Electrophoretic contributions to the systematics of the freshwater crayfish genus Engaeus Erichson (Decapoda : Parastacidae)

1990 ◽  
Vol 4 (3) ◽  
pp. 615 ◽  
Author(s):  
P Horwitz ◽  
M Adams ◽  
P Baverstock
Keyword(s):  
Allelic Variation ◽  
Threshold Level ◽  
Sympatric Species ◽  
Biological Species ◽  
Genetic Differences ◽  
Freshwater Crayfish ◽  
Electrophoretic Data ◽  
Allelic Differences ◽  
Low Levels ◽  
Group Relationships

As part of an examination into the systematics of the freshwater crayfish genus Engaeus, an electrophoretic evaluation of specimens from a large number of collecting sites has been undertaken. From a total of 76 sample sets, a minimum of 30 distinct biological species have been delineated. Strong evidence from sites of both sympatry and allopatry suggests some further delineations of species but these must await additional discriminatory information. Sympatric species were detected on 11 separate occasions. In each case, fixed allelic differences were found, indicating an absence of interbreeding between each sympatric pair. Allopatric species were delineated where genetic differences between populations exceeded a threshold level determined from observed genetic differences between sympatric Engaeus species and between other (mainly decapod) species in the literature. The results of this analysis have confirmed low levels of heterozygosity in Engaeus species. Frequent isoIation of small populations of Engaeus species, and consequent loss of allelic variation, is suggested as a possible cause of these low levels. Some species have shown variation of allelic frequencies over their geographical range and, in some cases, this variation could be interpreted as showing clinal properties. Finally, the electrophoretic data have been interpreted to produce some information regarding the phylogenetic affinities of delineated species. Several groups of species were found which shared closer intra-group relationships than they did to the other species of Engaeus.

scholarly journals Interfertility between Armillaria cepistipes and A. sinapina

2005 ◽  
Vol 77 (2) ◽  
pp. 67-74 ◽  
Author(s):  
J.A. Bérubé ◽  
M. Dessureault ◽  
S. Berthelay ◽  
J.-J. Guillaumin
Keyword(s):  
North America ◽  
Sympatric Species ◽  
Biological Species ◽  
Malt Extract ◽  
Low Level ◽  
Different Types ◽  
Genetic Barriers ◽  
Low Levels ◽  
Incubation Temperatures ◽  
Armillaria Cepistipes

European strains of Armillaria cepistipes were reported to be interfertile with strains from three American Armillaria species known as North American Biological Species (NABS) V (A sinapina), NABS X and NABS XI. Such interfertility between species raises some doubts about using different Latin binomials for species capable of mating. This interfertility was reinvestigated by mating 24 haploid isolates of European A cepistipes with 23 isolates of A sinapinafrom North America and Asia. Individual pairings were independently performed at least once at Universite Laval, Canada and at INRA Clermont-Ferrand, France. From the 420 interspecific pairings performed at Laval, two were positive and seven were ambiguous for a total of 2.1% of all the pairings. From the 506 pairings made at Clermont-Ferrand, 10 were positive and 24 were ambiguous for a total of 6.7%. The differences in the pairing results may be explained by incubation temperatures, and the different types and concentrations of malt extract used at each laboratory. The low levels of interfertility found between A. cepistipes and A. sinapina may result from the absence of genetic barriers that are usually present between sympatric species. This low level of interfertility reflects differences in morphology, distribution, and habitat for these two species of Armillaria and this supports the retention of different species denominations.

GENETIC VARIATION IN RARE AND WIDESPREAD LOMATIUM SPECIES (APIACEAE): A COMPARISON OF AFLP AND SSCP DATA

2001 ◽  
Vol 58 (2) ◽  
pp. 347-356 ◽  
Author(s):  
M. A. GITZENDANNER ◽  
P. S. SOLTIS
Keyword(s):  
Rare Species ◽  
Nucleotide Diversity ◽  
Nuclear Dna ◽  
Allelic Variation ◽  
Plant Conservation ◽  
Single Copy ◽  
Small Populations ◽  
Nucleotide Polymorphisms ◽  
Widespread Species ◽  
Low Levels

