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Earlier studies have shown that of the four genes (Hsp60A, Hsp60B, Hsp60C, Hsp60D genes) predicted to encode the conserved Hsp60 family chaperones in Drosophila melanogaster, the Hsp60A gene (at the 10A polytene region) is expressed in all cell types of the organism and is essential from early embryonic stages, while the Hsp60B gene (at 21D region) is expressed only in testis, being essential for sperm individualization. In the present study, we characterized the Hsp60C gene (at 25F region), which shows high sequence homology with the other three Hsp60 genes of D. melanogaster. In situ hybridization of Hsp60C-specific riboprobe shows that expression of this gene begins in late embryonic stages (stage 14 onwards), particularly in the developing tracheal system and salivary glands; during larval and adult stages, it is widely expressed in many cell types but much more strongly in tracheae and in developing and differentiating germ cells. A P-insertion mutant (Hsp60C(1)) allele with the P transposon inserted at -251 position of the Hsp60C gene promoter was generated. This early larval recessive lethal mutation significantly reduces levels of Hsp60C transcripts in developing tracheae and this is associated with a variety of defects in the tracheal system, including lack of liquid clearance. About 10% of the homozygotes survive as weak, shortlived and completely sterile adults. Testes of the surviving mutant males are significantly smaller, with fewer spermatocytes, most of which do not develop beyond the round spermatid stage. In situ and Northern hybridizations show significantly reduced levels of the Hsp60C transcripts in Hsp60C(1) homozygous adult males. The absence of early meiotic stages in the Hsp60C(1) homozygous testes contrasts with the effect of testis-specific Hsp60B (21D) gene, whose mutation affects individualization of sperm bundles later in spermiogenesis. In view of the specific effects in tracheal development and in early stages of spermatogenesis, it is likely that, besides its functions as a chaperone, Hsp60C may have signalling functions and may also be involved in cation transport across the developing tracheal epithelial cells.

Bipolar resistive switching using organic molecule is very promising for memory applications owing to their advantages, such as simple device structure, low manufacturing cost, stability, and flexibility. Herein we report Langmuir–Blodgett (LB) and spin-coated-film-based bipolar resistive switching devices using organic material 1,4-bis­(di­(1H-indol-3-yl)­methyl)­benzene (Indole1). The pressure–area per molecule isotherm (π–A), Brewster angle microscopy (BAM), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were used to formulate an idea about the organization and morphology of the organic material onto thin films. On the basis of the device structure and measurement protocol, it is observed that the device made up of Indole1 shows nonvolatile resistive random access memory (RRAM) behavior with a very high memory window (∼106), data sustainability (5400 s), device yield (86.7%), and repeatability. The oxidation–reduction process and electric-field-driven conduction are the keys behind such switching behavior. Because of very good data retention, repeatability, stability, and a high device yield, the switching device designed using compound Indole1 may be a potential candidate for memory applications.

Interest in biodegradable and transient electronics is gaining due to their potential use in green electronics, biomedical devices, and sustainable solutions for ewastes. In this paper we employed Protamine Sulfate (PS) as the active layer to demonstrate biodegradable transient resistive memory devices. The Au/PS/ITO device exhibits nonvolatile resistive switching with write-once-read-many (WORM) memory behavior. The observed WORM memory performance was very good with high memory window (4.57× 10 3 ), data retention (experimentally >10 6 s, extrapolated >10 8 s), device yield (∼87.5%), read endurance (>3.6 × 10 4 ), and device stability (>210 days). Bias induced charge trapping followed by conducting filament formation was the key to such switching. The electronic as well as optical behavior completely disappeared after 8 min of dissolution of the device in aqueous solution. As a whole this work suggests that the PS based WORM memory device may be a potential candidate toward designing biodegradable transient memory devices.

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