Threshold of octave masking as a tool to explain cochlear nonlinearity

Background and Aim: The threshold of octave masking test has been used to assess the growth rate of aural harmonics, the intercept point helped differentiate between normal-hearing individuals and sensorineural hearing loss due to noise exposure. With fewer literatures that have been documented, there is a need to explore this test procedure, and hence the purpose of this research is to evaluate the utility of the threshold of octave masking (TOM) procedure in understanding the frequency selectivity and non-linear function of cochlea. Methods: A total of 10 adults (20 ears) were con­sidered for the test. The TOM test procedure was performed on the subjects where the subjects had to identify the presence of a maskee tone (1 kHz) in the presence of a masker tone (500 Hz) across 5 dB increment of masker tone until the subjects uncomfortable level. A line graph was drawn, extrapolated to identify the point of intercept, which is the threshold of octave masking. Results: Results reveal that 17 ears did not have a linear growth but had a 10 to 20 dB gap after a particular maskee level. The intercept point of the initial two extreme points was relatively more than the intercept point of the extreme points at higher intensities. Conclusion: Results from the present study have thrown light on the fact that TOM can be used as a test to measure the frequency selectivity along with the tests of psychophysical tuning curves, notched noise method, non-simultaneous masking, and other non-peripheral masking phenomena

Influence of severe drought on mineral nutrient status in eastern white pine (Pinus strobus L)

AbstractThe photochemical process of photosynthesis is significantly influenced by the availability of nutrients. The purpose of this research is to ascertain how photosynthetic pigment function is affected by nutrient elemental changes caused by severe drought stress. Using elemental analysis, we looked at the changes in mineral nutrient composition in eastern white pine (Pinus strobus L) seedlings 32 days after drought treatment. According to our findings, severe drought resulted in a significant and non-significant decrease in the contents of Chl “b and a”, respectively. The elemental composition of iron (Fe), zinc (Zn), magnesium (Mg), potassium (K), phosphorus (P) and nitrogen (N) was measured. After severe drought treatment, leaf nutrient status showed a significant decline in total N (control-1.57 ± 0.1; drought-0.65 ± 0.07), P (control-959.4 ± 17; drought-645 ± 46), Mg (control-1030.4 ± 33; drought-750.7 ± 76), and K (control-3062.5 ± 32; drought-1853.3 ± 198), with a non-significant decrease in leaf Fe (control-120.3 ± 20; drought-98.9 ± 28) and increase in leaf Zn (control-33.49 ± 2; drought-39.05 ± 4). A positive correlation was found between the content of Fe, P, Mg, K, and N in leaf Chl “b”, but only a positive correlation was found between the content of Zn in leaf Chl “a” during severe drought. During severe drought, nutrient reallocation has a significant impact on leaf chlorophyll levels, as evidenced by this correlation

Short-term severe drought influences root volatile biosynthesis in eastern white pine (Pinus strobus L)

Climate change-related drought stress is expected to shift carbon partitioning toward volatile organic compound (VOC) biosynthesis. The effect of drought stress on VOC synthesis remains unknown in several tree species. Therefore, we exposed eastern white pine (Pinus strobus) plants to severe drought for 32 days and performed physiological analysis (chlorophyll content, leaf water content, and root/shoot index), biochemical analysis (non-structural carbohydrates, proline, lipid peroxidation, and antioxidant assay), and total root VOC analysis. Drought stress decreased the relative water and soil moisture contents. Root proline accumulation and antioxidant activity increased significantly, whereas leaf chlorophyll synthesis and fresh weight decreased significantly in drought-treated plants. A non-significant increase in sugar accumulation (leaves and roots), proline accumulation (leaves), antioxidant activity (leaves), and lipid peroxidation (leaves and roots) was observed in drought-treated plants. Drought stress caused a non-significant decline in root/shoot ratio and starch accumulation (leaves and roots) and caused a significant increase in root abscisic acid content. Drought-treated plants showed an increase in overall monoterpene synthesis (16%) and decline in total sesquiterpene synthesis (3%). Our findings provide an overall assessment of the different responses of VOC synthesis to severe water deficit that may help unravel the molecular mechanisms underlying drought tolerance in P. strobus.Y

Identification and Bioinformatic Analysis of the GmDOG1-Like Family in Soybean and Investigation of Their Expression in Response to Gibberellic Acid and Abscisic Acid

Seed germination is one of the most important stages during plant life cycle, and DOG1 (Delay of germination1) plays a pivotal regulatory role in seed dormancy and germination. In this study, we have identified the DOG1-Like (DOG1L) family in soybean (Glycine max), a staple oil crop worldwide, and investigated their chromosomal distribution, structure and expression patterns. The results showed that the GmDOG1L family is composed of 40 members, which can be divided into six subgroups, according to their evolutionary relationship with other known DOG1-Like genes. These GmDOG1Ls are distributed on 18 of 20 chromosomes in the soybean genome and the number of exons for all the 40 GmDOG1Ls varied greatly. Members of the different subgroups possess a similar motif structure composition. qRT-PCR assay showed that the expression patterns of different GmDOG1Ls were significantly altered in various tissues, and some GmDOG1Ls expressed primarily in soybean seeds. Gibberellic acid (GA) remarkably inhibited the expression of most of GmDOG1Ls, whereas Abscisic acid (ABA) inhibited some of the GmDOG1Ls expression while promoting others. It is speculated that some GmDOG1Ls regulate seed dormancy and germination by directly or indirectly relating to ABA and GA pathways, with complex interaction networks. This study provides an important theoretical basis for further investigation about the regulatory roles of GmDOG1L family on soybean seed germination