Oka: Behind the Barricades: Kanehsatake: 270 Years of Resistance: Spudwrench: Kahnawake Man: My Name is Kahentiiosta: Acts of Defiance

Oka: Behind the Barricades. 1998. 312 minutes. For more information contact the National Film Board of Canada, 3155 Côte de Lisse Rd., St. Laurent, Quebec H4N 2N4. Series of four videos:
Kanehsatake: 270 Years of Resistance. 1993. 120 minutes. Directed by Alanis Obomsawin .
Spudwrench: Kahnawake Man. 1997. 58 minutes. Directed by Alanis Obomsawin .
My Name is Kahentiiosta. 1995. 30 minutes. Directed by Alanis Obomsawin .
Acts of Defiance. 1992. 104 minutes. Directed by Alec MacLeod .     

Ultrastructure of the spermatozoon of Megaselia scalaris Loew (Diptera:Brachycera:Cyclorrhapha:Phoridea:Phoridae)

When viewed by scanning electron microscopy (SEM), the spermatozoon of the phorid dipteran Megaselia scalaris appears threadlike, lacking distinct head and tail areas. These areas can be observed, however, in appropriately stained material. Measurements of Feulgen-stained material reveal average lengths of the head, tail, and total cell of 18.7, 128.7, and 147.4 μm, respectively. When tested for sulfhydryl and disulfide groups, the head displays only disulfide groups. Transmission electron microscopy (TEM) reveals 12 different regions: three (1–3) in the head, four (9–12) in the tail, and five (4–8) in a short zone of overlap between the head and tail. Most of the cell lies in regions 9 and 11 of the tail and 3 of the head, accounting for, respectively, 37.3%, 45.7%, and 11.2% of the total length. A tubelike acrosome indents the anterior end of the nucleus. The tail originates asymmetrically in relation to the long axis of the cell as a peglike structure associated with the dorsolateral region of the nucleus. No centriole is visible, and the nucleus has a notched appearance in longitudinal sections. Two mitochondrial derivatives and an axoneme displaying a 9+9+2 microtubule configuration and ATPase activity extend throughout most of the tail. In regions 9 and 10, an asymmetrically arranged accessory body is also present. Features having possible taxonomic utility include the asymmetrically arranged accessory body, the size and shape of the acrosome, and the notched appearance of the nucleus. The present report is apparently the first to describe the spermatozoon of a cyclorrhaphous dipteran which is not a member of the Schizophora.     

Quadruplexes of human telomere DNA analogs designed to contain G:A:G:A,G:G:A:A,and A:A:A:A tetrads

Replacement of two to four guanines by adenines in the human telomere DNA repeat dG₃(TTAG₃)₃ did not hinder the formation of quadruplexes if the substitutions took place in the terminal tetrad bridged by the diagonal loop of the intramolecular antiparallel three‐tetrad scaffold, as proved by CD and PAGE in both Na⁺ and K⁺ solutions. Thermodynamic data showed that, in Na⁺ solution, the dG₃(TTAG₃)₃ quadruplex was destabilized, the least by the two G:A:G:A tetrads, the most by the G:G:A:A tetrad in which the adenosines replaced syn‐guanosines. In physiological K⁺ solution, the highest destabilization was caused by the 4A tetrad. In K⁺, only the unmodified dG₃(TTAG₃)₃ quadruplex rearranged into a K⁺‐dependent quadruplex form, none of the multiple adenine‐modified structures did so. This may imply biological consequences for nonrepaired A‐for‐G mutations. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 880–886, 2010.     

Detection of DNA damage by use of Escherichia coli carrying recA'::lux, uvrA'::lux, or alkA'::lux reporter plasmids.

Plasmids were constructed in which DNA damage-inducible promoters recA, uvrA, and alkA from Escherichia coli were fused to the Vibrio fischeri luxCDABE operon. Introduction of these plasmids into E. coli allowed the detection of a dose-dependent response to DNA-damaging agents, such as mitomycin and UV irradiation. Bioluminescence was measured in real time over extended periods. The fusion of the recA promoter to luxCDABE showed the most dramatic and sensitive responses. lexA dependence of the bioluminescent SOS response was demonstrated, confirming that this biosensor's reports were transmitted by the expected regulatory circuitry. Comparisons were made between luxCDABE and lacZ fusions to each promoter. It is suggested that the lux biosensors may have use in monitoring chemical, physical, and genotoxic agents as well as in further characterizing the mechanisms of DNA repair.     

Hormone interactions and regulation of PsPK2::GUS compared with DR5::GUS and PID::GUS in Arabidopsis thaliana

The putative pea PINOID homolog, PsPK2, is expressed in all growing plant parts and is positively regulated by auxin, gibberellin, and cytokinin. Here, we studied hormonal regulation of PsPK2::GUS expression compared with DR5::GUS and PID::GUS in Arabidopsis. PsPK2::GUS, DR5::GUS, and PID::GUS expression in Arabidopsis shoots is mainly localized in the stipules, hydathodes, veins, developing leaves, and cotyledons. Unlike DR5::GUS, PsPK2::GUS, and PID::GUS are weakly expressed in root tips. Both DR5::GUS and PsPK2::GUS are induced by different auxins and are more sensitive to methyl indole acetic acid, 4-chloro-indole acetic acid, and α-naphthalene acetic acid than others. GA(3) has no significant effect on GUS activity in DR5::GUS-transformed seedlings compared to the control, but induction by auxin and gibberellin in combination is synergistic. Cytokinin increases auxin transport in Arabidopsis seedlings. Auxin, gibberellin, and cytokinin all increase GUS activity in shoots of PsPK2::GUS transformed plants compared to the control. However, only auxin and gibberellin increase GUS activity in PID::GUS shoots. In conclusion, auxin, gibberellin, and cytokinin positively regulate PsPK2 expression in shoots, but not in roots. Auxin and gibberellin also upregulate AtPIN1 and LEAFY expression, which is similar to PsPIN1 and Uni in pea. With minor exceptions, the orthologous genes from both species are regulated similarly.