Orientation of nonrandomly segregating sex chromosomes in spermatocytes of the flea beetle, Alagoasa bicolor L.

Chromosoma ◽  
2001 ◽  
Vol 110 (1) ◽  
pp. 32-38 ◽  
Author(s):  
B.L. Green-Marroquin ◽  
H. Kupfer ◽  
N. Virkki ◽  
D.A. Wise
Keyword(s):  
Sex Chromosomes ◽  
Flea Beetle

The pattern of sex chromosome kinetochore phosphorylation during nonrandom segregation in a flea beetle

2000 ◽  
Vol 78 (2) ◽  
pp. 93-98
Author(s):  
Holly Kupfer ◽  
Dwayne Wise
Keyword(s):  
Key Words ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Flea Beetle ◽  
Beetle Species ◽  
Kinetochore Protein ◽  
Linear Configuration ◽  
Meiosis I ◽  
Metaphase I

In the flea beetle species, Alagoasa bicolor, males have two sex chromosomes, X and Y, each of which is larger than the rest of the genome combined. These large sex chromosomes do not pair at meiosis I, and are therefore not joined at metaphase I. Nevertheless, they always segregate from each other at anaphase I. As prometaphase I progresses, the unpaired X and Y undergo reorientation from a parallel to a linear configuration. Using 3F3/2, an antibody that detects the level of phosphorylation of a kinetochore protein or proteins, we have determined that this reorientation is not accompanied by a change in the level of phosphorylation of the kinetochores of either X or Y. This implies that: i) either the reorientation does not involve the loss or gain of kinetochore microtubules, or ii) if such loss or gain occurs, it does not effect a change in the tension placed on the nonrandomly segregating kinetochores, or iii) the sex chromosomes, as in some other species, have lost the ability to sense kinetochore tension changes. Evolution of nonrandom segregation may necessitate the inability of the participating chromosomes to affect the metaphase checkpoint. Key words: nonrandom segregation, sex chromosomes, kinetochores.

Behavior of sex chromosomes, autosomes, and the spindle during nonrandom segregation in a flea beetle

Genome ◽  
2000 ◽  
Vol 43 (3) ◽  
pp. 521-527
Author(s):  
Holly Kupfer ◽  
Dwayne Wise
Keyword(s):  
Sex Ratio ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Flea Beetle ◽  
Next Generation ◽  
Daughter Cells ◽  
Spindle Poles ◽  
Y Chromosomes ◽  
Linear Configuration ◽  
Spindle Elongation

We have analyzed autosome, sex chromosome, and spindle behavior in spermatocytes of the flea beetle, Alagoasa bicolor. In this species, males have very large X and Y chromosomes, which, although they are never physically connected, always segregate to opposite spindle poles at anaphase I, thus preserving the sex ratio in the next generation. We find that the sex chromosomes are partitioned to a peripheral spindle domain early in prometaphase I and that their segregation can be accounted for mainly by their reorientation from the parallel to the linear configuration, and little by chromosome-to-pole movement. Further, the behavior of the autosomes and that of the sex chromosomes seem to have little to do with each other. Spindle elongation is minimal; barely segregating the large sex chromosomes into the daughter cells at telophase I.Key words: nonrandom segregation, sex chromosomes, kinetochores.

Herbicides compromise biological control of ragwort

2002 ◽  
pp. 147-152
Author(s):  
K. Betteridge ◽  
D. Costall
Keyword(s):  
Biological Control ◽  
Pyrrolizidine Alkaloids ◽  
Animal Health ◽  
Flea Beetle ◽  
Dairy Farm ◽  
Senecio Jacobaea ◽  
Longitarsus Jacobaeae ◽  
High Ester ◽  
Low Levels

In spite of ragwort flea beetle (RFB) being present on a Dannevirke dairy farm, pastures were sprayed each winter to reduce ragwort density and limit the risk of ragwort poisoning of stock. The trial on this farm from June 1999 - October 2001, aimed to determine whether herbicide (H) impacted on RFB and how H and RFB each impacted on ragwort growth and persistence. RFBfree areas were created by spraying with insecticide (I). Effects of ragwort on animal health are also reported. High ester 2,4-D (H) boom-sprayed once only, in June 1999, killed most ragwort plants and reduced RFB larvae densities to low levels before the plants died. Once new ragwort established in treatment H, the plants became infested with RFB larvae. RFB larvae were suppressed by I resulting in ragwort density declining more slowly than in treatments where RFB were not suppressed. Insecticide treatments were stopped after 15 months and, at 24 months, ragwort could not be found within the trial area. Ragwort control was attributed to the cessation of herbicide spraying allowing the RFB population to reach a sufficient density to kill both small and large ragwort plants. Sub-clinical ragwort poisoning was found in livers of culled cows that had grazed on ragwort-dense pastures. Keywords: animal health, biological control, Longitarsus jacobaeae, pyrrolizidine alkaloids, ragwort, ragwort flea beetle, Senecio jacobaea

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