Cytogenetics of the grasshopper Moraba scurra. 6. Spontaneous pericentric inversion.

1961 ◽  
Vol 9 (5) ◽  
pp. 784 ◽  
Author(s):  
MJD White

A single individual of Moraba scurra from Michelago, N.S.W. (out of 1730 examined cytologically) was found to be heterozygous for a pericentric inversion, which has converted the normally equal-armed AB chromosome into a J-shaped element with one limb about twice the length of the other. This is presumably a newly arisen rearrangement. It leads to five detectable cytogenetic consequences: (1) a decline in the chiasma frequency of the AB bivalent; (2) occasional failure of pairing, there being two AB univalents at first metaphase; (3) frequent orientation of the AB bivalent with its centromeres on the equator instead of in the axial plane; (4) frequent formation of a chiasma between the mutually inverted sections; (5) a stimulatory effect on the chiasma frequency of the short arm of the CD chromosome carrying the Blundell inversion. The implications of these findings for the chromosomal evolution of the approximately 180 known species of morabine grasshoppers are indicated.

2015 ◽  
Vol 146 (4) ◽  
pp. 296-305 ◽  
Author(s):  
Willam O. da Silva ◽  
Julio C. Pieczarka ◽  
Rogério V. Rossi ◽  
Horacio Schneider ◽  
Iracilda Sampaio ◽  
...  

Neacomys (Sigmodontinae) comprises 8 species mainly found in the Amazonian region. We describe 5 new karyotypes from Brazilian Amazonia: 2 cytotypes for N. paracou (2n = 56/FNa = 62-66), 1 for N. dubosti (2n = 64/FNa = 68), and 2 for Neacomys sp. (2n = 58/FNa = 64-70), with differences in the 18S rDNA. Telomeric probes did not show ITS. We provide a phylogeny using Cytb, and the analysis suggests that 2n = 56 with a high FNa is ancestral for the genus, as found in N. paracou, being retained by the ancestral forms of the other species, with an increase in 2n occurring independently in N. spinosus and N. dubosti. Alternatively, an increase in 2n may have occurred in the ancestral taxon of the other species, followed by independent 2n-reduction events in Neacomys sp. and in the ancestral species of N. tenuipes, N. guianae, N. musseri, and N. minutus. Finally, a drastic reduction event in the diploid number occurred in the ancestral species of N. musseri and N. minutus which exhibit the lowest 2n of the genus. The karyotypic variations found in both intra- and interspecific samples, associated with the molecular phylogeny, suggest a chromosomal evolution with amplification/deletion of constitutive heterochromatin and rearrangements including fusions, fissions, and pericentric inversions.


1975 ◽  
Vol 28 (1) ◽  
pp. 89 ◽  
Author(s):  
Max Kinga ◽  
Dennis King

The karyotypes have been determined of 16 of the 32 species of the genus Varanus, including animals from Africa, Israel, Malaya and Australia. A constant chromosome number of 2n = 40 was observed. The karyotype is divided into eight pairs of large chromosomes and 12 pairs of microchromosomes. A series of chromosomal rearrangements have become established in both size groups of the karyotype and are restricted to centromere shifts, probably caused by pericentric inversion. Species could be placed in one of six distinct karyotype groups which are differentiated by these rearrangements and whose grouping does not always correspond with the current taxonomy. An unusual sex chromosome system of the ZZjZW type was present in a number of the species examined.


Genome ◽  
1987 ◽  
Vol 29 (2) ◽  
pp. 292-308 ◽  
Author(s):  
B. John

The existing data on the behaviour of multiple chromosome configurations arising from single interchanges between either metacentric–telocentric or telocentric–telocentric nonhomologues in 10 species of acridid grasshoppers are compared with data from four new cases. Two of these new cases involve metacentric–telocentric exchanges but the other two, for the first time in acridids, deal with a reciprocal translocation between two nonhomologous metacentrics. The combined data are used to evaluate the factors that influence multiple orientation in this family of grasshoppers and reemphasize the importance of chiasma frequency and chiasma distribution for multiple behaviour. This conclusion is reinforced by a consideration of the known cases of chain of three multiples originating from the Robertsonian fusion of nonhomologous telocentrics in acridoids. Key words: acridid grasshoppers, multiple chromosome configurations, chiasma distribution, orientation behaviour.


