Dauer juvenile longevity and stress tolerance in natural populations of entomopathogenic nematodes: is there a relationship?

2002 ◽  
Vol 32 (6) ◽  
pp. 717-725 ◽  
Author(s):  
P.S. Grewal ◽  
X. Wang ◽  
R.A.J. Taylor
Keyword(s):  
Stress Tolerance ◽  
Entomopathogenic Nematodes ◽  
Natural Populations

Natural Populations of Entomopathogenic Nematodes (Rhabditida: Heterorhabditidae, Steinernematidae) from the Hawaiian Islands

1991 ◽  
Vol 20 (1) ◽  
pp. 211-216 ◽  
Author(s):  
Arnold H. Hara ◽  
Randy Gaugler ◽  
Harry K. Kaya ◽  
Lynn M. Lebeck
Keyword(s):  
Entomopathogenic Nematodes ◽  
Hawaiian Islands ◽  
Natural Populations

scholarly journals Host Adaptation in Entomopathogenic Nematodes: An Approach to Enhancing Biological Control Potential

1996 ◽  
Author(s):  
Itamar Glazer ◽  
Randy Gaugler ◽  
Yitzhak Spiegel ◽  
Edwin Lewis
Keyword(s):  
Entomopathogenic Nematodes ◽  
Insect Pests ◽  
Lectin Binding ◽  
Natural Populations ◽  
Foraging Strategies ◽  
Host Recognition ◽  
Field Activity ◽  
Biological Control Potential ◽  
The Common

The overall objective of our research was to develop methods to match species of entomopathogenic nematodes against the insect pests which they would be best adapted to control. The underlying hypothesis for this work was that entomopathogenic nematodes should be most effective when used against insect species to which they are naturally adapted to parasitize. Toward this end, we undertook a number of related studies focusing primarily on nematode foraging strategies. We found that foraging strategies affected host associations directly and indirectly. Nematodes' responses to host cues, and the role of their sensory organs based on lectin binding, led to new approaches to determining host range for these parasites. Based on this work, we developed a laboratory bioassay of host recognition behavior designed to predict field results. We also determined that nematodes that forage in a stationary manner (ambushers) have a slower metabolic rate than do active forgers (cruisers), thus their infective stage juveniles are longer lived. This study helps predict the duration of field activity after application and may partially explain field distributions of natural populations of entomopathogenic nematodes. The common thread linking all of these studies was that they led to a deeper understanding of the associations between entomopathogenic nematodes and insects as hosts.

scholarly journals Genomic Variation Landscape of the Model Salt Cress Eutrema salsugineum

2021 ◽  
Vol 12 ◽  
Author(s):  
Xiaojuan Wang ◽  
Hua Rao ◽  
Jianxiang Ma ◽  
Xiaodan Chen ◽  
Guanglin Li ◽  
...  
Keyword(s):  
Stress Tolerance ◽  
Local Adaptation ◽  
Molecular Mechanisms ◽  
Natural Populations ◽  
Northern China ◽  
Genomic Variation ◽  
Forward Genetics ◽  
Local Adaptations ◽  
Salt Cress ◽  
Eutrema Salsugineum

Eutrema salsugineum has long been used as the model for examining salt and other abiotic stress in plants. In addition to the forward genetics approaches widely used in the lab, natural variations undoubtedly will provide a rich genetic resource for studying molecular mechanisms underlying the stress tolerance and local adaptation of this species. We used 90 resequencing whole genomes of natural populations of this species across its Asian and North American distributions to detect the selection signals for genes involved in salt and other stresses at the species-range level and local distribution. We detected selection signals for genes involved in salt and other abiotic tolerance at the species level. In addition, several cold-induced and defense genes showed selection signals due to local adaptation in North America-NE Russia or northern China, respectively. These variations and findings provide valuable resources for further deciphering genetic mechanisms underlying the stress tolerance and local adaptations of this model species.

Transcriptome analysis of stress tolerance in entomopathogenic nematodes of the genus Steinernema

2016 ◽  
Vol 46 (2) ◽  
pp. 83-95 ◽  
Author(s):  
Mor Yaari ◽  
Adi Doron-Faigenboim ◽  
Hinanit Koltai ◽  
Liora Salame ◽  
Itamar Glazer
Keyword(s):  
Stress Tolerance ◽  
Transcriptome Analysis ◽  
Entomopathogenic Nematodes

scholarly journals Frequency-dependent hybridization contributes to habitat segregation in monkeyflowers

2021 ◽  
Author(s):  
Katherine Toll ◽  
David Lowry
Keyword(s):  
Stress Tolerance ◽  
Competitive Ability ◽  
Field Experiments ◽  
Natural Populations ◽  
Seed Viability ◽  
Spatial Segregation ◽  
Closely Related Species ◽  
Frequency Dependent ◽  
Close Relatives ◽  
Competition For Resources

