scholarly journals Contribution of Cytogenetics to the Debate on the Paraphyly ofPachycondylaspp. (Hymenoptera, Formicidae, Ponerinae)

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Cléa dos Santos Ferreira Mariano ◽  
Silvia das Graças Pompolo ◽  
Janisete Gomes Silva ◽  
Jacques Hubert Charles Delabie
Keyword(s):  
Chromosome Number ◽  
Small Chromosome ◽  
The Other ◽  
Present Evidence ◽  
Other Hand ◽  
Centric Fission ◽  
Cytogenetic Studies ◽  
Pericentric Inversions ◽  
French Guyana ◽  
Acrocentric Chromosomes

We present evidence of the paraphyly of the ant genusPachycondylaresulting from our cytogenetic studies on 29 populations in 18 species from Brazil and French Guyana. It is likely that karyotypes with a large number of chromosomes and comprising mostly small acrocentric chromosomes in species within thePachycondyla stricto sensugroup resulted from a succession of centric fission events. On the other hand, karyotypes with a small chromosome number comprising mostly metacentric chromosomes are also interpreted as little derived and tend to undergo centric fission. The karyotypes of the groupNeoponeraare more heterogeneous and probably undergo successive cycles of rearrangements tending to increase the chromosome number by centric fission. Theapicalisandverenaecomplexes form two probable sister groups that evolved independently due to centric fissions (verenae) and pericentric inversions (apicalis). Our results reveal the karyotype diversity in the genus and reinforce the hypothesis on the paraphyly ofPachycondyla.

scholarly journals Transport systems for polyamines in the established renal cell line LLC-PK1. Polarized expression of an Na+-dependent transporter

1990 ◽  
Vol 265 (2) ◽  
pp. 609-612 ◽  
Author(s):  
L Van Den Bosch ◽  
H De Smedt ◽  
L Missiaen ◽  
J B Parys ◽  
R Borghgraef
Keyword(s):  
Cell Line ◽  
Renal Cell ◽  
The Other ◽  
Transport Systems ◽  
Present Evidence ◽  
Cell Monolayers ◽  
Other Hand ◽  
Basolateral Side ◽  
Renal Cell Line ◽  
Polyamine Uptake

We present evidence for the existence of an Na(+)-dependent transporter and an Na(+)-independent transporter for polyamines in LLC-PK1 cells. Both transporters could be discriminated by their sensitivity to inhibitors, particularly rho-chloromercuriphenyl sulphate and various polycationic molecules. By using cell monolayers grown on a permeable filter support, we have found that the Na(+)-dependent polyamine uptake occurred preferentially from the basolateral side. The Na(+)-independent uptake, on the other hand, occurred to the same extent from either the apical or the basolateral side.

Cytogenetic studies on Sauria (Reptilia). I. Mitotic chromosomes of the Agamidae

1988 ◽  
Vol 9 (3) ◽  
pp. 301-310 ◽  
Author(s):  
E. Solleder ◽  
M. Schmid
Keyword(s):  
Chromosome Number ◽  
Chromosome Morphology ◽  
Mitotic Chromosomes ◽  
Metaphase Chromosomes ◽  
Banding Patterns ◽  
The Family ◽  
Telocentric Chromosomes ◽  
Cytogenetic Studies ◽  
Pericentric Inversions ◽  
Dna Organization

The karotypes of nine species of the family Agamidae were analyzed with various banding techniques and conventional cytogenetic stainings. Whereas the examined species of the genera Calotes and Leiolepis exhibit conservative karyotypes, the chromosome number and chromosome morphology varies considerably within the genus Agama. This is attributed to centric fusions between telocentric chromosomes and pericentric inversions within the chromosomes. None of the species demonstrated multiple quinacrine banding patterns in the euchromatic segments of the metaphase chromosomes. This is probably due to the special DNA organization in these organisms.

