WFS1 and non-syndromic low-frequency sensorineural hearing loss: A novel mutation in a Portuguese case

Low-frequency sensorineural hearing loss (LFSNHL) is an unusual type of HL in which frequencies at 2000 Hz and below are predominantly affected. Most of the families with LFSNHL carry missense mutations in WFS1 gene, coding for wolframin.     

Using a Lethality Index to Assess Susceptibility of Tribolium confusum and Oryzaephilus surinamensis to Insecticides

We evaluated knockdown caused by four insecticides: alpha-cypermethrin, chlorfenapyr, pirimiphos-methyl and fipronil against adults of Tribolium confusum Jacquelin Duval, the confused flour beetle and Oryzaephilus surinamensis (L.), the sawtoothed grain beetle. Bioassays were conducted on concrete and metal surfaces. Adults of the tested species were exposed on both surfaces treated with the above insecticides at two doses (low and high). Knockdown assessment was done after 15, 30 and 60 min of adult exposure in the treated surfaces. Also, after 1, 3, 5, 7 and 14 d of exposure, a lethality index was calculated with an equation resulting to values from 0 to 100, where 100 indicated complete mortality and 0 complete survival. We also developed a lethality index by ranking each adult on each surface from 0 to 4, 0: adults moved normally, 1: adults were knocked down, but were able to walk for short intervals, 2: adults were knocked down and unable to walk, but with visible movement of antennae etc., 3: adults were knocked down, with very minimal movement of the tarsi and the antennae and 4: adults were dead (no movement). Knockdown of adults immediately after exposure (15–60 min) was higher for pirimiphos-methyl followed by alpha-cypermethrin, for both dose rates tested and species, but only on the metal surface. The lethality index was nearly 100 for all insecticides after 5d of exposure for O. surinamensis, while for T. confusum the adult lethality index was considerably lower for alpha-cypermethrin, suggesting that that recovery from knockdown occurred. Chlorfenapyr was the only insecticide that was more effective on concrete than on metal, while the reverse was noted for the other three insecticides. These results show that knockdown has different levels, which can be used as indicators of insect mortality or recovery.     

Development of efficient suicide mechanisms for biological containment of bacteria

To optimize plasmid containment, we have systematically investigated the factors that limit the killing efficiency of a suicide system based on the relF gene from Escherichia coli controlled by inducible lac promoters and placed on plasmids. In induction experiments with this suicide system, killing efficiency was unaffected by temperature and growth medium; there was no requirement for great promoter strength or high plasmid copy number. We could demonstrate that the factors limiting killing were the mutation rate of the suicide function and the reduced growth rate caused by a basal level of expression of the suicide gene during normal growth, which can give a selective growth advantage to cells with mutated suicide functions. The capacity of the plasmid-carried killing system to contain the plasmid was tested in transformation, transduction, and conjugational mobilization. The rate of plasmid transfer detected in these experiments seemed too high to provide adequate biological containment. As expected from the induction experiments, plasmids that escaped containment in these transfer experiments turned out to be mutated in the suicide function. With lac-induced suicide as a test, the efficiency of the system was improved by tightening the repression of the suicide gene, thereby preventing selection of cells mutated in the killing function. Reduction of the mutational inactivation rate of the suicide system by duplication of the suicide function augmented the efficiency of the suicide dramatically. These results permit the construction of extremely efficient biological containment systems.     

Effects of starvation and sucrose feeding on corpora allata of last instar larvae of Manduca sexta: in vitro activity, size, and cell number

Abstract Larvae of the tobacco hornworm moth Manduca sexta starved for the first 3 days of the last (fifth) stadium undergo a supernumerary moult. If they are provided with sucrose during the starvation period, they develop into normal pupae although pupation is delayed. The activities of the corpora allata (CA) from normal, starved, and sucrose fed larvae were followed through the fifth stadium with a radiochemical assay for Juvenile Hormone (JH) biosynthesis. An attempt was made to correlate CA-activity with CA cell number, size, and protein content.
In CA of normally fed larvae the rate of JH synthesis declined to undetectable levels by day 4 which was also the time of exposure of the dorsal vessel. In CA of starved larvae, the rate of JH synthesis at first decreased but began to increase on day 3 and reached a peak value by day 7 , at which time head capsule slippage occurred. In CA of sucrose fed larvae, the rate of biosynthesis declined as in normal larvae but the decline was extended over a longer period. Exposure of the dorsal vessel was delayed in the same manner and occurred on days 7–9. The major JH in all cases was JH-II.
The CA comprise c. 150 cells in the early fifth stadium, and this number remained constant during the fifth stadium in all three feeding regimens. In normal larvae, CA size and protein content increased several-fold during the stadium whereas in starved and sucrose-fed larvae they increased slowly and in agreement with the altered timing of developmental events. In none of the groups was the CA activity pattern correlated with morphometric changes of the CA. The rates of JH biosynthesis were not closely correlated with published JH titre curves. The in vivo mechanisms for regulation of JH production remain to be elucidated.     

HEDONIC SPREADABILITY OPTIMA OF SELECTED EDIBLE FATS

A panel of untrained judges was asked to assess spreadability of selected solid edible fat samples (butter, margarine, low fat products) of different temperature with regard to hedonic preferences. Instrumental measurements were performed by cone penetration with constant load. The statistical analysis of the ranked sensory data showed significant spreadability optima in the apparent yield value range of approximately 30–60 kPa. Differences between the selected fats were not observed.     

The main immunogenic region (MIR) of the nicotinic acetylcholine receptor and the anti-MIR antibodies

Myasthenia gravis (MG) is caused by autoantibodies against the nicotinic acetylcholine receptor (AChR) of the neuromuscular junction. The anti-AChR antibodies are heterogeneous. However, a small region on the extracellular part of the AChR alpha subunit, called the main immunogenic region (MIR), seems to be the major target of the anti-AChR antibodies, but not of the specific T-cells, in experimental animals and possibly in MG patients. The major loop of the overlapping epitopes for all testable anti-MIR monoclonal antibodies (MAbs) was localized within residues 67-76 (WNPADYGGIK for Torpedo and WNPDDYGGVK for human AChR) of the alpha subunit. The N-terminal half of alpha 67-76 is the most critical, Asn68 and Asp71 being indispensable for binding. Yet anti-MIR antibodies are functionally and structurally quite heterogeneous. Anti-MIR MAbs do not affect channel gating, but they are very potent in mediating acceleration of AChR degradation (antigenic modulation) in cell cultures and in transferring experimental MG in animals. Fab fragments of anti-MIR MAbs bound to the AChR prevent the majority of the MG patients' antibodies from binding to and causing loss of the AChR. Whether this inhibition means that most MG antibodies bind on the same small region or is a result of broad steric/allosteric effects is under current investigation.     

A preliminary report on a bacteriological assay for compound 1080 (sodium monofluoroacetate)

A new, inexpensive, simple and rapid bioassay for sodium monofluoroacetate (compound 1080) was developed using bacteria. Two 1080-sensitive isolates ( Bacillus sp. DHW and Acinetobacter sp. DHW) from local aquatic environments were tested on different agar media using the disc diffusion technique. Both bacteria exhibited zones of growth inhibition surrounding the 1080 discs that were linearly proportional to the concentrations (log₁₀) of 1080. Preliminary studies indicate that this technique can be used for assaying 1080 in environmental and biological samples.