Plant conservation genetics has been hampered by a lack of markers for studies of levels and patterns of variation in rare species. We investigated the levels of variation in several rare and widespread species of the western North American genus Lomatium Raf. (Apiaceae) using two relatively new molecular markers: AFLPs and single-strand conformation polymorphisms (SSCPs). For each species, approximately 150 AFLP loci have been scored, yielding estimates of species-level percent polymorphic loci in rare species ranging from near zero to over 80%. Levels of AFLP diversity were similar in two of the rare species, L. bradshawii (Rose ex Mathias) Mathas & Constance and L. ochocense Helliwell & Constance, and the widespread species. The third rare species, L. cookii Kagan, which has small populations, has low levels of diversity based on AFLPs. We also examined nucleotide diversity at the single-copy nuclear-DNA locus glyceraldehyde 3-phosphate dehydrogenase (Gap-C). PCR-amplified segments were analysed for allelic variation using SSCPs, and intrapopulational nucleotide polymorphisms were identified in both L. bradshawii and L. cookii. In the 211bp segment of Gap-C analysed, five nucleotide sites were segregating within populations of L. bradshawii and two in L. cookii.

scholarly journals Permethrin Resistance Status and Associated Mechanisms in Aedes albopictus (Diptera: Culicidae) From Chiapas, Mexico

2020 ◽  
Author(s):  
Ashley J Janich ◽  
Karla Saavedra-Rodriguez ◽  
Farah Z Vera-Maloof ◽  
Rebekah C Kading ◽  
Américo D Rodríguez ◽  
...  
Keyword(s):  
Aedes Albopictus ◽  
Sympatric Species ◽  
Resistance Mutations ◽  
Cytochrome P450 Activity ◽  
Knockdown Effect ◽  
Low Toxicity ◽  
Continued Use ◽  
Low Levels ◽  
Increased Activity ◽  
P450 Activity

Abstract There are major public health concerns regarding the spread of mosquito-borne diseases such as dengue, Zika, and chikungunya, which are mainly controlled by using insecticides against the vectors, Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse). Pyrethroids are the primary class of insecticides used for vector control, due to their rapid knockdown effect and low toxicity to vertebrates. Unfortunately, continued use of pyrethroids has led to widespread insecticide resistance in Ae. aegypti; however, we lack information for Ae. albopictus—a sympatric species in Chiapas since 2002. In this study, we evaluated the permethrin resistance status of Ae. albopictus collected from Mexico and Texas. We also selected for permethrin resistance in the laboratory and investigated the potential mechanisms conferring resistance in this species. Knockdown resistance mutations, specifically F1534C, in the voltage-gated sodium channel gene, and increased activity of detoxifying enzymes were evaluated. Low levels of permethrin resistance (<2.4-fold) were observed in our field populations of Ae. albopictus and the F1534C mutation was not detected in any of the sites. Low levels of resistance were also observed in the artificially selected strain. There was significantly higher cytochrome P450 activity in our permethrin-selected and nonselected strains from Mexico compared to the control strain. Our results suggest the Ae. albopictus sampled from 2016 are mostly susceptible to pyrethroids. These results contrast with the high levels of permethrin resistance (>58-fold) found in Ae. aegypti from the same sites in Mexico. This research indicates the importance of continued monitoring of Ae. albopictus populations to prevent resistance from developing in the future.

scholarly journals Division of Giardia isolates from humans into two genetically distinct assemblages by electrophoretic analysis of enzymes encoded at 27 loci and comparison with Giardia muris

Parasitology ◽  
1995 ◽  
Vol 111 (1) ◽  
pp. 11-17 ◽  
Author(s):  
G. Mayrhofer ◽  
R. H. Andrews ◽  
P. L. Ey ◽  
N. B. Chilton
Keyword(s):  
Homo Sapiens ◽  
Single Species ◽  
Electrophoretic Analysis ◽  
Genetic Differences ◽  
Giardia Intestinalis ◽  
Evolutionary Relationships ◽  
Enzyme Loci ◽  
Allelic Differences ◽  
Animal Hosts ◽  
Giardia Muris

