◽  
Joshua C. Buru
Keyword(s):  
Introduced Species ◽  
Significant Proportion ◽  
Lag Time ◽  
Linear Increase ◽  
Plant Distribution ◽  
Lag Phase ◽  
Weed Species ◽  
Historical Factors ◽  
Lag Times ◽  
Invasion Waves

AbstractHerbarium records provide comprehensive information on plant distribution, offering opportunities to construct invasion curves of introduced species, estimate their rates and patterns of expansions in novel ranges, as well as identifying lag times and hence “sleeper weeds”, if any. Lag times especially have rarely been determined for many introduced species, including weeds in the State of Queensland, Australia as the trait is thought to be unpredictable and cannot be screened for. Using herbarium records (1850–2010), we generated various invasiveness indices, and developed simple invasion and standardised proportion curves of changes in distribution with time for ~ 100 established and emerging weed species of Queensland. Four major periods (decades) of increased weed spread (spikes) were identified: 1850s, 1900–1920, 1950–1960 and 2000–2010, especially for grasses and trees/shrubs. Many weeds with spikes in spread periods did so only 1–2 decadal times, except for a few species with higher spike frequencies > 6; the majority of these spikes occurred recently (1950–1990). A significant proportion (~ 60%) of Queensland’s weeds exhibit non-linear increase in spread with time, and hence have lag phases (mean: 45.9 years; range: 12–126 years); of these lag-phase species, 39% are “sleeper” weeds with > 50 years of lag time (mainly trees/shrubs and grasses). Twelve traits of invasiveness, including lag time and species-specific/historical factors were screened, of which frequency of invasion waves, spread rates and residence time were the main drivers of weeds’ distribution. The low predictive power of lag time on weed distribution suggests that retrospective analyses offer little hope for a robust generalisation to identify weeds of tomorrow.

scholarly journals Historical and Contemporary NaCl Concentrations Affect the Duration and Distribution of Lag Times from Individual Spores of Nonproteolytic Clostridium botulinum

2007 ◽  
Vol 73 (7) ◽  
pp. 2118-2127 ◽  
Author(s):  
Martin D. Webb ◽  
Carmen Pin ◽  
Michael W. Peck ◽  
Sandra C. Stringer
Keyword(s):  
Growth Medium ◽  
Clostridium Botulinum ◽  
Lag Time ◽  
Lag Phase ◽  
Growth Media ◽  
Sporulation Medium ◽  
Mature Cell ◽  
Inhibitory Effects ◽  
Subsequent Growth ◽  
Lag Times

ABSTRACT In this study we determined the effect of NaCl concentration during sporulation (0 or 3.0% [wt/vol] added NaCl) and subsequent growth (0 or 2.0% [wt/vol] added NaCl) on the distributions of times associated with various stages of the lag phase of individual spores of nonproteolytic Clostridium botulinum strain Eklund 17B. The effects of NaCl on the probability of germination and the probability of subsequent growth were also determined. Spore populations exhibited considerable heterogeneity at all stages of lag phase for each condition tested. Germination time did not correlate strongly with the times for later stages in the lag phase, such as outgrowth and doubling time. Addition of NaCl to either the sporulation or growth media increased the mean times for, and variability of, all the measured stages of the lag phase (germination, emergence, time to one mature cell, and time to first doubling). There was a synergistic interaction between the inhibitory effects of NaCl in the sporulation medium and the inhibitory effects of NaCl in the subsequent growth medium on the total lag time and each of its stages. Addition of NaCl to either the sporulation medium or the growth medium reduced both the probability of germination and the probability of a germinated spore developing into a mature cell, but the interaction was not synergistic. Spores formed in medium with added NaCl were not better adapted to subsequent growth in suboptimal osmotic conditions than spores formed in medium with no added NaCl were. Knowledge of the distribution of lag times for individual spores and quantification of the biovariability within lag time distributions may provide insight into the underlying mechanisms and can be used to improve predictions of growth in food and to refine risk assessments.

