Myrmecia pilosula , an Ant with Only One Pair of Chromosomes

Abstract

A new sibling species of the primitive Australian ant Myrmecia pilosula has a chromosome number of n = 1. C-banding techniques confirm that the two chromosomes of workers are homologous. Males are haploid, as in other Hymenoptera, and their somatic cells contain only a single chromosome. This new species is potentially of great importance in both laboratory and field studies on gene organization.

Within-host Evolution of Segments Ratio for the Tripartite Genome ofAlfalfa Mosaic Virus

“…Regardless of the initial conditions (included in the plot to illustrate the coordinates of the different starting points), after infection all RNA populations tend to a rather limited region of the possible space of solutions, which contains the SGF total ratio. Table 1B shows the results from the MANOVA analysis run for the RNA frequencies estimated from encapsidated RNAs fitted to equation (1). The only difference with the results just reported for the total RNAs is the lack of differences among replica plants (term P(M) in equation (1); P = 0.248).…”

“…1D) and thus is expected to be the relevant figure in terms of horizontal virus transmission. Table 1A shows the results of the multivariate analysis of variance (MANOVA) analysis for the RNA frequencies from total RNA extractions fitted to equation (1). This equation, described in detail in the Methods section, relates all three experimental factors with the observed RNA segments frequencies: the RNA mixtures inoculated (M), the replicate plants inoculated with each RNA mixture (P) and the different tissues sampled (S).…”

“…In this case, factor E i represents the plant species (i ∈ {C. annuum, C. pepo, M. sativa, N. benthamiana, N. tabacum} and all other factors are as described for equation (1).…”

“…Genome segmentation is a ubiquitous feature of eukaryotes, with nuclear chromosome numbers covering an enormous range: from 2n to 630n 1,2 . In contrast, bacteria and archaea typically have a single chromosome 3 .…”

Notes on the Remarkable Karyology of the Primitive Ant Nothomyrmecia Macrops, and of the Related Genus Myrmecia (Hymenoptera: Formicidae)

“…It is from an undescribed, chromosomally polymorphic, southeastern mainland Australian species first reported by Crosland and Crozier (1986), and referred to in our studies as Myrmecia (pilosula)n--1, which is known from detailed analysis to have 2n=2, 3 or 4; n--1 or 2 (Imai and Taylor, 1989). It is a sibling relative of the "jack jumper" Myrmecia pilosula Smith, the nominate member of the M. pilosula species complex, which currently includes an estimated 6 morphologically closely similar but karyologically diverse putative species (with known chromosome counts of 2n=2-4, 8, 9, 10, 15 and 17-32).…”