Temporal Pattern Of Emergence Research Articles

Multiple climate change stressors reduce the emergence success of gravel-spawning fish species and alter temporal emergence patterns

Climate change, with its profound effects on stream sediment, hydrological, and temperature dynamics, will exacerbate impacts on habitat conditions for many species, particularly those with vulnerable early life stages relying on the hyporheic zone, such as gravel-spawning fishes. Due to the complex and interactive nature of multiple stressor effects, we employed large-scale outdoor mesocosms to systemically test how the reproductive success of three gravel-spawning fish species brown trout (Salmo trutta), nase, (Chrondrostoma nasus) and Danube salmon (Hucho hucho) was affected by individual and combined effects of warming (+3–4 °C), fine sediment (increase in <0.85 mm by 22 %) and low-flow (eightfold discharge-reduction). Fine sediment had the most detrimental effect on emergence rate and fry length in all three species, reducing the emergence rate to zero in brown trout, 9 % in nase, and 4 % in Danube salmon. The emergence mortality caused by fine sediment surpassed that of hatching distinctly, suggesting that negative effects due to hypoxia were considerably exacerbated by entombment. Warming had only minor effects as a single stressor, but low flow reduced emergence rates of the spring spawning species nase and Danube salmon by 8 and 50 %, respectively. In combined treatments including fine sediment, however, the emergence success of all three species responded strongly negatively, even in the cyprinid species nase, which showed little interactive effects between stressors regarding hatching success. Warming and fine sediment also led to the earlier emergence of fry, implying a risk of asynchrony with available food resources. This study dramatically shows that climate change can have deleterious impacts on the reproductive success of gravel-spawning fish species, irrespective of taxonomic or ecological traits.

Expansion and collapse of VEGF diversity in major clades of the animal kingdom

Together with the platelet-derived growth factors (PDGFs), the vascular endothelial growth factors (VEGFs) form the PDGF/VEGF subgroup among cystine knot growth factors. The evolutionary relationships within this subgroup have not been examined thoroughly to date. Here, we comprehensively analyze the PDGF/VEGF growth factors throughout all animal phyla and propose a phylogenetic tree. Vertebrate whole-genome duplications play a role in expanding PDGF/VEGF diversity, but several limited duplications are necessary to account for the temporal pattern of emergence. The phylogenetically oldest PDGF/VEGF-like growth factor likely featured a C-terminus with a BR3P signature, a hallmark of the modern-day lymphangiogenic growth factors VEGF-C and VEGF-D. Some younger VEGF genes, such as VEGFB and PGF, appeared completely absent in important vertebrate clades such as birds and amphibia, respectively. In contrast, individual PDGF/VEGF gene duplications frequently occurred in fish on top of the known fish-specific whole-genome duplications. The lack of precise counterparts for human genes poses limitations but also offers opportunities for research using organisms that diverge considerably from humans.Graphical abstractSources for the graphical abstract: 326 MYA and older [1]; 72–240 MYA [2]; 235–65 MYA [3]

An evaluation of crustacean and rotifer diversity and composition in a temporary pond metacommunity: Comparing results from field samples and a hatching experiment

Abstract Many aquatic invertebrates that inhabit temporary ponds produce resting forms to overcome the dry period, building up the egg bank. When the wet phase returns, the resting forms hatch and the community is restored, and then pioneer species may have a major influence on how the pond community will assemble. We aimed to evaluate the diversity of an initial pond metacommunity by comparing the early active metacommunity collected in the field and the egg bank metacommunity (by carrying out a hatching experiment) of 32 Mediterranean temporary ponds. We hypothesised that both metacommunities would be similar but also that species turnover may play an important role, and that γ diversity would be similar with both approaches. After the identification and counting of rotifers and crustaceans in both metacommunities (i.e. the field vs. the experiment) we performed a Partial Triadic Analysis comparing the field metacommunity with those corresponding to each of the eight times the hatching experiment was checked for hatchlings. Furthermore, we compared the field and experimental metacommunities with a PROTEST analysis and identified the taxa responsible for differences between metacommunities with a SIMPER analysis. We assessed γ diversity using a size‐based rarefaction curve and an evenness profile and explored β diversity and its components (turnover and nestedness) for the two metacommunities. Our experimental results showed differences in the temporal pattern of emergence between groups of organisms, with copepods, rotifers, and anostracans appearing first, but ostracods and rotifers reaching the highest diversity at the end of the experiment. The active and experimental pioneer metacommunities were similar according to a Procrustes analysis. Nevertheless, β diversity was high in both metacommunities and the differences among ponds and between both assemblages were mostly explained by species turnover. Both the active and experimental pond metacommunities showed some exclusive species that may be more difficult to uncover with only one type of approach. Furthermore, the high β diversity observed indicates that each temporary pond is an important contributor to γ diversity in the metacommunity. These results show that hatching experiments provide information that is complementary to standard sampling of the active community, and consequently is a useful tool to uncover pond biodiversity.