scholarly journals The CGI121 gene from Saccharomyces cerevisiae demonstrates genetic linkage to increased lag time under enological conditions

2020 ◽  
Author(s):  
Runze Li ◽  
Rebecca C. Deed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Low Temperatures ◽  
Genetic Linkage ◽  
Lag Time ◽  
Lag Phase ◽  
Phenotypic Traits ◽  
Phase Duration ◽  
Fermentation Kinetics ◽  
Lag Times ◽  
The Impact

Abstract Background In winemaking, it is standard practice to ferment white wines at low temperatures (10–18 ºC). However, low temperatures increase the fermentation duration and risk of problem ferments, which can lead to significant costs. The length of the lag period at fermentation initiation is one parameter that is heavily impacted by low temperatures. Therefore, the identification of Saccharomyces cerevisiae genes with an impact on fermentation kinetics, such as lag time, is of interest for winemaking. Results We selected a set of 28 S. cerevisiae BY4743 single deletants based on a prior list of candidate open reading frames (ORFs) mapped to quantitative trait loci (QTLs) on chromosomes VII and XIII influencing the duration of fermentative lag time by bulk segregant analysis. Five out of 28 BY4743 deletants, Δapt1, Δcgi121, Δclb6, Δrps17a, and Δvma21, differed significantly in their fermentative lag phase duration compared to BY4743 in synthetic grape medium (SGM) at 15 ºC, over 72 h. Fermentation at 12.5 ºC for 528 h, to show a greater resolution of the lag times, identified the inability of BY4743 Δapt1 to initiate fermentation and confirmed the significantly longer lag times of the BY4743 Δcgi121, Δrps17a, and Δvma21 deletants. The three candidate ORFs were deleted in S. cerevisiae RM11-1a and S288C to perform single reciprocal hemizygosity analysis (RHA). RHA hybrids and single deletants of RM11-1a and S288C were fermented at 12.5 ºC in SGM. Lag time measurements confirmed genetic linkage of CGI121 on chromosome XIII, encoding a component of the EKC/KEOPS complex, to fermentative lag phase. Nucleotide sequences of RM11-1a and S288C CGI121 alleles differed by only one synonymous nucleotide suggesting that codon bias or positional effects might be responsible for the impact of this gene on lag phase duration. Conclusion This research demonstrates a new role of CGI121 in fermentative lag time in S. cerevisiae during fermentation and highlights the applicability of QTL analysis for investigating complex phenotypic traits in yeast, such as fermentation kinetics.

Development and Evaluation of Floating Pulsatile Drug Delivery System Using Meloxicam

2017 ◽  
Vol 7 (04) ◽  
Author(s):  
ShirishaG. Suddala ◽  
S. K. Sahoo ◽  
M. R. Yamsani
Keyword(s):  
Rheumatoid Arthritis ◽  
Drug Delivery ◽  
Drug Release ◽  
Drug Delivery System ◽  
Delivery System ◽  
Lag Time ◽  
Oral Dosage ◽  
Lag Phase ◽  
Pulsatile Drug Delivery

