A DNA barcode library for woody plants in tropical and subtropical China

The application of DNA barcoding has been significantly limited by the scarcity of reliable specimens and inadequate coverage and replication across all species. The deficiency of DNA barcode reference coverage is particularly striking for highly biodiverse subtropical and tropical regions. In this study, we present a comprehensive barcode library for woody plants in tropical and subtropical China. Our dataset includes a standard barcode library comprising the four most widely used barcodes (rbcL, matK, ITS, and ITS2) for 2,520 species from 4,654 samples across 49 orders, 144 families, and 693 genera, along with 79 samples identified at the genus level. This dataset also provides a super-barcode library consisting of 1,239 samples from 1,139 species, 411 genera, 113 families, and 40 orders. This newly developed library will serve as a valuable resource for DNA barcoding research in tropical and subtropical China and bordering countries, enable more accurate species identification, and contribute to the conservation and management of tropical and subtropical forests.

Effects of topography and historical disturbance on canopy height structure of tropical forests in Menglun, Xishuangbanna, China

With the combination of airborne Lidar and panchromatic images in 1981 and 2021, we investigated the canopy height structure of tropical forests in Menglun sub-reserve in the Xishuangbanna National Nature Reserve of Yunnan Province, and analyzed its relationship with environmental factors by using multiple regression tree (MRT) method. The results showed that forests in the Menglun sub-reserve could be clustered into seven types based on canopy height structures, with tropical rainforest, monsoon evergreen broad-leaved forest, secondary forest, and flood plain forest as the main types. The potential solar radiation, altitude, terrain profile curvature, slope and the brightness value of imageries in 1981 and 2021 were main factors that drove the classification. The tropical seasonal rainforest dominated by Pometia pinnata occupied the largest area in valley and low-land. The monsoon evergreen broad-leaved forest dominated by Castanopsis echinocarpa mainly distributed in the ridge and disturbed areas. The secondary forests had homogeneous canopy surface, which was significantly different from the primary forests. The activities of swidden agriculture about three decades ago had legacy impacts on the physiognomy of secondary forests.

Adaptive genetic diversity of dominant species contributes to species co-existence and community assembly

The synthesis of evolutionary biology and community ecology aims to understand how genetic variation within one species can shape community properties and how the ecological properties of a community can drive the evolution of a species. A rarely explored aspect is whether the interaction of genetic variation and community properties depends on the species' ecological role. Here we investigated the interactions among environmental factors, species diversity, and the within-species genetic diversity of species with different ecological roles. Using high-throughput DNA sequencing, we genotyped a canopy-dominant tree species, Parashorea chinensis, and an understory-abundant species, Pittosporopsis kerrii, from fifteen plots in Xishuangbanna tropical seasonal rainforest and estimated their adaptive, neutral and total genetic diversity; we also surveyed species diversity and assayed key soil nutrients. Structural equation modelling revealed that soil nitrogen availability created an opposing effect in species diversity and adaptive genetic diversity of the canopy-dominant Pa. chinensis. The increased adaptive genetic diversity of Pa. chinensis led to greater species diversity by promoting co-existence. Increased species diversity reduced the adaptive genetic diversity of the dominant understory species, Pi. kerrii, which was promoted by the adaptive genetic diversity of the canopy-dominant Pa. chinensis. However, such relationships were absent when neutral genetic diversity or total genetic diversity were used in the model. Our results demonstrated the important ecological interaction between adaptive genetic diversity and species diversity, but the pattern of the interaction depends on the identity of the species. Our results highlight the significant ecological role of dominant species in competitive interactions and regulation of community structure.