Author(s):  
Iveta Dukaļska

A folk musician is an important carrier of the folk music tradition. Most of the folk musicians are talented representatives of the musicians’ craft, highly appreciated in the 20th century by the countryside society. Music making is a must at different gatherings and family celebrations (birthday parties, weddings, seasonal festivities, etc.), and this secures a high social status for the musician within the culture environment, though this also gives rise to competition among the musicians. Along with the changes within the countryside culture environment at the turn of the 20th and 21st century, also the society’s attitude towards the folk music- making tradition has changed, on the one hand viewing it as some old-fashioned activity of elderly men (the musicians), while on the other it is viewed as an important object of study for the preservation of the tradition, its renewal and reintroduction into the culture environment of the 21st century. The present study traces the development of the notion “kaktu muzikants” (literally ‘corner musician’ – a busker; self-taught, amateur musician) in Latvia from both historical and contemporary perspective, performing the culture semiotic analysis of the symbolic and mythic meanings of corner. In the Latvian culture discourse the designation “kaktu muzikants” has the following semantic aspects: 1) in the macro space – opposition of the periphery and the centre; 2) in the micro space – a special location in the inner space (the location of the musician, while playing at the dance; the „red” corner); 3) the level of professionalism, its expressive belittlement (playing without the musical score). The present study characterises the importance of the “kaktu muzikants” in the Latvian culture in 1930’s-60’s and in the present day – in the context of the traditional instrumental music. This study also uses the field-work method in order to obtain the empiric material. During field-work the data are gathered in direct interviews, deeply or partially structured interviews, where the data are obtained from the original source in the presence of the interviewer; as the result a joint view of the culture environment of the period under study was formed, along with a view of the importance and place of a country musician in the aforementioned culture environment. In the 1930’s-40’s the folk music-making tradition is mostly a local tradition of some secluded culture environment – within the boundaries of a single family, village or parish. The first skills of music making as well as those of singing are acquired within the family, where these are inherited from the members of family belonging to the older generation. Each village and parish has its musicians. Usually within a parish a single group is formed of musicians having gained recognition by the community, with this group playing at all most important events within that community – like the weddings of the better-off families and the most important dances (e.g. the dance after the remembrance event at the local cemetery). All other musicians are peripheral musicians in relation to this main group, usually playing on their own or in duos. The situations when the music is played without a written score are self-explanatory and characteristic of folk - musicians’ technique. Lacking the knowledge of musical score, the folk - musicians mainly base on the auditory or musical memory and the song’s text, the latter taking the place of notes. In cases of purely instrumental pieces playing is based on musical hearing alone. Such a technique provides good opportunities for improvisation, and reveals the creativity of the musician, his sense of music and taste. Lack of knowledge of the musical score unites people for whom music is an important part of their lives, providing them with the experience of public performance and the sense of belonging to the group of musicians, simultaneously positioning themselves as musicians of lower status compared to those graduated from some musical education institution. The division by the level of professionalism into insiders and outsiders in relation to one or the other group of musicians was especially pronounced in 1950’s-60’s, but this division has still been retained. In any music playing situation the musician has a special place within the available space allocated to him, where this space can be either inside a house (a single room), some shed or place chosen for an open air dance as a relative space. According to the data gathered during the interviews conducted in the field, the musician most frequently is seated in the corner, that corner becoming the place of honour and the centre for the musician. The designation “kaktu muzikants” is not only current in the culture environment of the 20th century countryside, but is still retained. In 1920’s-40’s quite frequently the designation “kaktu balle” (local, less important or inferior quality dance-party) is used to indicate that the event is organised by the local community (dance at some farmstead, open air dance at some grove, etc.) as compared to more official events organised and recognised by the state institutions. With this also the designation “kaktu balles muzikants” enters currency, though this has no relation to the level of professionalism of the particular musician, instead his location – the periphery. The modern designation “kaktu muzikants” is actualised particularly in the memories of the folk musicians and their life stories of the period beginning with the 1950’s. In the vocabulary of the younger generation of musicians (meaning by that the early 21st century) “kaktu muzikants” prevails as a designation of a musician aiming at understanding of the folk music-making tradition and/or the ones who have restored a music-making tradition of some of the aforementioned periods or imitate the particular instrument technique of a single individual musician.


1996 ◽  
Vol 133 (1) ◽  
pp. 91-102 ◽  
Author(s):  
B. K. Davis

AbstractA macroscopic fold formed during the fourth deformation, D4, in the Robertson River Metamorphics, north Queensland, Australia. Growth of biotite, garnet, staurolite and andalusite porphyroblasts also occurred synchronous with D4. Only biotite porphyroblasts have formed preferred alignments across the fold, and they define two dominant orientations. The more common is parallel to D4 fold axes, which is also parallel to D1 D2 and D4 intersection lineations. The other varies up to 90° from this within the D4 axial plane. Mineral elongation lineations do not reflect the extension direction of the deformation in which they formed (D4), but are a function of pre-existing anisotropics in the rock parallel to intersection lin-eations. Porphyroblast growth is inferred to be a result of microfracturing along favourably oriented linear anisotropics formed by multiple intersection of foliations, as well as parting of the the S1, and S2 foliations.


