Transgenerational Inheritance: Parental Guidance Suggested

The Conjusome-A Transient Organelle Linking Genome Rearrangements in the Parental and Developing Macronuclei

The conjusome plays an important role in the conjugation events that occur in Tetrahymena thermophila. The conjusome appears in the anterior of conjugant pairs during the early stages of new macronuclei (anlagen) development. It lacks a membrane, and is composed of a network of fibrous, electron dense material, containing background cytoplasm and ribosomes. Several proteins localize to this organelle, including Pdd1p, a chromodomain protein that participates in the formation of chromatin-containing structures in developing macronuclear anlagen, and is associated with the elimination of specific germ-line sequences from developing macronuclei. Conjugants lacking the PDD1 allele in the parental macronucleus do not show Pdd1p antibody staining in conjusomes. Investigations were performed using mutant cell lines, uniparental cytogamy and drug treatment, and show that the conjusome appears to be dependent on parental macronuclei condensation, and is a transitory organelle that traffics nuclear determinants from the parental macronucleus to the developing anlagen. These data, taken together with Pdd1p knockout experiments, suggest the conjusome is involved in the epigenetic phenomena that occur during conjugation and sexual reorganization. This is likely a conserved organelle. Conjusome-like structures were also observed in another Ciliate, Stylonichia. In general, conjusomes have features that resemble germ line P-granules.

Exposure to sublethal doses of insecticide and their effects on insects at cellular and physiological levels

Insecticides were used as pest management tools for a long time. The appearance of resistant insects has led the scientific community to rethink their use and to study the mechanisms underlying the resistance in order to circumvent it. However, we know now that sublethal doses of insecticide induce many effects which should be taken into account for pest control. In this review, we summarized current knowledge on mechanisms used by insects to deal with exposure to sublethal dose of insecticides. Physiological and cellular changes could contribute to the adaptation of the insect to its environment making the challenge of managing pests difficult.