Plastome-based phylogeny improves community phylogenetics of subtropical forests in China

Phylogenetic trees have been extensively used in community ecology. However, how the phylogeny construction affects ecological inferences is poorly understood. In this study, we constructed three different types of phylogenetic trees (a synthetic-tree generated using V.PhyloMaker, a barcode-tree generated using rbcL+matK+trnH-psbA, and a plastome-tree generated from plastid genomes) that represented an increasing level of phylogenetic resolution among 580 woody plant species from six forest dynamic plots in subtropical evergreen broadleaved forests of China. We then evaluated the performance of each phylogeny in estimations of community phylogenetic structure, turnover and phylogenetic signal in functional traits. As expected, the plastome-tree was most resolved and most supported for relationships among species. For local phylogenetic structure, the three trees showed consistent results with Faith's PD and MPD; however, only the synthetic-tree produced significant clustering patterns using MNTD for some plots. For phylogenetic turnover, contrasting results between the molecular trees and the synthetic-tree occurred only with nearest neighbor distance. The barcode-tree agreed more with the plastome-tree than the synthetic-tree for both phylogenetic structure and turnover. For functional traits, both the barcode-tree and plastome-tree detected phylogenetic signal in maximum height, but only the plastome-tree detected signal in leaf width. This is the first study that uses plastid genomes in large-scale community phylogenetics. Our results highlight the improvement of plastome-trees over barcode-trees and synthetic-trees for the analyses studied here. Our results also point to the possibility of type I and II errors in estimation of phylogenetic structure and turnover and detection of phylogenetic signal when using synthetic-trees.

Size dependent associations between tree diameter growth rates and functional traits in an Asian tropical seasonal rainforest

Many studies focus on the relationships between plant functional traits and tree growth performances. However, little is known about the ontogenetic shifts of the relationships between functional traits and tree growth. This study examined associations between stem and leaf functional traits and growth rates and their ontogenetic shifts across 20 tropical tree species in a tropical seasonal rainforest in Xishuangbanna, south-west China. For each species, physiological active branches of individual trees belonged to three size classes (i.e. small, diameter at breast height (DBH) 5-10 cm; middle, DBH 10-20 cm; big, DBH >20 cm) were sampled respectively. We measured 18 morphological and structural traits, which characterised plant hydraulic properties or leaf economic spectrum. Associations between diameter growth rates and functional traits were analysed across three size classes. Our results revealed that diameter growth rates of big-sized trees were mainly related to traits related to plant hydraulic efficiency (i.e. theoretical hydraulic conductivity (Ktheo) and leaf vein density (Dvein)), which suggests that the growth of large trees is limited mainly by their xylem water transport capacity. For middle-sized trees, growth rates were significantly related to traits representing leaf economic spectrum (i.e. specific leaf area (SLA), individual leaf mass (ILM), palisade thickness (PT) and spongy thickness (SP)). Diameter growth rates of small-sized trees were not correlated with hydraulic or leaf economic traits. Thus, the associations between tree growth rates and functional traits are size dependent. Our results suggest ontogenetic shift of functional traits which could potential contribute to different growth response to climate change.

[Effect of long-term deep slow-wave sleep deprivation on the reproductive system in male rats]

Objective: To investigate the effect of long-term deep slow-wave sleep deprivation on the gonad axis, sperm abnormality rate, and structure of the testis in male rats and possible mechanisms. Methods: A total of 30 specific pathogen-free male Wistar rats aged 5 weeks were randomly divided into slow-wave sleep deprivation group 1 (SD1 group) , slow-wave sleep and sleep time deprivation group 2 (SD2 group) , and control group, with 10 rats in each group. The flower pot method was used to establish a model of sleep deprivation. In addition to 12-hour sleep deprivation at night, the rats in the SD1 group were given interference once every 24 minutes, and those in the SD2 group were deprived of sleep for 8 minutes every 24 minutes; the rats in the control group were given 12-hour light illumination and then placed in dark environment for 12 hours. All rats were sacrificed by exsanguination from the femoral artery, and the testis, the epididymis, and blood were collected for analysis. Sperm abnormality rate and sperm motility rate were measured, and cauda epididymal sperm counting was performed. ELISA was used to measure the serum levels of testosterone (T) , follicle-stimulating hormone (FSH) , and luteinizing hormone (LH) . Results: Compared with the control group, the SD2 group had a significant increase in organ coefficient of the epididymis (P<0.05) and a significant reduction in sperm motility rate (P<0.05) . There were significant differences between the SD1 group and the SD2 group in the increase in sperm abnormality rate (P<0.05) and the reduction in cauda epididymal sperm count (P<0.05) . The levels of FSH and T tended to increase, and the level of LH tended to decrease. Pathological examination showed degeneration and vacuolization of a small amount of spermatogenic cells in the SD1 group; in the SD2 group, there were significant degeneration, edema, and vacuolization of most spermatogenic cells, some spermatogenic cells were observed in the lumen, and there were no sperms in the lumen. Conclusion: Long-term deep slow-wave sleep deprivation impairs the structure of the testis, affects sperm motility rate and sex hormones, and increases the risk of sperm abnormality.