Escaping stochastic extinction of mutant virus: Temporal pattern of emergence of drug resistance within a host

After infecting a host, a viral strain may increase rapidly within the body and produce mutants with a faster proliferation rate than the virus itself. However, most of the mutants become extinct because of the stochasticity caused by the small number of infected cells. In addition, the mean growth rate of a mutant strain decreases with time because the number of susceptible target cells is reduced by the original strain. In this study, we calculated the fraction of mutants that can escape stochastic extinction, based on a continuous-time branching process with a time-dependent growth rate. We analyzed two cases differing in the mode of viral transmission: (1) an infected cell transmits the virus through cell-to-cell contact with a susceptible target cell; (2) an infected cell releases numerous free viral particles that subsequently infect susceptible target cells. The chance for a mutant strain to be established decreases with time after infection of the original type, and it may oscillate before convergence at the stationary value. We then calculated the probability of escaping stochastic extinction for a drug-resistant mutant when a patient received an antiviral drug that suppressed the original strain. Combining the rate of mutant production from the original strain and the chance of escaping stochastic extinction, the number of emerging drug-resistant mutations may have two peaks: one soon after the infection of the original type and the second at the start of antiviral drug administration.

Biochemical characterization of mouse d-aspartate oxidase

D-amino acids research field has recently gained an increased interest since these atypical molecules have been discovered to play a plethora of different roles. In the mammalian central nervous system, d-aspartate (D-Asp) is critically involved in the regulation of glutamatergic neurotransmission by acting as an agonist of NMDA receptor. Accordingly, alterations in its metabolism have been related to different pathologies. D-Asp shows a peculiar temporal pattern of emergence during ontogenesis and soon after birth its brain levels are strictly regulated by the catabolic enzyme d-aspartate oxidase (DASPO), a FAD-dependent oxidase. Rodents have been widely used as in vivo models for deciphering molecular mechanisms and for testing novel therapeutic targets and drugs, but human targets can significantly differ. Based on these considerations, here we investigated the structural and functional properties of the mouse DASPO, in particular kinetic properties, ligand and flavin binding, oligomerization state and protein stability. We compared the obtained findings with those of the human enzyme (80% sequence identity) highlighting a different oligomeric state and a lower activity for the mouse DASPO, which apoprotein species exists in solution in two forms differing in FAD affinity. The features that distinguish mouse and human DASPO suggest that this flavoenzyme might control in a distinct way the brain D-Asp levels in different organisms.

Temporal Patterns of Emergence and Spatial Distribution of Sulcal Pits During Fetal Life.

Sulcal pits are thought to represent the first cortical folds of primary sulci during neurodevelopment. The uniform spatial distribution of sulcal pits across individuals is hypothesized to be predetermined by a human-specific protomap which is related to functional localization under genetic controls in early fetal life. Thus, it is important to characterize temporal and spatial patterns of sulcal pits in the fetal brain that would provide additional information of functional development of the human brain and crucial insights into abnormal cortical maturation. In this paper, we investigated temporal patterns of emergence and spatial distribution of sulcal pits using 48 typically developing fetal brains in the second half of gestation. We found that the position and spatial variance of sulcal pits in the fetal brain are similar to those in the adult brain, and they are also temporally uniform against dynamic brain growth during fetal life. Furthermore, timing of pit emergence shows a regionally diverse pattern that may be associated with the subdivisions of the protomap. Our findings suggest that sulcal pits in the fetal brain are useful anatomical landmarks containing detailed information of functional localization in early cortical development and maintaining their spatial distribution throughout the human lifetime.