Objective: The objective of this research work was to develop and evaluate the floating– pulsatile drug delivery system (FPDDS) of meloxicam intended for Chrono pharmacotherapy of rheumatoid arthritis. Methods: The system consisting of drug containing core, coated with hydrophilic erodible polymer, which is responsible for a lag phase for pulsatile release, top cover buoyant layer was prepared with HPMC K4M and sodium bicarbonate, provides buoyancy to increase retention of the oral dosage form in the stomach. Meloxicam is a COX-2 inhibitor used to treat joint diseases such as osteoarthritis and rheumatoid arthritis. For rheumatoid arthritis Chrono pharmacotherapy has been recommended to ensure that the highest blood levels of the drug coincide with peak pain and stiffness. Result and discussion: The prepared tablets were characterized and found to exhibit satisfactory physico-chemical characteristics. Hence, the main objective of present work is to formulate FPDDS of meloxicam in order to achieve drug release after pre-determined lag phase. Developed formulations were evaluated for in vitro drug release studies, water uptake and erosion studies, floating behaviour and in vivo radiology studies. Results showed that a certain lag time before drug release which was due to the erosion of the hydrophilic erodible polymer. The lag time clearly depends on the type and amount of hydrophilic polymer which was applied on the inner cores. Floating time and floating lag time was controlled by quantity and composition of buoyant layer. In vivo radiology studies point out the capability of the system of longer residence time of the tablets in the gastric region and releasing the drug after a programmed lag time. Conclusion: The optimized formulation of the developed system provided a lag phase while showing the gastroretension followed by pulsatile drug release that would be beneficial for chronotherapy of rheumatoid arthritis and osteoarthritis.

scholarly journals Reciprocal hemizygosity analysis reveals that the Saccharomyces cerevisiae CGI121 gene affects lag time duration in synthetic grape must

2021 ◽  
Author(s):  
Runze Li ◽  
Rebecca C Deed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Low Temperatures ◽  
Lag Time ◽  
Lag Phase ◽  
Phenotypic Traits ◽  
Time Duration ◽  
Phase Duration ◽  
Grape Must ◽  
The Impact ◽  
Reciprocal Hemizygosity Analysis

Abstract It is standard practice to ferment white wines at low temperatures (10-18 °C). However, low temperatures increase fermentation duration and risk of problem ferments, leading to significant costs. The lag duration at fermentation initiation is heavily impacted by temperature; therefore, identification of Saccharomyces cerevisiae genes influencing fermentation kinetics is of interest for winemaking. We selected 28 S. cerevisiae BY4743 single deletants, from a prior list of open reading frames (ORFs) mapped to quantitative trait loci (QTLs) on chromosomes VII and XIII, influencing the duration of fermentative lag time. Five BY4743 deletants, Δapt1, Δcgi121, Δclb6, Δrps17a, and Δvma21, differed significantly in their fermentative lag duration compared to BY4743 in synthetic grape must (SGM) at 15 °C, over 72 h. Fermentation at 12.5 °C for 528 h confirmed the longer lag times of BY4743 Δcgi121, Δrps17a, and Δvma21. These three candidate ORFs were deleted in S. cerevisiae RM11-1a and S288C to perform single reciprocal hemizygosity analysis (RHA). RHA hybrids and single deletants of RM11-1a and S288C were fermented at 12.5 °C in SGM and lag time measurements confirmed that the S288C allele of CGI121 on chromosome XIII, encoding a component of the EKC/KEOPS complex, increased fermentative lag phase duration. Nucleotide sequences of RM11-1a and S288C CGI121 alleles differed by only one synonymous nucleotide, suggesting that intron splicing, codon bias, or positional effects might be responsible for the impact on lag phase duration. This research demonstrates a new role of CGI121 and highlights the applicability of QTL analysis for investigating complex phenotypic traits in yeast.

scholarly journals The implications of lag times between nitrate leaching losses and riverine loads for water quality policy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. W. McDowell ◽  
Z. P. Simpson ◽  
A. G. Ausseil ◽  
Z. Etheridge ◽  
R. Law
Keyword(s):  
Water Quality ◽  
Mean Transit Time ◽  
Lag Time ◽  
Practice Change ◽  
N Leaching ◽  
N Losses ◽  
Leaching Losses ◽  
Nitrate N ◽  
The Mean ◽  
Lag Times

