Increased Expression of β-Amyloid Protein Precursor and Microtubule-Associated Protein τ During the Differentiation of Murine Embryonal Carcinoma Cells

Expression of the genes encoding the beta/A4 amyloid protein precursor (APP) and microtubule-associated protein tau was studied in an embryonal carcinoma cell line (P19) that differentiates in vitro into cholinergic neurons after treatment with retinoic acid. Expression of APP increased 34- (mRNA) and 50-fold (protein) during neuronal differentiation; APP-695 accounted for most of this increase. These remarkable increases in APP expression coincided with a proliferation of neuronal processes and with an increase in content of tau mRNA. Moreover, subsequent decreases in the levels of APP and tau mRNA coincided with the onset of the degeneration of the neuronal processes. Immunocytochemical staining suggested that greater than 85% of the P19-derived neurons are cholinergic and that APP is present in the neuronal processes and cell bodies. These results suggest that APP may play an important role in construction of neuronal networks and neuronal differentiation and also indicate that this embryonal carcinoma cell line provides an ideal model system to investigate biological functions of APP and the roles of APP and tau protein in development of Alzheimer's disease in cholinergic neurons.     

Peripheral distribution of dermatan sulfate proteoglycans (decorin) in amyloid-containing plaques and their presence in neurofibrillary tangles of Alzheimer's disease.

We used a polyclonal antibody and a mixture of three monoclonal antibodies (MAb), all recognizing the protein core of the small dermatan sulfate proteoglycan (DSPG) (known as PG-II or decorin) derived from human skin fibroblasts, to immunolocalize this molecule in the characteristic lesions in Alzheimer's brain. All antibodies demonstrated positive decorin immunostaining in both the amyloid deposits of neuritic plaques (NPs) and the filamentous structures within neurofibrillary tangles (NFTs). Unlike heparan sulfate proteoglycans (HSPGs), which tend to be evenly distributed throughout NPs containing amyloid fibrils, decorin was primarily localized to the periphery of the spherically shaped amyloid plaques and to the edges of amyloid fibril bundles within the plaque periphery. Decorin was also immunolocalized to the paired helical and straight filaments within NFTs and to collagen fibrils surrounding blood vessels. The unusual distribution of decorin confined to the periphery of amyloid plaques in AD brain suggests that this particular PG may play an important role in the development of the amyloid plaque.     

An Escherichia coli plasmid-based, mutational system in which supF mutants are selectable: Insertion elements dominate the spontaneous spectra

A new system is described to determine the mutational spectra of mutagens and carcinogens in Escherichia coli; data on a limited number (142) of spontaneous mutants is presented. The mutational assay employs a method to select (rather than screen) for mutations in a supF target gene carried on a plasmid. The E. coli host cells (ES87) are lacI⁻ (am26), and carry the lacZΔM15 marker for α-complementation in β-galactosidase. When these cells also carry a plasmid, such as pUB3, which contains a wild-type copy of supF and lacZ-α, the lactose operon is repressed (off). Furthermore, supF suppression of lacl^um26 results in a lactose repressor that has an uninducible, lacl^S genotype, which makes the cells unable to grow on lactose minimal plates. In contrast, spontaneous or mutagen-induced supF⁻ mutations in pUB3 prevent suppresion of lacl^am26 and result in constitutive expression of the lactose operon, which permits growth on lactose minimal plates. The spontaneous mutation frequency in the supF gene is 0.7 and 1.0 × 10⁻⁶ without and with SOS induction, respectively. Spontaneous mutations are dominated by large insertions (67% in SOS-uninduced and 56% in SOS-induced cells), and their frequency of appearance is largely unaffected by SOS induction. These are identified by DNA sequencing to be Insertion Element: IS1 dominates, but IS4, IS5, gamma-delta and IS10 are also obtained. Large deletions also contribute significantly (19% and 15% for - SOS and +SOS, respectively), where a specific deletion between a 10 base pair direct repeat dominates; the frequency of appearance of these mutations also appears to be unaffected by SOS induction. In contrast, SOS induction increases base pairing mutations (13% and 27% for -SOS and +SOS, respectively), The ES87/pUB3 system has many advantages for determining mutational spectra, including the fact that mutant isolation is fast and simple, and the determination of mutational changes is rapid because of the small size of supF.     

The effect of growth hormone and insulin upon MLC responses and the generation of cytotoxic lymphocytes

The ability of growth hormone (GH) and insulin to influence positively T lymphocytes responding to an alloantigen stimulus in vitro was analyzed through the use of a serum substitute system. The presence of insulin but not GH, enables the generation of a successful mixed lymphocyte culture (MLC) blastogenic response. However, the presence of GH during a 5-day MLC allowed for the generation of cytotoxic T lymphocytes (CTL). It was further demonstrated that GH needed to be present during the first 2 days of the culture system, presumably before the entry of the precursor CTL into cell division. The results are discussed in terms of the induction, by the GH, of ornithine decarboxylase activity and how this might relate to the successful generation of CTL activity.     