Emergence ecology of the critically endangered Urothemis edwardsii in a new colonized site in El Kala National Park (Algeria): conservation implications

Urothemis edwardsii is one of the most threatened dragonfly species in the Mediterranean. Recent investigations and conservation efforts have increased the local geographic distribution of the species in Northeast Algeria, where a new population (named El Graeate) has been discovered. In the absence of information about the biology and behavior of U. edwardsii in this new site, a study was conducted on the emergence ecology of the species taking into account the temporal pattern of emergence, sex ratio, body size and microhabitat selection. Emergence, which was quite asynchronous, lasted for 50 days, with 50% of the population emerging within the first half of the period. Sex ratio at emergence was slightly female biased despite the absence of sexual size dimorphism, suggesting that size is not the only driving force behind mortality bias during the larval stage. There was a slight seasonal increase in the body size of exuviae (exoskeletons) in both sexes. Microhabitat selection, assessed as the vertical stratification of exuviae at ecdysis, was positively correlated with the height of supporting plants, but the relationship reached a plateau suggesting that there are predetermined limits to the vertical distribution of exuviae. These data will be essential for the future species protection, restoration and management attempts in the region.

Development and Validation of a Predictive Model for Seedling Emergence of Volunteer Canola (Brassica napus) Under Semi-Arid Climate

Volunteer canola (Brassica napus L.) can damage the production of subsequent canola crops and other crops. Timely and more accurate control could be developed if there is a better understanding of its temporal emergence patterns. The objectives of this study were to develop and validate a predictive model of emergence for B. napus under semi-arid conditions based on thermal time (TT). Experiments were conducted during 3 years to obtain cumulative seedling emergence data and used to develop and validate the model. A Weibull function was fitted to cumulative seedling emergence and TT. The model closely fitted the observed emergence patterns, accounting for 99% of the variation observed. According to this model, seedling emergence of B. napus started at 56.1 TT and increased to 50 and 95% of maximum seedling emergence at 86.3 and 105.4 TT, respectively. Validation was performed with the Weibull model and two logistics models (taken from the literature) developed under different climate conditions. The validation indicated that the Weibull model performed better than the logistic models. The Weibull model proposed is robust enough and could be useful as a predictive tool for effective control of B. napus under semi-arid climate.

Thermal regulation of secondary dormancy induction inPolygonum aviculareseeds: a quantitative analysis using the hydrotime model

AbstractFor seed banks showing seasonal changes in their dormancy level, the possibility of predicting temporal patterns of emergence depends on establishing a robust relationship between temperature and the rate of dormancy loss and induction. However, although the effect of temperature on dormancy loss has been extensively studied, less work has been advocated to the quantification of temperature effects on dormancy induction. In the present work, we quantified temperature regulation of dormancy induction inPolygonum aviculareseeds using the hydrotime model. To study induction into secondary dormancy, seeds previously released from primary dormancy through stratification at 5°C were stored at dormancy-inductive temperatures of 10, 15, 20 and 25°C for different periods. During storage, seeds were germinated at different temperatures and water potentials, and hydrotime model parameters were derived. Changes in hydrotime model parameters (mean base water potential for germination and its standard deviation, and the hydrotime required for germination) during dormancy induction were described by adjusting exponential equations. Obtained results indicated a minimum temperature for dormancy induction of 8.7°C and the existence of a bi-linear relationship between rate of induction into secondary dormancy and storage temperature, in which storage temperatures around 25°C showed a higher dormancy induction rate than those below 20°C. Developed model equations were then used to predict changes in germination behaviour during dormancy induction at different temperatures, showing a good agreement between simulated and observed values.