SUMMARYGiardia that infect humans are known to be heterogeneous but they are assigned currently to a single species, Giardia intestinalis (syn. G. lamblia). The genetic differences that exist within G. intestinalis have not yet been assessed quantitatively and neither have they been compared in magnitude with those that exist between G. intestinalis and species that are morphologically similar (G. duodenalis) or morphologically distinct (e.g. G. muris). In this study, 60 Australian isolates of G. intestinalis were analysed electrophoretically at 27 enzyme loci and compared with G. muris and a feline isolate of G. duodenalis. Isolates of G. intestinalis were distinct genetically from both G. muris (approximately 80% fixed allelic differences) and the feline G. duodenalis isolate (approximately 75% fixed allelic differences). The G. intestinalis isolates were extremely heterogeneous but they fell into 2 major genetic assemblages, separated by fixed allelic differences at approximately 60% of loci examined. The magnitude of the genetic differences between the G. intestinalis assemblages approached the level that distinguished the G. duodenalis isolate from the morphologically distinct G. muris. This raises important questions about the evolutionary relationships of the assemblages with Homo sapiens, the possibility of ancient or contemporary transmission from animal hosts to humans and the biogeographical origins of the two clusters.

Morphological and biochemical variation among common reed (Phragmites australis) populations in northwest Poland

2009 ◽  
Vol 38 (2) ◽  
Author(s):  
Maria Drapikowska ◽  
Maria Krzakowa
Keyword(s):  
Gene Flow ◽  
Phragmites Australis ◽  
Plant Material ◽  
Common Reed ◽  
Genetic Differences ◽  
Electrophoretic Data ◽  
Biochemical Variation ◽  
Panicle Traits

Morphological and biochemical variation among common reed (Plant material from 42 common reed populations originating from various lakes and ponds in northwest Poland were investigated with respect to eight panicle traits and three peroxidase loci that were detected with electrophoresis. Genetic differences between populations were estimated based on allozyme frequencies. Electrophoretic data indicated that some populations contain an excess of heterozygotes, pointing to extensive gene flow, which is typical of panmictic, open-pollinated populations.

Electrophoretic divergence of Myotis leibii and Myotis ciliolabrum (Chiroptera: Vespertilionidae)

1987 ◽  
Vol 65 (7) ◽  
pp. 1857-1860 ◽  
Author(s):  
Robert M. Herd
Keyword(s):  
Distinct Species ◽  
Data Support ◽  
Electrophoretic Data ◽  
Allelic Differences ◽  
Myotis Leibii

Myotis ciliolabrum has recently been recognised as a species distinct from Myotis leibii. Electrophoretic divergence between the two species exceeds that of subspecies of other bats and is similar to that found between other species. Fixed allelic differences at two loci suggested that no introgression occurs. The electrophoretic data support the conclusion that M. ciliolabrum and M. leibii are distinct species.

scholarly journals ASSESSMENT OF VARIABILITY WITHIN ELECTROMORPHS OF ALCOHOL DEHYDROGENASE IN DROSOPHILA MELANOGASTER

Genetics ◽  
1980 ◽  
Vol 95 (2) ◽  
pp. 467-475
Author(s):  
Martin Kreitman
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Analysis ◽  
Alcohol Dehydrogenase ◽  
Natural Population ◽  
Allelic Variation ◽  
Structural Locus ◽  
Standard Methods ◽  
Electrophoretic Mobilities ◽  
Allelic Variability ◽  
Allelic Differences

ABSTRACT Ninety-six isochromosomal lines of Drosophila melanogaster from a natural population were screened electrophoretically for unusual mobility variants at the alcohol dehydrogenase locus, using a total of eight conditions of acrylamide electrophoresis. No additional mobility variation was found among the 50 "slow" and 46 "fast" mobility lines beyond that detected by standard methods of electrophoresis. However, two thermostability variants recovered by R. MILKMAN from a natural population, whose electrophoretic mobilities were previously thought to be indistinguishable from those of "standard" alleles, are distinguishable from the standard elcctromorphs by these procedures. These results suggest that the Adhlocus, although polymorphic, does not harbor substantial amounts of "hidden" allelic variability. This study also reports the appearance of substantial mobility variation among isogenic lines that can be induced under specific conditions of sample preparation involving the pretreatment of samples with NAD and acetone. However, genetic analysis demonstrates that this variability cannot be attributed to allelic differences at the structural locus, but instead appears to be dependent upon the concentration of the enzyme in a sample. These results are discussed in relation to the distribution of allelic variation at other enzyme loci.