Size-dependent oriented attachment in the growth of pure and defect-free hexagonal boron nitride nanocrystals

Pure and defect-free hexagonal boron nitride (hBN) nanocrystals with deep-ultraviolet light emissions at around 215 nm were prepared via a solid state reaction. This involved preparing a precursor from potassium borohydride and ammonium chloride powders, and then heating the precursor and additional ammonium chloride to 1000 °C within a nitrogen atmosphere. The hBN nanocrystals were studied using a variety of characterization techniques (e.g., TEM, AFM, N(2) absorption/desorption). A growth mechanism based on size-dependent oriented attachment was proposed for the nanocrystals.

The impact of iodine excess on thyroid hormone biosynthesis and metabolism in rats

Thyroid function ultimately depends on appropriate iodine supply to the gland. There is a complex series of checks and balances that the thyroid uses to control the orderly utilization of iodine for hormone synthesis. The aim of our study is to evaluate the mechanism underlying the effect of iodine excess on thyroid hormone metabolism. Based on the successful establishment of animal models of normal-iodine (NI) and different degrees of high-iodine (HI) intake in Wistar rats, the content of monoiodotyrosine (MIT), diiodotyrosine (DIT), T(4), and T(3) in thyroid tissues, the activity of thyroidal type 1 deiodinase (D1) and its (Dio1) mRNA expression level were measured. Results showed that, in the case of iodine excess, the biosynthesis of both MIT and DIT, especially DIT, was increased. There was an obvious tendency of decreasing in MIT/DIT ratio with increased doses of iodine intake. In addition, iodine excess greatly inhibited thyroidal D1 activity and mRNA expression. T(3) was greatly lower in the HI group, while there was no significant difference of T(4) compared with NI group. The T(3)/T(4) ratio was decreased in HI groups, antiparalleled with increased doses of iodine intakes. In conclusion, the increased biosyntheses of DIT relative to MIT and the inhibition of thyroidal Dio1 mRNA expression and D1 activity may be taken as an effective way to protect an organism from impairment caused by too much T(3). These observations provide new insights into the cellular regulation mechanism of thyroid hormones under physiological and pathological conditions.

Retrospective analysis of thyroid nodules by clinical and pathological characteristics, and ultrasonographically detected calcification correlated to thyroid carcinoma in South China

OBJECTIVE

To investigate the clinical and pathological characteristics of thyroid nodules, as well as to evaluate the significance of ultrasonographically detected thyroid calcification in the diagnosis of thyroid carcinomas.

METHODS

Retrospective data were studied from 1,051 consecutive patients who underwent a thyroidectomy in the Provincial Hospital of Fujian Medical University in South China between January 2003 and July 2006 for nodular thyroid disease. Complete sonographical information before surgery was only collected from 758 of the 1,051 patients.