Spatial and temporal heterogeneity of infectious hematopoietic necrosis virus in Pacific Northwest salmonids

The aquatic rhaboviral pathogen infectious hematopoietic necrosis virus (IHNV) causes acute disease in juvenile fish of a number of populations of Pacific salmonid species. Heavily managed in both marine and freshwater environments, these fish species are cultured during the juvenile stage in freshwater conservation hatcheries, where IHNV is one of the top three infectious diseases that cause serious morbidity and mortality. Therefore, a comprehensive study of viral genetic surveillance data representing 2590 field isolates collected between 1958 and 2014 was conducted to determine the spatial and temporal patterns of IHNV in the Pacific Northwest of the contiguous United States. Prevalence of infection varied over time, fluctuating over a rough 5–7yearcycle. The genetic analysis revealed numerous subgroups of IHNV, each of which exhibited spatial heterogeneity. Within all subgroups, dominant genetic types were apparent, though the temporal patterns of emergence of these types varied among subgroups. Finally, the affinity or fidelity of subgroups to specific host species also varied, where UC subgroup viruses exhibited a more generalist profile and all other subgroups exhibited a specialist profile. These complex patterns are likely synergistically driven by numerous ecological, pathobiological, and anthropogenic factors. Since only a few anthropogenic factors are candidates for managed intervention aimed at improving the health of threatened or endangered salmonid fish populations, determining the relative impact of these factors is a high priority for future studies.

Partial bivoltinism and emergence patterns in the North African endemic damselfly Calopteryx exul: conservation implications

AbstractCalopteryx exul is an endemic endangered damselfly that suffers considerable habitat degradation and local extinctions throughout its geographic range. Although recent studies have investigated its distribution, ecology and larval systematics, the life history of the species is still unknown. In this study, a field survey was conducted to determine larval development, temporal pattern of emergence and teneral spatial distribution of the species in the Seybouse watershed, north‐east Algeria. Larval growth was investigated in two populations: one at about 200 m (low‐elevation population) and the second at 600 m of elevation (high‐elevation population). The species showed partial bivoltine life cycle in both low‐ and high‐elevation population. The temporal pattern of emergence of the first flight season of the year at low‐elevation population was asynchronous with an emergence season lasting 46 days and half of the population emerging in 15 days. The second flight season was shorter with a most likely smaller population size. Sex ratio at emergence was slightly male biased. After ecdysis, tenerals stayed next to the water within a mean distance of 4.76 ± 4.35 m (± SD) with no significant difference between sexes. Conservation measures that should be taken into account in the elaboration of future management plans for the species are discussed.

Spatial and temporal emergence pattern of Lyme disease in Virginia.

The emergence of infectious diseases over the past several decades has highlighted the need to better understand epidemics and prepare for the spread of diseases into new areas. As these diseases expand their geographic range, cases are recorded at different geographic locations over time, making the analysis and prediction of this expansion complicated. In this study, we analyze spatial patterns of the disease using a statistical smoothing analysis based on areal (census tract level) count data of Lyme disease cases in Virginia from 1998 to 2011. We also use space and space-time scan statistics to reveal the presence of clusters in the spatial and spatiotemporal distribution of Lyme disease. Our results confirm and quantify the continued emergence of Lyme disease to the south and west in states along the eastern coast of the United States. The results also highlight areas where education and surveillance needs are highest.

Emergence ecology of Orthetrum cancellatum: temporal pattern and microhabitat selection (Odonata: Libellulidae)

Summary. Knowledge of both phenology and habitat selection are important assets for conservation and management purposes. Generally, aquatic insect species have an optimal season and larval microhabitat in which their survival and reproductive success are high. In odonates, emergence is usually a seasonal-restricted process during which the insect has to find a good timing and a convenient microhabitat to carry out the final ecdysis out of the water. We investigated temporal emergence pattern and microhabitat choice in Orthetrum cancellatum in northeast Algeria, which represents the southern limit of its distribution range. The emergence season lasted 56 days starting from 30.IV and ended on 25.VI, showing a peak on 19.V. The time by which 50% of the annual population has emerged (EM50) was 20 days and the sex ratio was slightly male-biased, with 51.53%. Final instar larvae chose areas with relatively dense vegetation, and this selection was positively dependent on the mean vegetation height and not on sex or body size. Height selection was positively dependent only on the support height that the larva chose. We suggest that larvae consider both predation risks and mainly local microclimate to select their emergence site.

Do Common Waterhemp (Amaranthus rudis) Seedling Emergence Patterns Meet Criteria for Herbicide Resistance Simulation Modeling?

