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The species-habitat association analysis facilitates a better understanding of species coexis-tence and community assembly. Here, all trees in a 25-hm 2 broadleaved deciduous forest plot in the Qinling Mountains of North-central China were classified into three life stages ( i.e ., seedling, sapling, and adult). The Torus-translation test was used to examine the species-habitat association. The results showed that the association of species with habitats varied across different species. Most species were significantly associated with high slopes, 95.7% of which showed negative association. 89.5% and 90.9% of tree species were negatively associated with low slopes and ridges, respectively. Most species had positive association with high valley, with only one negative association (0.03%). There were 80, 44 and 23 significant associations with habitats at seedling, sapling and adult stages, respectively, indicating that a greater dependence of seedlings on habitat. 38 species at seedling stage and 25 species at the sapling stage were associated with at least one habitat type, while only 17 species at the adult stage were significantly associated. The effects of habitat on species varied across life stages, showing a weaker species-habitat association at the later stage. Due to the specific environmental demands, most species showed different habitat preferences across life stages.

Objective: To trace the source of human H7N9 cases in Huai'an and elucidate the genetic characterization of Huai'an strains associated with both humans and birds in live poultry market., Methods: An enhanced surveillance was implemented when the first human H7N9 case was confirmed in Huai'an. Clinical specimens, cloacal swabs, and fecal samples were collected and screened by real-time reverse transcription-polymerase chain reaction (RT-PCR) for H7N9 virus. The positive samples were subjected to further RT-PCR and genome sequencing. The phylodynamic patterns of H7N9 virus within and separated from Huai'an and evolutionary dynamics of the virus were analyzed., Results: Six patients with H7N9 infection were previously exposed to live poultry market and presented symptoms such as fever (>38.0 °C) and headaches. Results of this study support the hypothesis that live poultry markets were the source of human H7N9 exposure. Phylogenetic analysis revealed that all novel H7N9 viruses, including Huai'an strains, could be classified into two distinct clades, A and B. Additionally, the diversified H7N9 virus circulated in live poultry markets in Huai'an. Interestingly, the common ancestors of the Huai'an H7N9 virus existed in January 2012. The mean nucleotide substitution rates for each gene segment of the H7N9 virus were (3.09-7.26)×10-3 substitutions/site per year (95% HPD: 1.72×10-3 to 1.16×10-2)., Conclusion: Overall, the source of exposure of human H7N9 cases in Huai'an was live poultry market, and our study highlights the presence of divergent genetic lineage of H7N9 virus in both humans and poultry specimens in Huai'an., (Copyright © 2016 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.)

Medicine mulberry (Morus nigra) mainly distributed in southern areas of Xinjiang Uighur Autonomous Region and introduced by grafting, is a unique Morus species, whose plant number is little. As a traditional herbal medicine, medicine mulberry with high levels of secondary metabolites has important values of scientific research and utilization. In order to solve the introduction problems for medicine mulberry, we have established its rapid propagation system through tissue culture since 2011. The shoots of medicine mulberry through tissue culture were transplanted into the field to carry out an introduction experiment. Here, we firstly reported that the growth status and pest and disease occurrence of medicine mulberry in the field of Chongqing and found that the medicine mulberry through tissue culture had well-developed root system, it showed better growth than medicine mulberry by grafting technique, and Pseudodendrothrips moil was a major pest of medicine mulberry. The introduction technique for medicine mulberry established successfully in this study could lay the foundation for large-scale cultivation and high efficiency utilization of medicine mulberry., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Chinese Pharmaceutical Association.)

Spinosyns A and D are novel macrolide secondary metabolites containing two deoxysugars. Each of the sugars is derived from a common intermediate, which is biosynthesized sequentially by NDP-glucose synthase and glucose dehydratase. Systematical duplication of gtt and gdh was carried out by genetic engineering in Saccharopolyspora spinosa. Introduction of additional gtt and gdh genes under the control of PermE* promoter showed significant increase on their transcript levels. The production of spinosad was increased by over threefold to reach 800 μg/ml in the recombinant strain SIPI-M2093.