Parasitology ◽  
1912 ◽  
Vol 5 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Cecil Warburton

The identification of species of Rhipicephalus is likely to give more trouble than is the case with any other genus of Ixodidae, for while, on the one hand, there are few species which depart greatly from the general type, on the other hand the range of variation within the species is extremely great. In no genus is it so dangerous to describe a new species from a single individual, especially if the specimen be a female.


1984 ◽  
Vol 26 (3) ◽  
pp. 264-271 ◽  
Author(s):  
Kunio Kitada ◽  
Takeshi Omura

One complete asynaptic mutant, MM-19, and two partial ones, MM-4 and MM-16, of Oryza sativa L. induced by N-methyl-N-nitrosourea (MNU) were cytogenetically investigated. No chromosome pairing occurred from zygotene to pachytene and 24 univalents appeared at diakinesis and metaphase 1 in MM-19. On the other hand, a partial lack of chromosome pairing was observed from zygotene to pachytene and various numbers of univalents occurred at metaphase I in MM-4 and MM-16. The mean chiasma frequency per bivalent as well as per cell decreased to different extents in MM-4 and MM-16, and the correlation between both the amount of chromosome pairing from zygotene to pachytene and the chiasma frequency per cell at diakinesis was recognized. Judging from the development of anthers in each meiotic stage, the duration of the stage forming the synizetic knot, at which chromosome pairing took place, was longer in MM-4 and MM-16 than in the normal plant, and was in MM-19 almost as long as in the normal plant. The results of gene analyses indicate that each of the three asynaptic mutants is controlled by a recessive gene and that, at least for MM-4 and MM-16, these genes are located at different loci.Key words: asynaptic, rice, Oryza, chiasma frequency, synizesis.


Author(s):  
Ana M. Bedoya ◽  
Adam D. Leaché

AbstractSpiny lizards in the genus Sceloporus are a model system among squamate reptiles for studies of chromosomal evolution. While most pleurodont iguanians retain an ancestral karyotype formula of 2n=36 chromosomes, Sceloporus exhibits substantial karyotype variation ranging from 2n=22 to 2n=46 chromosomes. In this study, we present two annotated chromosome-scale genome assemblies for the Plateau Fence Lizard (Sceloporus tristichus) in order to facilitate research on the role of pericentric inversion polymorphisms on adaptation and speciation. Based on previous karyotype work using conventional staining, the S. tristichus genome is characterized as 2n=22 with 6 pairs of macrochromosomes and 5 pairs of microchromosomes with a large pericentric inversion polymorphism on chromosome seven that is geographically variable. We provide annotated, chromosome-scale genomes for two lizards located at opposite ends of a dynamic hybrid zone that are each fixed for different inversion polymorphisms. The assembled genomes are 1.84 to 1.87 Gb (1.72 Gb for scaffolds mapping to chromosomes) with a scaffold N50 of 267.5 Mb. Functional annotation of the genomes resulted in 65,417 annotated genes, 16,426 of which were deduced to have a function. We confirmed the presence of a 4.62 Mb pericentric inversion on chromosome seven, which contains 59 annotated coding genes with known functions. These new genomic resources provide opportunities to perform genomic scans and investigate the formation and spread of pericentric inversions in a naturally occurring hybrid zone.


2021 ◽  
Vol 26 (1) ◽  
pp. 223-239
Author(s):  
Avron Kulak

Abstract This study is dedicated to exploring the ways in which Kierkegaard provides a criterion for thinking about the principles of plurality when, in the context of distinguishing between Socrates and Christ, between different conceptions of difference—between those that support the difference of the other and those that do not—he writes that, just as no one must separate what God has joined, so no one must join what God has separated. When Kierkegaard then makes central to faith the incommensurability of single individuals, he indicates that the inviolable singularity of self and other is the one principle that can be true for all—that can be plural—since it is the one principle that is inclusive of all. In my paper I argue through Kierkegaard that the relationship between the singular and the plural embraces the paradox of absolute difference, the paradox of difference as absolute: the single individual exists only by standing in absolute relation to all others as absolute; the plural exists only insofar as it involves the commitment to the singular standard that, as absolute, preserves the difference of all.


Author(s):  
Ohad Nachtomy

Leibniz’s theory of organic emboîtement is well known, but seldom analyzed in detail. The model of embodiment Leibniz deploys is not a material one, not the kind of physical emboîtement that we find exemplified in Russian dolls, which are physically encapsulated one within the other, or the view of living things as subtle machines advanced by Descartes. This paper will examine several models of embodiment: physical, logical, expressive/representative, as well as a model of functional organization. I will conclude that the latter captures most adequately the Leibnizian view of a living being as a nested individual and the kind of embodiment it involves. What makes all these nested individuals components of a single individual is that they all follow one dominant program of action which may be seen as composed of many subprograms. But they all serve a single end (telos) that informs the developmental program of an individual.


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