A study was conducted to quantify the magnitude and sources of variation in common waterhemp temporal patterns of emergence over 1 yr. In 2008 and 2010, emergence patterns in the absence of soil disturbance were determined for replicated samples of maternal families (progeny from one individual) separately harvested during the previous year from four plants within each of four agricultural fields (16 maternal families yr−1) at a university research farm near Urbana, IL. Combining data across years, variance partitioning indicated that seed sample within maternal family explained 48% of total variation in the percentage of viable, buried seeds that produced seedlings. Differences within, rather than among, maternal families also accounted for large fractions (60 to 99%) of total variation in cumulative percentage emergence at specific points during the growing season. Within years, seed samples characterized by delayed or accelerated emergence patterns did not originate from specific maternal plants. These results indicate that common waterhemp seed populations are without strong maternal plant effects that limit emergence to narrow intervals within the overall emergence period. Thus, results of this study support the use of contemporary approaches for modeling herbicide resistance evolution in common waterhemp, which assume seedling cohorts contain offspring from all individuals occurring within the maternal population.

Selective manipulation of aging: a novel strategy for the treatment of neurodegenerative disorders

Aging is the major risk factor for the development of human neurodegenerative maladies such as Alzheimer's, Huntington's and Parkinson's diseases, and prion disorders, all of which stem from toxic protein aggregation. Although sporadic cases typically onset during the patient's seventh decade of life or later, mutation-linked, familial disorders manifest during the fifth or sixth decade of life. This common temporal emergence pattern suggests that slowing aging can postpone the onset of these maladies and alleviate their symptoms once emerged. Studies in worms and flies that express disease-linked aggregative proteins revealed that reducing the activity of the insulin / insulin-like growth factor (IGF) signalling (IIS), a prominent aging regulatory pathway, protects these animals from toxic protein aggregation. The therapeutic potential of this approach has been tested and confirmed in mammals as reducing the activity of the IGF1 signalling cascade partially protects Alzheimer's-model mice from premature death, and behavioural and pathological impairments associated with the disorder. Here we review the recent advances in the field, describe the known mechanistic links between toxic protein aggregation, neurodegenerative disorders and the aging process and delineate recent studies that point at IGF1 signalling inhibitors as promising therapies for the treatment of various late-onset neurodegenerative disorders.

Aging, Protein Aggregation, Chaperones and Neurodegenerative Disorders: Mechanisms of Coupling and Therapeutic Opportunities

Late onset is a key unifying feature of human neurodegenerative maladies such as Alzheimer’s and Parkinson’s diseases and prion disorders. While sporadic cases typically emerge during the patient’s seventh decade of life or later, mutation-linked, familial cases manifest during the fifth or sixth decade. This common temporal emergence pattern raises the prospect that slowing aging may prevent the accumulation of toxic protein aggregates that lead to the development of these disorders, postpone the onset of these maladies, and alleviate their symptoms once emerged. Invertebrate-based studies indicated that reducing the activity of insulin/IGF signaling (IIS), a prominent aging regulatory pathway, protects from neurodegeneration-linked toxic protein aggregation. The validity of this approach has been tested and confirmed in mammals as reducing the activity of the IGF-1 signaling pathway-protected Alzheimer’s model mice from the behavioral and biochemical impairments associated with the disease. Here I review the recent advances in the field, describe the known mechanistic links between toxic protein aggregation and the aging process, and delineate the future therapeutic potential of IIS reduction as a treatment for various neurodegenerative disorders.

Phenology of Stable Fly (Diptera: Muscidae) Larvae in Round Bale Hay Feeding Sites in Eastern Nebraska

The temporal and spatial patterns of adult stable sy, Stomoxys calcitrans (L.), emer- gence from six sites where large round baled hay had been provided to pasture cattle as winter feed were studied using emergence traps. The substrate at these sites, consisting of waste hay mixed with bovine manure and urine, provided an excellent developmental habitat for immature stable sies. Stable sies were the most frequently collected sy emerging from these sites with a yearly average of 1,581 emerging per square meter. Stable sy emergence from these sites began in early May (235 annual accumulated Day-Degree 10C (DD10)), peaked in late June and early July (400 Ð900 DD10) and then dropped to very low levels in late July (900 DD10). The temporal pattern of stable sy emergence from the hay feeding sites differed from that of adult populations measured with sticky traps. Adult populations increased in the spring before signiÞcant emergence from the hay feeding sites was observed, dipped in midsummer soon after the hay feeding sites became nonproductive, and then rebounded in the late summer when emergence from the hay feeding sites was very low. The drop in productivity of the hay feeding sites appeared to be because of endogenous factors associated with decomposition of the substrate rather than temperature or precipitation. Winter hay feeding sites appear to be primary sources of stable sies during the early summer, however, they are not responsible for late summer and fall stable sy populations. Overall, the inner most 2-m annulus of the hay feeding sites was the most productive, however, spatial variation among sites was observed. The sex ratio of emerging sies did not differ from 1:1 and the temporal pattern of emergence was similar for males and females. Although several other species of sies were collected emerging from the hay feeding site substrate, house sies (Musca domestica L.) were notably absent.