scholarly journals Ploidy level and caffeine content in leaves of Coffea

1999 ◽  
Vol 56 (3) ◽  
pp. 661-663 ◽  
Author(s):  
Maria Bernadete Silvarolla ◽  
Paulo Mazzafera ◽  
Marinez Muraro Alves de Lima ◽  
Herculano Penna Medina Filho ◽  
Luiz Carlos Fazuoli
Keyword(s):  
Chromosome Number ◽  
Ploidy Level ◽  
Coffea Arabica ◽  
The Other ◽  
Caffeine Content ◽  
Other Hand ◽  
Diploid Genotype

Several species of Coffea and varieties of C. arabica differing in chromosome number had their caffeine content determined in the leaves. For Coffea arabica var. "Angustifolia", var. "Caturra" and var. "Icatu", it was observed caffeine decrease from the haploid (2n = 22) to tetraploid leaves (2n = 44). Caffeine in the tetraploid "Angustifolia" was decreased by 50% when compared to the haploid. Caffeine reduction was also observed in leaves of C. canephora var. "Kouilou" as chromosome number was increased (2n = 22 ® 2n = 44). In this case, caffeine in the leaves of the diploid genotype was close to 4 times higher than in the tetraploid. On the other hand it was observed an increase of the alkaloid when the chromosome number was doubled in the C. canephora var. "Robusta".

Et si le proto-bantu était aussi une langue … avec ses contraintes et ses déséquilibres

Diachronica ◽  
2008 ◽  
Vol 25 (1) ◽  
pp. 54-110 ◽  
Author(s):  
Gisèle Teil-Dautrey
Keyword(s):  
The Other ◽  
Present Evidence ◽  
Obligatory Contour Principle ◽  
Place Of Articulation ◽  
Phonological Structure ◽  
Other Hand ◽  
General Constraints ◽  
The One

This article aims to define the phonological structure of Proto-Bantu lexical units on the basis of frequencies of reconstructed consonant co-occurrences. Starting from the main reconstructions given in BLR3, I present evidence for the presence of unexpected frequencies indicating imbalances in two directions. Certain consonant co-occurrences have not been reconstructed, essentially consonants sharing the same place of articulation and differing by only one feature, either voicing or nasality. These “gaps” in the proto-lexicon turn out to correspond to more general constraints that tend, on the one hand, towards the differentiation of place of articulation and, on the other hand, on agreement in voicing and nasality. However, in cases where *C1 and *C2 share the same place of articulation, Proto-Bantu seems to prefer identity over similarity. In looking to establish a link between the phonotactic constraints of the mother language and those of daughter languages, the latter take different directions, either a direction identical to that of the mother language, or a divergent one. In the reconstructions, the constraints on the nasality feature show similarities to those present in contemporary languages: Ganda has extended the constraint reconstructed for alveolars to all co-occurrences between a voiced stop and a nasal with the same place of articulation. However, the constraints on voicing generated by the dissimilation rule known as Dahl’s Law go in a divergent direction. I bring support here for the view that Dahl’s Law is in fact a daughter-language innovation. Furthermore, I show that this innovation was probably induced by the imbalances of the mother language; the rule fills Proto-Bantu distributional gaps. Finally, I discuss the implications of this study for the Obligatory Contour Principle (OCP).

scholarly journals Chromosomal complements of some Atlantic Blennioidei and Gobioidei species (Perciformes)

2011 ◽  
Vol 5 ◽  
pp. 259-275 ◽  
Author(s):  
Tatiana Galvão ◽  
Luiz Bertollo ◽  
Wagner Molina
Keyword(s):  
Chromosome Number ◽  
Biological Characteristics ◽  
The Other ◽  
Remarkable Degree ◽  
Other Hand ◽  
Karyotypic Diversity ◽  
Lower Mobility ◽  
Environmental Requirements