AbstractUnderstanding the lag time between land management and impacts on riverine nitrate–nitrogen (N) loads is critical to understand when action to mitigate nitrate–N leaching losses from the soil profile may start improving water quality. These lags occur due to leaching of nitrate–N through the subsurface (soil and groundwater). Actions to mitigate nitrate–N losses have been mandated in New Zealand policy to start showing improvements in water quality within five years. We estimated annual rates of nitrate–N leaching and annual nitrate–N loads for 77 river catchments from 1990 to 2018. Lag times between these losses and riverine loads were determined for 34 catchments but could not be determined in other catchments because they exhibited little change in nitrate–N leaching losses or loads. Lag times varied from 1 to 12 years according to factors like catchment size (Strahler stream order and altitude) and slope. For eight catchments where additional isotope and modelling data were available, the mean transit time for surface water at baseflow to pass through the catchment was on average 2.1 years less than, and never greater than, the mean lag time for nitrate–N, inferring our lag time estimates were robust. The median lag time for nitrate–N across the 34 catchments was 4.5 years, meaning that nearly half of these catchments wouldn’t exhibit decreases in nitrate–N because of practice change within the five years outlined in policy.

Inhibition of Aspergillus spp. and Penicillium spp. by Fatty Acids and Their Monoglycerides

2007 ◽  
Vol 70 (5) ◽  
pp. 1206-1212 ◽  
Author(s):  
CLELIA ALTIERI ◽  
DANIELA CARDILLO ◽  
ANTONIO BEVILACQUA ◽  
MILENA SINIGAGLIA
Keyword(s):  
Fatty Acids ◽  
Fungal Growth ◽  
Lag Time ◽  
Mold Growth ◽  
Penicillium Species ◽  
Colony Diameter ◽  
Gompertz Equation ◽  
Lag Times ◽  
Penicillium Spp ◽  
Palmitic Acids

The antifungal activity of three fatty acids (lauric, myristic, and palmitic acids) and their monoglycerides (monolaurin, monomyristic acid, and palmitin, respectively) against Aspergillus and Penicillium species in a model system was investigated. Data were modeled through a reparameterized Gompertz equation. The maximum colony diameter attained within the experimental time (30 days), the maximal radial growth rate, the lag time (i.e., the number of days before the beginning of radial fungal growth), and the minimum detection time (MDT; the number of days needed to attain 1 cm colony diameter) were evaluated. Fatty acids and their monoglycerides inhibited mold growth by increasing MDT and lag times. The effectiveness of the active compounds seemed to be strain and genus dependent. Palmitic acid was the most effective chemical against aspergilli, whereas penicilli were strongly inhibited by myristic acid. Aspergilli also were more susceptible to fatty acids than were penicilli, as indicated by the longer MDT.

scholarly journals Darwin’s naturalization hypothesis does not explain the spread of nonnative weed species naturalized in México

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5444
Author(s):  
Judith Sánchez-Blanco ◽  
Ernesto V. Vega-Peña ◽  
Francisco J. Espinosa-García
Keyword(s):  
Residence Time ◽  
Lag Phase ◽  
Herbarium Specimens ◽  
Weed Species ◽  
Species Groups ◽  
Biological Attributes ◽  
Darwin's Naturalization Hypothesis ◽  
Stochastic Events ◽  
Close Relatives ◽  
Darwin’S Naturalization Hypothesis