Spatial segregation of closely related species is usually attributed to differences in stress tolerance and competitive ability. For both animals and plants, reproductive interactions between close relatives can impose a fitness cost that is more detrimental to the rarer species. Frequency-dependent mating interactions may thus prevent the establishment of immigrants within heterospecific populations, maintaining spatial segregation of species. Despite strong spatial segregation in natural populations, two sympatric California monkeyflowers (Mimulus nudatus and M. guttatus) survive and reproduce in the other's habitat when transplanted reciprocally. We hypothesized that a frequency-dependent mating disadvantage maintains spatial segregation of these monkeyflowers during natural immigration. To evaluate this hypothesis, we performed two field experiments. First, we experimentally added immigrants in varying numbers to sites dominated by heterospecifics. Second, we reciprocally transplanted arrays of varying resident and immigrant frequency. Immigrant seed viability decreased with conspecific rarity for M. guttatus, but not M. nudatus. We observed immigrant minority disadvantage for both species, but driven by different factors- frequency-dependent hybridization for M. guttatus, and competition for resources and/or pollinators for M. nudatus. Overall, our results suggest a potential major role for reproductive interference in spatial segregation that should be evaluated along with stress tolerance and competitive ability.

scholarly journals Molecular and morphological characterization related to salt stress in natural populations of the Medicago polymorpha species

2021 ◽  
pp. 484-493
Author(s):  
Abdelnasser Bakhti ◽  
Fatima-Zohra FyadLameche
Keyword(s):  
Salt Stress ◽  
Molecular Markers ◽  
Stress Tolerance ◽  
Growth Parameters ◽  
Natural Populations ◽  
Principal Component ◽  
Stem Length ◽  
Saline Stress ◽  
Medicago Polymorpha ◽  
R Ratio

Legumes are important crops due to their nutritional benefits as well as their utility in agriculture rotation. The morphological and molecular markers can elucidate plant response to stresses. In the present study, we investigated indicators of molecular polymorphism related to salt stress tolerance in natural populations of Medicago polymorpha species. The plant samples were collected from different geographical sites in western Algeria. Morphological growth parameters such as root length stem length of plant and T/R ratio were examined under four NaCl concentration levels (0, 68, 102 and 137 mM). The molecular study was carried out using SSR molecular markers on all the studied populations. Significant differences were observed in mean squares of analysis of variance, indicating relation between geographical origins and populations. This analysis showed the existence of two contrasted populations (DZ221 and DZ312). DZ221 is a relatively salt tolerant, and DZ312 is sensitive. The Principal Component Analysis (PCA) was calculated using the PCA function, revealing a high correlation between the morphological traits and the geographical distribution of populations. It divided populations into four distinguished groups respecting their origin geographical sites. The molecular results of the polymorphism degree showed that the natural populations of M. Polymorpha species were strictly homozygous (100%). The PIC index of the three microsatellites was very informative (0.77). Additionally, the results showed that both microsatellites (FMT11 and MTIC297) revealed some alleles detected in the tolerant population (DZ221) suggesting that they can be used as indicators of saline stress tolerance adaptation.

High-voltage electron microscopy of maxillary gland of spirochete-infected brine shrimp: lesion of efferent tubule

1988 ◽  
Vol 46 ◽  
pp. 362-363
Author(s):  
G. E. Tyson ◽  
M. J. Song
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Brine Shrimp ◽  
Natural Populations ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Infected Adult

Natural populations of the brine shrimp, Artemia, may possess spirochete- infected animals in low numbers. The ultrastructure of Artemia's spirochete has been described by conventional transmission electron microscopy. In infected shrimp, spirochetal cells were abundant in the blood and also occurred intra- and extracellularly in the three organs examined, i.e. the maxillary gland (segmental excretory organ), the integument, and certain muscles The efferent-tubule region of the maxillary gland possessed a distinctive lesion comprised of a group of spirochetes, together with numerous small vesicles, situated in a cave-like indentation of the base of the tubule epithelium. in some instances the basal lamina at a lesion site was clearly discontinuous. High-voltage electron microscopy has now been used to study lesions of the efferent tubule, with the aim of understanding better their three-dimensional structure.Tissue from one maxillary gland of an infected, adult, female brine shrimp was used for HVEM study.

Effect of acid deposition on trichome morphology and dogwood anthracnose biology

1992 ◽  
Vol 50 (1) ◽  
pp. 840-841
Author(s):  
Kyle T. Thornham ◽  
R. Jay Stipes ◽  
Randolph L. Grayson
Keyword(s):  
Acid Deposition ◽  
Disease Incidence ◽  
Natural Populations ◽  
Tree Disease ◽  
Flowering Dogwood ◽  
Discula Destructiva ◽  
Disease Induction ◽  
Dogwood Anthracnose ◽  
Trichome Morphology ◽  
Precipitation Events

Dogwood anthracnose, caused by Discula destructiva (1), is another new catastrophic tree disease that has ravaged natural populations of the flowering dogwood (Cornus florida) in the Appalachians over the past 15 years, and the epidemic is prognosticated to continue (2). An estimated 9.5 million acres have been affected, primarily in the Appalachian Mountains, from VA southwards, alone, and an estimated 50% of all dogwoods in PA have been killed. Since acid deposition has been linked experimentally with disease induction, and since the disease incidence and severity are more pronounced at higher elevations where lower pH precipitation events occur, we investigated the effect of acidic foliar sprays on moiphologic changes in the foliar cuticle and trichomes (3), the initial sites of infection and foci of Discula sporulation.

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