A remarkable degree of chromosomal conservatism (2n=48, FN=48) has been identified in several families of Perciformes. However, some families exhibit greater karyotypic diversity, although there is still scant information on the Atlantic species. In addition to a review of karyotypic data available for representatives of the suborders Blennioidei and Gobioidei, we have performed chromosomal analyses on Atlantic species of the families Blenniidae, Ophioblennius trinitatis Miranda-Ribeiro, 1919 (2n=46; FN=64) and Scartella cristata (Linnaeus, 1758)(2n=48; FN=50), Labrisomidae, Labrisomus nuchipinnis (Quoy & Gaimard, 1824)(2n=48; FN=50) and Gobiidae, Bathygobius soporator (Valenciennes, 1837)(2n=48; FN=56). Besides variations in chromosome number and karyotype formulas, Ag-NOR sites, albeit unique, were located in different positions and/or chromosome pairs for the species analyzed. On the other hand, the heterochromatic pattern was more conservative, distributed predominantly in the centromeric/pericentromeric regions of the four species. Data already available for Gobiidae, Blenniidae and Labrisomidae show greater intra- and interspecific karyotypic diversification when compared to other groups of Perciformes, where higher uniformity is found for various chromosome characteristics. Evolutionary dynamism displayed by these two families is likely associated with population fractionation resulting from unique biological characteristics, such as lower mobility and/or specific environmental requirements.

CYTOGENETIC STUDIES IN THE GENUS PERSEA (LAURACEAE). I. KARYOLOGY OF SEVEN SPECIES

1975 ◽  
Vol 17 (2) ◽  
pp. 173-180 ◽  
Author(s):  
Armando Garcia V.
Keyword(s):  
Chromosome Number ◽  
Diploid Number ◽  
Persea Americana ◽  
The Other ◽  
Tetraploid Species ◽  
Chromosome Counts ◽  
Stomatal Size ◽  
World Species ◽  
The Family ◽  
Cytogenetic Studies

Chromosome number determinations were made on 137 collections of seven Persea species. Persea americana Mill., P. schiedeana Nees, and P. aff. cinerascens Rands, had a diploid number of 24 as reported earlier. The first chromosome counts for four species are reported. Persea hintonii Allen (2n = 48) is the first tetraploid species found in this genus. Persea indica (L.) Spreng. (2n = 24) is the first Old World species to have its chromosome number reported. Persea donnell-smithii Mez and P. pachypoda Nees also have the diploid number (2n = 24). One triploid (2n = 36) and one tetraploid (2n = 48) individual were found in P. americana. Based on stomatal size, their maternal plants were considered to be triploid and diploid, respectively.This is the first karyotype study in Persea and also in the family Lauraceae. The karyotype in Persea is asymmetric. The chromosomes range in size from 2.3 µm to 6.1 µm. Persea americana has one pair of satellited chromosomes, which is the largest pair, two metacentric pairs and nine submetacentric pairs. Two of the submetacentric pairs are highly heterochromatic and both are attached to the nucleolus. All the other species have karyotypes very similar to P. americana.

scholarly journals Nonlinearity in financial series: transitory or permanent?

2019 ◽  
Vol 26 (1) ◽  
Author(s):  
Christian E. Espinosa M. ◽  
Juan Gorigoitía ◽  
Carlos Maquieira
Keyword(s):  
Size Effect ◽  
Window Size ◽  
The Other ◽  
Efficient Markets ◽  
Present Evidence ◽  
Other Hand ◽  
Efficient Markets Hypothesis

In this article we present evidence that nonlinearity episodes in financial series are more permanent than transitory. At the same time, these episodes show different behaviors depending on the market analyzed, which would indicate that they are not completely synchronized. On the other hand, the size of the window for detecting nonlinear episodes has an impact on the number of nonlinear windows found, as well as the percentage of nonlinear windows with respect to the total number of windows, confirming a window size effect. The results strongly invalidate the efficient markets hypothesis and forcefully explain the incapability to predict its future values.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

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