scholarly journals Behaviour of Flanking Markers in Allelic Crosses

1966 ◽  
Vol 19 (6) ◽  
pp. 1047 ◽  
Author(s):  
DG Catcheside
Keyword(s):  
Fine Structure ◽  
Genetic Recombination ◽  
Genetic Differences ◽  
Quantitative Theory ◽  
Allelic Differences

The principles of analysis of the distributions of flanking markers amongst prototrophic recombinants arising from allelic auxotrophic differences are discussed. Considerable variations occur in the parameters which may be measured and also in the degree of agreement of criteria used to place allelic differences in order in fine structure maps. At least some of these variations appear likely to depend upon genetic differences affecting the mechanisms which result in genetic recombination and the mechanisms which control their activity. An approach to a quantitative theory of the distribution of flanking markers is suggested.

scholarly journals Esterase polymorphism in remanant populations of Aspidosperma polyneuron Müll.Arg. (Apocynaceae)

2004 ◽  
Vol 28 (5) ◽  
pp. 625-631
Author(s):  
Vanda Marilza de Carvalho ◽  
Maria de Fátima Pires da Silva Machado
Keyword(s):  
Genetic Variation ◽  
Endangered Species ◽  
Allelic Variation ◽  
Northern Population ◽  
Endangered Tree ◽  
Endangered Tree Species ◽  
Esterase Polymorphism ◽  
Hardy Weinberg Equilibrium ◽  
Low Levels ◽  
Is Value

The population genetic structure of the endangered tree species Aspidosperma polyneuron Mull.Arg. (Apocynaceae) was reported based on analysis of esterase polymorphism in two remanant populations. Allelic variation was detected at three isoesterase loci (Est-3, Est-9, and Est-10). The proportion of polymorphic loci for both populations was 30% and deviation from Hardy-Weinberg equilibrium was observed for the Est-3 locus observed in the northern population. Segregation distortion and the lower level of observed and expected heterozygosity in this population were attributed to founder genotype. The high genetic identity values for northern and northwestern populations are in accordance with the low levels of interpopulation genetic divergence demonstrated by the F(ST) (0.03) value. The F(IS) value (0.23) indicated moderate levels of inbreeding. A. polyneuron can be indicated as an example of endangered species suggesting high genetic variation in contrast to the low genetic variation reported for endangered species. The esterase isozymes may be a good genetic marker for studies of natural A. polyneuron populations.

scholarly journals Distinct effects of thrombopoietin depending on a threshold level of activated Mpl in BaF-3 cells

2002 ◽  
Vol 115 (11) ◽  
pp. 2329-2337
Author(s):  
Gaël A. Millot ◽  
William Vainchenker ◽  
Dominique Duménil ◽  
Fédor Svinarchuk
Keyword(s):  
Signaling Pathways ◽  
Intracellular Signaling ◽  
Kinase Inhibitors ◽  
Critical Role ◽  
Threshold Level ◽  
Pi3k Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Activation Level ◽  
Low Levels ◽  
In Cells

Thrombopoietin (TPO) plays a critical role in megakaryopoiesis through binding to its receptor Mpl. This involves activation of various intracellular signaling pathways, including phosphoinositide 3-kinase (PI3K) and the mitogen-activated protein kinase (MAPK) pathways. Their precise role in TPO-mediated proliferation, survival and differentiation is not fully understood. In the present study, we show that TPO induces different biological responses in Mpl-transduced BaF-3 cells, depending on the cell surface density of Mpl and the resulting activation level of signaling pathways. TPO mediates cell proliferation in cells expressing high levels of Mpl but only mediates survival without proliferation in cells expressing low levels of the receptor. By using the kinase inhibitors PD98059 and LY294002,we further showed that the activation level of the PI3K and MAPK p42/44 pathways is a determining factor for the proliferative effect. In cells expressing low levels of Mpl, the survival effect was strongly dependent on the activation level of the PI3K/AKT, but not the MAPK p42/44 pathway. Moreover, this effect was correlated with the phosphorylation level of BAD but not with the expression level of Bcl-XL. However, PI3K pathway inhibition did not increase apoptosis when BaF-3 cells proliferated in response to TPO, indicating a compensating mechanism from other Mpl signaling pathways in this case.

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