Abstract
A spontaneous structural heterozygote originated from a centric fusion involving two acrocentric autosomes (M5 and S8) in a male Chorthippus jucundus (2n=16+X) was tested for the effects on chiasmata characteristics and the role that these could play in metaphase-I orientation of the trivalent. Results show non-existence of inter- or intra-chromosomal effects on chiasma frequency when compared with standard individuals, and displacement of the single chiasma on the S8 to a distal position while no significant change is appreciated in the M5 chiasma distribution. The presence of two chiasmata on the M5 and one on the S8 always induces a linear orientation of the trivalent. However, when two chiasmata are present (one on each chromosome) and independently of their location on each arm (proximal, interstitial of distal) any of the possible orientations (linear or convergent) can be attained. The frequency of linear orientation is higher than that expected at random in the resulting trivalent during metaphase-I and the rate of reorientation is very low.
The meitotic behaviour of such a trivalent is discussed taking into account the already mentioned aspects together with the size of the fused element.
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García de la Vega C., López-Fernández C., Gosálvez J. & Rufas J. S., 1982. Cytogenetic studies on Chorthippus jucundus (Fisch.) (Orthoptera). II. Heterochromatin variation and NOR localization. Cytobios 34: 7–14.
Gosálvez J., García de la Vega C., López-Fernández C. & Rufas J. S., 1981. Cytogenetic studies on Chorthippus jucundus (Fisch.) (Orthoptera). I. Heterochromatic segments in Spanish wild population. Brotéria-Gen. 77: 41–50.
Gosálvez J., López-Fernández C. & García Lafuente R., 1982. A spontaneous translocation heterozygote involving centromere regions in Gomphocerus sibiricus (Orthoptera: Acrididae). Chromosoma 86: 49–57.
Hewitt G. M., 1979. Animal Cytogenetics. 3. Insecta 1. Orthoptera. Borntraeger, Berlin-Stuttgart, 160 pp.
John B., 1973. The cytogenetic system of grasshoppers and locusts. II. The origin and evolution of supernumerary segments. Chromosoma 44: 123–146.
Kayano H. & Nakamura K., 1960. Chiasma studies in structural hybrids. V. Heterozygotes for a centric fusion and for a translocation in Acrida lata. Cytologia 25: 476–480.
López-Fernández C. & Gosálvez J., 1981. Differential staining of a heterochromatic zone in Arcyptera fuscs (Orthoptera). Experientia 37: 240.
Parker J. S., Palmer R. W., Whitehorn M. A. F. & Edgar L. A., 1982. Chiasma frequency effects of structural chromosome change. Chromosoma 85: 673–686.
Southern D. I. 1967. Spontaneous chromosome mutations in truxaline grasshoppers. Chromosoma 22: 241–257.
Sybenga J., 1975. Meiotic configurations. Monogr. theor. appl. Genet. Vol. 1. Berlin Heidelberg New-York: Springer.
White M. J. D., 1956. Adaptative chromosomal polymorphism in an australian grasshopper. Evolution 10: 298–313.
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López-Fernández, C., Rufas, J.S., García de la Vega, C. et al. Cytogenetic studies on Chorthippus jucundus (Fisch.) (Orthoptera) III. The meiotic consequences of a spontaneous centric fusion. Genetica 63, 3–7 (1984). https://doi.org/10.1007/BF00137458
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DOI: https://doi.org/10.1007/BF00137458