More accurate removal of the hump in rhinoplasty.

We present a technique to help remove the precise amount of nasal hump at exactly the previously determined level.     

Oxidation of sulfhydryl groups to disulfides by sulfoxides.

Oxidation rates of SH groups in penicillamine, cysteine, and glutathione to the corresponding SS forms by dimethyl sulfoxide and other sulfoxides as a function of pH of the solvent and structure of reactants were measured by NMR spectroscopy. The observed second-order rate constant showed a biphasic pH dependence. A mechanism which rationalizes this result is proposed. These oxidations are proposed to have synthetic utility with biochemical implications.     

Central patterning and reflex control of antennular flicking in the hermit crab Pagurus alaskensis (Benedict).

1. The effects of altering sensory input on the motoneuronal activity underlying antennular flicking have been tested. 2. Removal of the short segments of the outer flagellum results in a reduction of the number of spikes/burst in the fast flexor motoneurones A31F and A32F. 3. During a flick the delay between the burst in motoneurone A31F and the burst in motoneurone A32F is insensitive to alteration of sensory input. 4. Sensory feedback from the flexion phase of a flick is necessary for the activation of either extensor motoneurone. Evidence is presented to suggest that this feedback is primarily from joint-movement receptors at the MS-DS and DS-OF joints. 5. The results are incorporated into a model in which the patterns of flexor activity result from some specified properties of three components: a trigger system, a follower system, and the spike initiating zone of the flexor motoneurones. The trigger system determines when a flick will occur. The follower system determines the number of flexor spikes during a flick. Properties of the spike initiating zone determine the spike frequency and the timing between bursts in the flexor motoneurones. Extensor activity in the model is reflexively elicited by feedback from phasic, unidirectional receptors sensitive to joint flexion. 6. The functional significance of reflex control of extensor activity is discussed in relation to the form and proposed function of antennular flicking. It is suggested that this form of control is adapted to the function of antennular flicking because flexion at the MS-DS joint is not always necessary for the fulfilment of the fuction of a flick.     

An evaluation of antigen-driven expansion and differentiation of hapten-specific B lymphocytes purified from aged mice

Hapten-specific, trinitrophenyl antigen-binding B cells (TNP-ABC) were purified from inbred strains of mice representative of short-, intermediate-, and long-lived animals. Such populations of B cells were stimulated by either thymus-independent or thymus-dependent antigens in vitro and evaluated for both proliferation and differentiation into antibody-secreting cells. In the thymus-dependent system, the three strains of mice were selected on the basis of all being able to interact appropriately with the same T helper cell line. The results indicate that TNP-ABC purified from aged animals of all three strains responded to both forms of antigenic stimulation similar to TNP-ABC selected from young, littermate control animals. These results are discussed in terms of concepts of intrinsic B cell defects during the aging process.     

Establishment of the biological control agent Hypocosmia pyrochroma for Dolichandra unguis-cati (Bignoniaceae) is limited by microclimate

Cat's claw creeper, Dolichandra unguis-cati (Bignoniaceae), a perennial woody vine native to tropical America, is a target for biological control in Australia and South Africa. The cat's claw creeper leaf-tying moth Hypocosmia pyrochroma (Lepidoptera: Pyralidae) from tropical South America was released as a biological control agent for cat's claw creeper in Australia from 2007 to 2010. A total of 2,277 adults, 837 pupae and 77,250 larvae were released at 40 sites in Queensland and New South Wales. Releases were made mostly in open fields (85%), and at limited sites (15%) in insect-proof cages erected over naturally occurring cat's claw creeper infestations in the field. Sampling was conducted annually in spring and autumn to monitor the establishment and dispersal of H. pyrochroma. Establishment of H. pyrochroma was first noticed in 2012 at three release sites and since then the number of established sites has increased to 80 in 2020. Establishment was evident on both ‘short-pod’ and ‘long-pod’ forms of cat's claw creeper and was more widespread in sites where releases were made within insect-proof field cages (50%) than in sites with open field releases (9%). The moth was active from late spring to late autumn with peak larval activity in late summer. To date, all field establishments have been in areas predicted by a CLIMEX model as climatically suitable but restricted mostly to riparian environment (93% of establishment), where the moth has continued to spread from 1.5 to 23 km from release sites. In contrast, there is the only limited establishment and spread in non-riparian corridors, highlighting the role of microclimate (riparian) as a limiting factor for establishment and spread. Future efforts will focus on redistribution of the agent to river/creek systems where the moth is currently not present.