RESULTS

Among the 1,051 patients, benign lesions were found in 857 (81.54%) patients, of whom 612 (71.41%) were nodular goiter; malignant lesions were found in 194 (18.46%) patients, in whom benign thyroid lesions were also found in 85 (43.81%) patients. A total of 48 patients suffered from microcarcinomas, of whom 37 patients had benign lesions; these 37 accounted for 43.53 and 77.08%, respectively, of the 85 malignant cases with benign lesions and the 48 cases with microcarcinomas. In the 758 patients who underwent thyroid ultrasonography before surgery, intrathyroidal calcifications were apparent in 243 patients (32.06%). The incidence of calcification was significantly higher in patients with thyroid carcinoma (54.17%) than in those with benign lesions (26.87%; p < 0.005). Detection of calcification in thyroid lesions by ultrasound had a sensitivity of 32.38% and a specificity of 87.35%, with an OR of 3.31 (95% CI, 2.24-4.63), positive likelihood ratio of 2.56, negative likelihood ratio of 0.77 and a kappa value of 0.23.

CONCLUSION

Thyroid carcinoma, especially microcarcinoma, often coexists with benign thyroid disease. Calcification detected by thyroid ultrasound represents a risk factor for malignancy, but is of limited use as a sole marker of malignancy.

[Effect of uncaria on evoked field potential of hippocampal slice in epileptogenic rat]

AIM

To investigate the effect of uncaria on evoked field potential of CA1 hippocampal slice in epileptogenic model.

METHODS

We made rats which were injected by pilocarpine as epileptic-models. The pathway of drug administration is titration adjacent to hippocampal slices. We recorded the evoked field potential of hippocampal slice by glass microelectrode extracellularly, and observed the effect of uncaria on the amplitude of population spike (PS) in CA1 pyramidal cells in hippocampal slices.

RESULTS

The uncaria with concentration of 1 g/ml could reduce the amplitude of PS in CA1 of hippocampal slices. The average of fall was 27.64%, and restored in 8.71 minutes on average (n = 14, P < 0.01).

CONCLUSION

Uncaria could reduce the amplitude of PS in CA1 of epileptic hippocampal slices remarkably. These results show that uncaria can inhabited the synaptic transfer activity of CNS remarkably, suggest that it has the distinct effect of anti-epilepsy.

Differential binding of (+) and (-) gossypol to plasma protein and their entry into rat testis

Concentrations of (+) and (-) gossypol were measured by high performance liquid chromatography after they were incubated with plasma proteins in vitro. The concentration of (-) gossypol decreased more than the concentration of (+) gossypol. A similar decrease in free gossypol concentrations in the blood plasma of rats was observed after intravenous infusion of gossypol enantiomers. The concentration of (-) gossypol was also found to be lower than the concentration of (+) gossypol at the blood-testis barrier. The biological effect of (-) gossypol probably results from its stereospecific binding to extra- and intracellular proteins in vivo and inhibition of the biological activity of some proteins.

Immunization strategies for the production of rat monoclonal anti-idiotope antibodies

Anti-idiotypic antibodies are powerful reagents for the study of immunoregulation, and have potential interest as vaccines against tumors and infectious diseases. Three immunization strategies for the production of rat monoclonal anti-idiotope antibodies have been compared in this paper. Male Wistar rats were immunized i.p. and at multiple subcutaneous sites with 750 micrograms of purified monoclonal antibody against Plasmodium falciparum for three times and subsequently boosted by (1) intraperitoneal injection with 750 micrograms of the immunogen, (2) intravenous inoculation with 400 micrograms of the IgG, and (3) intrasplenic immunization with 200 micrograms of the idiotype. With the intraperitoneal boost method, the frequency of hybrids with anti-idiotope activity was 0.3-0.9% with 62.8-85.2% of the seeded wells containing hybrids. In the intravenous boost group, the percentage of hybrids demonstrating anti-idiotope activity increased to 11.0-13.3% with 80.2-97.9% of the hybrid efficiency. When immunized by the intrasplenic boost route, the frequency of anti-idiotope hybrids generated rose to 12.9-16.4% with 82.3-96.6% of the hybrid efficiency. There was no obvious effect of the boost immunizing methods on the generation of rat monoclonal anti-mouse IgG antibodies. These results indicated that the multiple-site immunization followed by intravenous or intrasplenic boost injection was an appropriate immunizing method for the production of monoclonal anti-idiotope antibodies.