Detection of amplitude modulation (AM) in 500 and 4000 Hz tonal carriers was measured as a function of modulation frequency from younger and older adults with normal hearing through 4000 Hz. The modulation frequency above which sensitivity to AM increased ("transition frequency") was similar for both groups. Temporal modulation transfer function shapes showed significant age-related differences. For younger subjects, AM detection thresholds were generally constant for low modulation frequencies. For a higher carrier frequency, AM detection thresholds then increased as modulation frequency further increased until the transition frequency. In contrast, AM detection for older subjects continuously increased with increasing modulation frequency, indicating an age-related decline in temporal resolution for faster envelope fluctuations. Significant age-related differences were observed whenever AM detection was dependent on temporal cues. For modulation frequencies above the transition frequency, age-related differences were larger for the lower frequency carrier (where both temporal and spectral cues were available) than for the higher frequency carrier (where AM detection was primarily dependent on spectral cues). These results are consistent with a general age-related decline in the synchronization of neural responses to both the carrier waveform and envelope fluctuation.

As part of an ongoing study of age-related changes in auditory processing, sensitivity to small changes in frequency were assessed using the cortical auditory evoked potential, P1-N1-P2, in younger and older adults with normal hearing. Behavioral measures have shown age-related differences in intensity and frequency discrimination that are larger at lower than higher frequencies. However, substantial individual differences and equivocal results among studies have been reported. This variability may reflect differences in tasks and procedures, as well as subject variables, such as hearing sensitivity and level of attention. To minimize these subject variables, the P1-N1-P2 response was investigated using a passive listening paradigm. Subjects were 10 younger and 10 older adults. The P1-N1-P2 was elicited by a 150-ms change in frequency in otherwise continuous 500-Hz and 3000-Hz pure tones presented at 70 dB SPL. P1-N1-P2 threshold was defined as the smallest change in frequency needed to evoke a P1-N1-P2 response. Furthermore, a frequency-dependent aging effect was observed for P1-N1-P2 thresholds, such that older subjects were significantly less sensitive to the frequency change than younger subjects, with significantly larger age-related differences at 500 Hz than at 3000 Hz. Age-related changes in response latencies and amplitude of the P1-N1-P2 response were also evident at 500 and 3000 Hz. These results are consistent with age-related changes in the central auditory system and suggest that changes in frequency discrimination abilities of older adults may be, in part, related to changes in preattentive levels of auditory processing.

Recently, the study of achaete-scute (AS-C) homologues has contributed enormously to understanding of gene duplication and function evolution, particularly in Diptera. We identified four AS-C homologue genes in the silkworm, Bombyx mori, referred to as BmASH, BmASH2, BmASH3, and Bmase. The complex displayed tandem array structure in the genome. Analysis of spatial expression profiles showed that they all were expressed in obviously higher levels in wing disc than in other tissues, suggesting that they might play important roles in the development of the wing. Furthermore, we found that their expression profiles in the wing discs were mostly correlated with the development of the scales, especially the BmASH gene. RNA interference results further indicated that BmASH was necessary for scale formation in silkworm wing.

As part of an ongoing study of auditory aging, detection of sinusoidal and quasitrapezoidal frequency modulation (FM) was measured with a 5-Hz modulation frequency and 500- and 4000-Hz carriers in two experiments. In Experiment 1, psychometric functions for FM detection were measured with several modulation waveform time patterns in younger adults with normal hearing. Detection of a three-cycle modulated signal improved when its duration was extended by a preceding unmodulated cycle, an effect similar to adding a modulated cycle. In Experiment 2, FM detection was measured for younger and older adults with normal hearing using two psychophysical methods. Similar to frequency discrimination, FM detection was poorer in older than younger subjects and age-related differences were larger at 500 Hz than at 4000 Hz, suggesting that FM detection with low modulation frequencies and frequency discrimination may share common underlying mechanisms. One mechanism is likely related to temporal information coded by neural phase locking which is strong at low frequencies and decreases with increasing frequency, as observed in animals. The frequency-dependent aging effect suggests that this temporal mechanism may be affected by age. The effect of psychophysical method was sizable and frequency dependent, whereas the effect of modulation waveform was minimal.

HWTX-I is a peptide neurotoxin purified from the crude venom of the Chinese bird Spider Selenocosmia Huwena, which has analyesic activity. rHWTX-I expressed by P. pastoris and secreted to culture supernatant was first precipitated by (NH4)2SO4, then it was isolated and desalted by ultrofiltration following by ion exchange chromatography of CM column, after reverse phase HPLC of C18 column and vacuum drying, the pure HWTX-I protein was obtained which was proved to be recombinant HWTX-I by Tricine SDS-PAGE, MALDI-TOF mass spectrometry, amino acid composition analysis, the N-terminal amino acid sequence and its biological activity. The final yield of the purified HWTX-I was about 80 mg/L accounting for 23.6% of its total secretory proteins.

