The thermosensitive mutant sm19 of Paramecium tetraurelia undergoes a progressive reduction in cell length and basal body number over successive divisions at the nonpermissive temperature of 35°C. In spite of these defects, sin19 cells retain the same generation time as wild-type cells at 35°C. Cytological observations at both electron and light microscopy levels reveal no other perturbation th...

Chloroplast (trnL–F and rbcL) sequences were used to reconstruct the phylogeny of Geraniaceae and Hypseocharitaceae. According to these data Hypseocharitaceae and Geraniaceae are monophyletic. Pelargonium and Monsonia are sisters to the largest clade of Geraniaceae, formed by Geranium, Erodium and California. According to molecular dating and dispersal-vicariance analysis, the split of the stem...

IN the late 1930s when Tracy Sonneborn was in graduate school and just starting his work on the genetics of protozoa, classical studies on genetics were almost finished. The second edition of Principles of Genetics by E. W. Sinnott and L. C. Dunn (1932) that appeared in that period was quite sophisticated, containing a good account of chromosome theory, segregation ratios produced by complex ge...

S In Paramecium p r i m a u r e l i a , the macronudear gene encoding the G surface protein ia located near a telomere. In th is study, mul t ip le copies of t h i s te lomere have been i s o l a t e d and the subte lomer ic and t e l o m e r i c regions of some of them have been sequenced. The te loroer ic sequences consist of tandem repeats of the hexanucleotidea C»A2 or C3A3. We show that th...

Most species of flowering plants rely on animal pollinators for effective mating (Ollerton et al., 2011), often interacting with diverse communities floral visitors 2007; Waser 1996). However, many commonly receive incompatible pollen, self-pollen or pollen from closely related individuals, thus influencing the quality that reaches target (Aizen & Harder, Ashman 2004). Such reductions in plant ...

Understanding the natural mating behavior (selfor cross-pollination) in watermelon is important to the design of a suitable breeding strategy. The objective of this study was to measure the rate of selfand cross-pollination in watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] using the dominant gene Sp (Spotted leaves and fruit) as a marker. The experiment consisted of two studies and was...

Artificial hybridizations of Schiedea and Alsinidendron (Caryophyllaceae: Alsinoideae), genera endemic to the Hawaiian Islands, were used to study the effects of phylogenetic relationship, genetic divergence, breeding system, and population size on the ability of species to cross and produce fertile F1 hybrids. Using 17 taxa, all crosses attempted produced vigorous F1 hybrids, although pollen f...