BackgroundDespite numerous tests of Darwin’s naturalization hypothesis (DNH) evidence for its support or rejection is still contradictory. We tested a DNH derived prediction stating that nonnative species (NNS) without native congeneric relatives (NCR) will spread to a greater number of localities than species with close relatives in the new range. This test controlled the effect of residence time (Rt) on the spread of NNS and used naturalized species beyond their lag phase to avoid the effect of stochastic events in the establishment and the lag phases that could obscure the NCR effects on NNS.MethodsWe compared the number of localities (spread) occupied by NNS with and without NCR using 13,977 herbarium records for 305 NNS of weeds. We regressed the number of localities occupied by NNSversus Rtto determine the effect of time on the spread of NNS. Then, we selected the species withRtgreater than the expected span of the lag phase, whose residuals were above and below the regression confidence limits; these NNS were classified as widespread (those occupying more localities than expected byRt) and limited-spread (those occupying fewer localities than expected). These sets were again subclassified into two groups: NNS with and without NCR at the genus level. The number of NNS with and without NCR was compared usingχ2tests and Spearman correlations between the residuals and the number of relatives. Then, we grouped the NNS using 34 biological attributes and five usages to identify the groups’ possible associations with spread and to test DNH. To identify species groups, we performed a nonmetric multidimensional scaling (NMDS) analysis and evaluated the influences of the number of relatives, localities, herbarium specimens,Rt, and residuals of regression. The Spearman correlation and the Mann–WhitneyUtest were used to determine if the DNH prediction was met. Additionally, we used the clustering objects on subsets of attributes (COSA) method to identify possible syndromes (sets of biological attributes and usages) associated to four groups of NNS useful to test DNH (those with and without NCR and those in more and fewer localities than expected byRt).ResultsResidence time explained 33% of the variation in localities occupied by nonnative trees and shrubs and 46% of the variation for herbs and subshrubs. The residuals of the regression for NNS were not associated with the number or presence of NCR. In each of the NMDS groups, the number of localities occupied by NNS with and without NCR did not significantly differ. The COSA analysis detected that only NNS with NCR in more and fewer localities than expected share biological attributes and usages, but they differ in their relative importance.DiscussionOur results suggest that DNH does not explain the spread of naturalized species in a highly heterogeneous country. Thus, the presence of NCR is not a useful characteristic in risk analyses for naturalized NNS.

THE MODE OF ACTION OF PENTOSAN POLYSULPHATE IN PLASMA

1987 ◽  
Author(s):  
S Béguin ◽  
H C Hemker
Keyword(s):  
Factor Viii ◽  
Linear Increase ◽  
Factor Ix ◽  
Factor X ◽  
Heparin Cofactor Ii ◽  
Normal Plasma ◽  
Viii And Ix ◽  
Pentosan Polysulphate ◽  
Lag Times ◽  
Prothrombinase Activity

We developed a method which enables as to compute the course of prothrombinase activity in clotting plasma (H.C. Hemker, G.M. Willems, S. Béguin: Thromb. Haemostas. 56, 9-17, 1986) and used this for a study of the effect of pentosan polysulphate (PPS) on thrombin generation.When added to normal plasma in the concentration range of 0-8 μg/ml PPS induces a linear increase of the pseudo first order decay constant of endogenous thrombin like heparin does, 1 ug of PPS being equivalent to 0.045 Aig of heparin. Contrary to heparin this action is partly (∼ 65%) dependent upon AT III and partly (∼ 35%) upon heparin cofactor II.In normal plasma PPS causes an inhibition of both extrinsic and intrinsic prothrombinase formation. Only in the intrinsic system an increase of the lag time of prothrombinase appearance is observed. Unlike heparin, PPS does not inhibit factor IXa induced thrombin formation neither does it inhibit prothrombinase formation in the presence of preactivated factor VIII. The prolongation of the lag times must therefore be ascribed to inhibition by PPS of the activation of factor VIII.The inhibition of extrinsic prothrombinase formation by PPS increases with progressive dilution of thromboplastin and is not seen in haemophilia A or B plasma. This demonstrates the existance of a factor VIII and IX dependent process in extrinsic coagulation that gains in importance when the potency of factgr VII-tissue factor complex decreases, i.e. the Josso pathway.PPS, but also heparin causes an unexplained increase of prothrombinase action in haemophIIic plasma. The same phenomenon may be expected to exist in normal plasma, be it obscured by a concomitant inhibition. This, together with the incomplete inhibition of factor VIII activation by PPS makes that we cannot use this inhibitor as a means to quantitate the Josso pathway. The best estimate that we can obtain is that, in the presence of 2% thromboplastin, the factor IX dependent activation of factor X contributes more then 20% to prothrombinase generation.