A chitosanase was purified from the culture fluid of the chitino- and chitosanolytic bacterium Burkholderia gladioli strain CHB101. The purified enzyme (chitosanase A) had a molecular mass of 28 kDa, and catalyzed the endo-type cleavage of chitosans having a low degree of acetylation (0-30%). The enzyme hydrolyzed glucosamine oligomers larger than a pentamer, but did not exhibit any activity toward N-acetylglucosamine oligomers and colloidal chitin. The gene coding for chitosanase A (csnA) was isolated and its nucleotide sequence determined. B. gladioli csnA has an ORF encoding a polypeptide of 355 amino acid residues. Analysis of the N-terminal amino acid sequence of the purified chitosanase A and comparison with that deduced from the csnA ORF suggests post-translational processing of a putative signal peptide and a possible substrate-binding domain. The deduced amino acid sequence corresponding to the mature protein showed 80% similarity to the sequences reported from Bacillus circulans strain MH-K1 and Bacillus ehimensis strain EAG1, which belong to family 46 glycosyl hydrolases.

Psychometric functions for gap detection of temporal gaps in wideband noise were measured in a "yes/no" paradigm from normal-hearing young and aged subjects with closely matched audiograms. The effects of noise-burst duration, gap location, and uncertainty of gap location were tested. A typical psychometric function obtained in this study featured a steep slope, which was independent of most experimental conditions as well as age. However, gap thresholds were generally improved with increasing duration of the noise burst for both young and aged subjects. Gap location and uncertainty had no significant effects on the thresholds for the young subjects. For the aged subjects, whenever the gap was sufficiently away from the onset or offset of the noise burst, detectability was robust despite uncertainty about the gap location. Significant differences between young and aged subjects could be observed only when the gap was very close to the signal onset and offset.

Although a psychometric function describing a subject's responses to some physical stimuli is of considerable value, characterizing such functions is time consuming and, hence, is not carried out routinely in psychophysical experiments. A principal reason for the lack of efficiency in characterizing a psychometric function is the use of sampling methods that either converge on a single point on the psychometric function, such as the PEST method, or which distribute observations uniformly over a wide range, such as the constant stimuli method. As an alternative, a multimodal four-point sampling method has been proposed [C. F. Lam, J. H. Mills, and J. R. Dubno, J. Acoust. Soc. Am. 99, 3689-3693 (1996)]. A psychometric function is then fitted to the four points (each with several trials) to estimate the threshold and slope parameters of the psychometric function. Adaptive methods, such as the up-down methods [H. Levitt, J. Acoust. Soc. Am. 49, 467-477 (1971)], can be used to provide good initial estimates of the threshold and spread parameters of a psychometric function described by a logistic function. In ongoing studies of age-related changes in auditory masking and discrimination, this new four-point sampling method has been applied to determine psychometric functions for absolute thresholds as a function of duration, thresholds in simultaneous and forward masking, frequency discrimination, and intensity discrimination in both young and aged human subjects. Results indicate that a reduction in data collection time of about 50% with no increase in variance can be achieved. This increase in efficiency applies to simple detection tasks by normal hearing subjects as well as to complex discrimination tasks by older subjects with hearing loss.

The fine structures of 2f1-f2 acoustic distortion products (ADP) were measured in four groups of human subjects: (1) young with normal hearing, (2) aged with normal or near-normal hearing, (3) aged subjects with more severe hearing loss above 2000 Hz, and (4) young with hearing similar to those of the normal- or near-normal-hearing aged group. The purpose of this study was to investigate how ADP fine structure changes with age and hearing loss. Results show that the fine structure is observable whenever the ADP is measurable, and its sharpness, defined as the peak-to-peak frequency distance, is independent of age hearing loss, and longitudinal amplitude change. There is a large variance in ADP peak amplitudes in aged subjects with or without hearing loss as compared to young normal hearing subjects, the aged group generally having lower peak amplitudes than those of the young group. According to an ANOVA analysis with absolute threshold as covariate, the null hypothesis stating that there is no aging effect on the ADP peak responses cannot be ruled out, a conclusion similar to that made by Stover and Norton [J. Acoust. Soc. Am. 94, 2670-2681 (1993)]. On the other hand, threshold changes cannot explain all the differences in ADP amplitude. It is clear that the relationship between ADP amplitudes and behavioral thresholds can differ between young and aged populations. At primary levels of 50 dB SPL, almost normal ADP magnitudes are often found in aged subjects even when associated with a 35-dB hearing loss, whereas for young subjects ADPs typically were not measurable when associated with the pure-tone thresholds of 20 dB HL or higher. This dichotomy may be explained by the different etiologies of cochlear pathologies predominant in the two groups.

