A REANALYSIS OF DIPLOID MALE FREQUENCIES IN EUGLOSSINE BEES (HYMENOPTERA: APIDAE)

A dioecious grass Sohnsia filifolia (Fourn.) Airy Shaw (Syn. Calamochloa filifolia Fourn.) from Mexico has been found to have 2n = 20 chromosomes in both male and female plants. The staminate plants have one chromosome much longer than the other chromosomes of the complement. One pistillate plant was found to have 30 chromosomes, among which the largest chromosome is quite similar to the largest component of the diploid male plant. The longest chromosome has been designated as the Y chromosome. An XY-mechanism of the Drosophilia type has been suggested for the sex determination system in this species. One small supernumerary chromosome was observed in the microsporocytes of some male plants, but was absent in roots.

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Nectar-foraging behavior of Euglossine bees (Hymenoptera: Apidae) in urban areas

Apidologie ◽

10.1051/apido:2008023 ◽

2008 ◽

Vol 39 (4) ◽

pp. 410-418 ◽

Cited By ~ 33

Author(s):

Margarita María López-Uribe ◽

Cintia Akemi Oi ◽

Marco Antonio Del Lama

Keyword(s):

Foraging Behavior ◽

Urban Areas ◽

Euglossine Bees ◽

Nectar Foraging

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Evidence of male germ cell redifferentiation into female germ cells in planarian regeneration

Development ◽

10.1242/dev.70.1.29 ◽

1982 ◽

Vol 70 (1) ◽

pp. 29-36

Author(s):

V. Gremigni ◽

M. Nigro ◽

I. Puccinelli

Keyword(s):

Germ Cells ◽

Somatic Cells ◽

The Body ◽

Diploid Male ◽

Female Gonad ◽

Anterior Portion ◽

Male Germ Cells ◽

Blastema Formation ◽

Planarian Regeneration ◽

Undifferentiated Cells

The source and fate of blastema cells are important and still unresolved problems in planarian regeneration. In the present investigation we have attempted to obtain new evidence of cell dedifferentiation-redifferentiation by using a polyploid biotype of Dugesia lugubris s.1. This biotype is provided with a natural karyological marker which allows the discrimination of triploid embryonic and somatic cells from diploid male germ cells and from hexaploid female germ cells. Thanks to this cell mosaic we previously demonstrated that male germ cells take part in blastema formation and are then capable of redifferentiating into somatic cells. In the present investigation sexually mature specimens were transected behind the ovaries and the posterior stumps containing testes were allowed to regenerate the anterior portion of the body. Along with the usual hexaploid oocytes, a small percentage (3.2%) of tetraploid oocytes were produced from regenerated specimens provided with new ovaries. By contrast only hexaploid oocytes were produced from control untransected specimens. The tetraploid oocytes are interpreted as original diploid male germ cells which following the transection take part in blastema formation and then during regeneration redifferentiate into female germ cells thus doubling their chromosome number as usual for undifferentiated cells entering the female gonad in this biotype.

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