Effect of Ensiling and Rumen Digestion by Cattle on Weed Seed Viability

Weed Science ◽  
1991 ◽  
Vol 39 (1) ◽  
pp. 104-108 ◽  
Author(s):  
Robert E. Blackshaw ◽  
Lyle M. Rode
Keyword(s):  
Time Course ◽  
Seed Viability ◽  
Grass Species ◽  
Lag Phase ◽  
Rapid Decline ◽  
Weed Species ◽  
Embryo Viability ◽  
Seed Survival ◽  
Gradual Process ◽  
Broadleaf Species

Studies were conducted to determine the effect of ensiling and/or rumen digestion by cattle on the germination and viability of several common weed species. Seed survival of grass species subjected to ensiling and/or rumen digestion tended to be less than that of broadleaf species. Downy brome, foxtail barley, and barnyardgrass were nonviable after either ensiling for 8 weeks or rumen digestion for 24 h. Some green foxtail (17%) and wild oats (0 to 88%) seeds survived digestion in the rumen but were killed by the ensiling process. Varying percentages of seeds of kochia, redroot pigweed, common lambsquarters, wild buckwheat, round-leaved mallow, and field pennycress remained viable after ensiling (3 to 30%), rumen digestion (15 to 98%), and ensiling plus rumen digestion (2 to 19%). A time course study of rumen digestion indicated that loss of seed viability often was not a gradual process. With some species, there was an initial lag phase while degradation of the protective seed coat likely occurred, followed by a rapid decline in embryo viability. The diet fed to livestock appeared to affect viability losses caused by rumen digestion. Estimates of seed survival with varying rates of passage through the rumen due to differing ratios of grain to forage in the diet are presented.

Relating initial paraquat injury to final efficacy in selected weed species influenced by environmental conditions

2020 ◽  
pp. 1-10
Author(s):  
Nick T. Harre ◽  
Garth W. Duncan ◽  
Julie M. Young ◽  
Bryan G. Young
Keyword(s):  
Environmental Factors ◽  
Negative Relationship ◽  
Injury Rate ◽  
Time Of Day ◽  
Palmer Amaranth ◽  
Shoot Biomass ◽  
Lag Phase ◽  
Progression Rate ◽  
Weed Species ◽  
Time Of Application

Abstract Weed control of paraquat can be erratic and may be attributable to differing species sensitivity and/or environmental factors for which minor guidance is available on commercial labels. Therefore, the objectives of this research were to quantify selectivity of paraquat across select weed species and the influence of environmental factors. Experiments were performed under controlled conditions in the greenhouse and growth chamber. Compared with purple deadnettle (dose necessary to reduce shoot biomass by 50% = 39 g ai ha−1), waterhemp, Palmer amaranth, giant ragweed, and horseweed were 4.9, 3.3, 1.9, and 1.3 times more sensitive to paraquat, respectively. The injury progression rate over 3 d after treatment (DAT) was a more accurate predictor of final efficacy at 14 DAT than the lag phase until symptoms first appeared. For example, at the 17.5 g ha−1 dose, the injury rate of waterhemp and Palmer amaranth was, on average, 3.6 times greater than that of horseweed and purple deadnettle. The influence of various environmental factors on paraquat efficacy was weed specific. Applications made at sunrise improved control of purple deadnettle over applications at solar noon or sunset. Lower light intensities (200 or 600 μmol m−2 s−1) surrounding the time of application improved control of waterhemp and horseweed more than 1,000 μmol m−2 s−1. Day/night temperatures of 27/16 C improved horseweed and purple deadnettle control compared with day/night temperatures of 18/13 C. Though control was positively associated with injury rates in the application time of day and temperature experiments, a negative relationship was observed for waterhemp in the light-intensity experiment. Thus, although there are conditions that enhance paraquat efficacy, the specific target species must also be considered. These results advocate paraquat dose recommendations, currently based on weed height, be expanded to address sensitivity differences among weeds. Moreover, these findings contrast with paraquat labels stating temperatures of 13 C or lower do not reduce paraquat efficacy.

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