In a previous article, a vector sum model was developed that successfully reproduces the ADP rippling pattern when a nonuniformity is introduced in the active damping factor, a parameter that is inversely related to the energy gain contribution of the outer hair cells [OHCs, Sun et al., J. Acoust. Soc. Am. 96, 2166-2174 (1994)]. Here, the mean of the damping factor is increased nonlinearly with input level, mimicking the saturation of the active feedback of the OHCs. The passive damping factor in the transmission line model was also nonlinearly increased with input level to reproduce the frequency shift of the peak of the traveling wave observed in experimental data. The resulting model simulates an ADP that is compatible with data from human subjects wherein the ADP fine structure does not saturate with level. Moreover, the model suggests that the shifting of the ADP pattern with level is a direct result of the peak shift of the traveling wave, thus implicating the nonlinear damping factors as the underlying basis of this phenomenon. The input/output (I/O) functions of the simulated ADP emissions at specific frequencies were also examined. The resulting functions show a variety of shapes, depending on the pattern of ADP fine structure around the I/O frequency, and the way the fine structure shifts as primary levels increase. These I/O functions are also similar to those observed in human subjects, even with regard to overall slopes which approximate one. Thus the model illustrates how cubic distortion generators coupled with damping on linearities can yield I/O function slopes on the order of one, rather than the expected three.(ABSTRACT TRUNCATED AT 250 WORDS)

The fine structure of the 2f1-f2 acoustic distortion product (ADP) as a function of frequency has been measured in human subjects and shows a series of sharp peaks and valleys (rippling) with peak-to-valley level differences of up to 15-20 dB. In order to delineate the cause of the ADP rippling pattern, a computer model was developed to simulate the behavior of the ADP, specifically the ADP fine structure. The ADP model includes the middle ear and cochlea. The middle ear was treated as a simple signal delivery system in both the forward and reverse directions. The ADP was assumed to be generated within the cochlea by nonlinear elements taken to be the outer hair cells (OHCs), and an array of ADP generators was used to simulate the OHCs along the basilar membrane (BM). The magnitude and phase of the output of each of the ADP generators were functions of the local responses of the two primary traveling waves. The traveling waves were calculated from a passive transmission line model of the BM using the WKB approximation, coupled to a second-order resonance to mimic the contribution from active OHC feedback. The system output of ADP in dB was proportional to the weighted vectorial sum of all the components, arriving at the stapes. Parameters such as lateral coupling and feedback gain were examined.

The fine frequency structure of the 2f1-f2 acoustic distortion product (ADP fine structure) was examined in ten human subjects with normal hearing. Primary frequencies (f1 and f2) were incremented in steps of 1/32 octave with an f2/f1 ratio of 1.2. The primary levels were kept equal to each other and varied from 45 to 65 dB SPL in 2.5-dB steps. The results show that the ADP fine structure is characterized by a series of peaks and valleys across frequency, with a peak-to-peak frequency spacing of about 3/32 octave and a peak-to-valley amplitude ratio of up to 20 dB. At frequencies below 4000 Hz, as primary level increases, the sharpness of the ADP fine structure is not significantly reduced and the pattern gradually shifts to lower frequencies. At frequencies above 4000 Hz, a flattening of the pattern is sometimes observed at high levels. A consequence of the underlying process responsible for the fine structure is that ADP input/output (I/O) functions can be highly variable in shape. Dramatic shape changes can occur for ADP I/O functions obtained with primary frequency changes of as little as 1/32nd of an octave. The outward cause of I/O function variability is the behavior of the ADP fine structure with level; i.e., it remains robust at high levels and systematically shifts to lower frequencies with level. As a result, ADP peaks can shift to valleys with increasing level and vice versa. Thus, small shifts in primary frequency can result in significant changes in the shape of the ADP I/O function in humans.