Temporal specification of blood progenitors from mouse embryonic stem cells and induced pluripotent stem cells

The efficient and reproducible generation of differentiated progenitors from pluripotent stem cells requires the recapitulation of appropriate developmental stages and pathways. Here, we have used the combination of activin A, BMP4 and VEGF under serum-free conditions to induce hematopoietic differentiation from both embryonic and induced pluripotent stem cells, with the aim of modeling the primary sites of embryonic hematopoiesis. We identified two distinct Flk1-positive hematopoietic populations that can be isolated based on temporal patterns of emergence. The earliest arising population displays characteristics of yolk sac hematopoiesis, whereas a late developing Flk1-positive population appears to reflect the para-aortic splanchnopleura hematopoietic program, as it has reduced primitive erythroid capacity and substantially enhanced myeloid and lymphoid potential compared with the earlier wave. These differences between the two populations are accompanied by differences in the expression of Sox17 and Hoxb4, as well as in the cell surface markers AA4.1 and CD41. Together, these findings support the interpretation that the two populations are representative of the early sites of mammalian hematopoiesis.

A Thermal Time Model to Predict Corn Poppy (Papaver rhoeas) Emergence in Cereal Fields

Corn poppy is the most abundant broad-leaved weed in winter cereals of Mediterranean climate areas and causes important yield losses in wheat. Knowledge of the temporal pattern of emergence will contribute to optimize the timing of control measures, thus maximizing efficacy. The objectives of this research were to develop an emergence model on the basis of soil thermal time and validate it in several localities across Spain. To develop the model, monitoring of seedling emergence was performed weekly during the growing season in a cereal field located in northeastern Spain, during 3 yr. Cumulative thermal time from sowing date was used as the independent variable for predicting cumulative emergence. The Gompertz model was fitted to the data set of emergences. A base temperature of 1.0 C was estimated through iteration for maximum fit. The model accounted for 91% of the variation observed. Model validation in several localities and years showed general good performance in predicting corn poppy seedling emergence ( values ranging from 0.64 to 0.99 and root-mean-square error from 4.4 to 24.3). Ninety percent emergence was accurately predicted in most localities. Results showed that the model performs with greater reliability when significant rainfall (10 mm) occurs within 10 d after crop sowing. Complemented with in-field scouting, it may be a useful tool to better timing control measures in areas that are homogeneous enough regarding climate and crop management.

Los huevos falsos (SAGs) facilitan el comportamiento social de emergencia en las crías de la tortuga laúd Dermochelys coriacea (Testudines: Dermochelyidae)

Hatchling emergence to the beach surface from deep sand nests occurs without parental care. Social behaviour among siblings is crucial to overcome this first challenge in sea turtles life. This study, carried out at the Caribbean coast of Colombia, describes the emergence social behaviour of hatchlings from eight nests, and assess the nests translocation effects on temporal patterns of emergence. For the first time, we propose that space released by dehydration of shelled albumen globes (SAGs) at the top of the clutch, might be a reproductive advantage, while facilitating neonates to group together in a very limited space, and favouring the synchrony of emergence. The mean time of groups emergence was of 3.3 days, varying between 1 and 6 days. We found that relocation of the nests did not significantly affect the temporal pattern of emergence, which was mainly nocturnal (77.7% of natural nests and 81.7% of translocated ones). The maximum number of emergences to the surface occurred at the lowest air temperatures (22:00h-06:00h). The selective advantage of this pattern is probably related to the greater rate of predation and mortality by hyperthermia observed during the day.