Drought resistance index screening and evaluation of lettuce under water deficit conditions on the basis of morphological and physiological differences

Introduction

Water is one of the important factors affecting the yield of leafy vegetables. Lettuce, as a widely planted vegetable, requires frequent irrigation due to its shallow taproot and high leaf evaporation rate. Therefore, screening drought-resistant genotypes is of great significance for lettuce production.

Methods

In the present study, significant variations were observed among 13 morphological and physiological traits of 42 lettuce genotypes under normal irrigation and water-deficient conditions.

Results

Frequency analysis showed that soluble protein (SP) was evenly distributed across six intervals. Principal component analysis (PCA) was conducted to transform the 13 indexes into four independent comprehensive indicators with a cumulative contribution ratio of 94.83%. The stepwise regression analysis showed that root surface area (RSA), root volume (RV), belowground dry weight (BDW), soluble sugar (SS), SP, and leaf relative water content (RWC) could be used to evaluate and predict the drought resistance of lettuce genotypes. Furthermore, the drought resistance ranks of the genotypes were similar according to the drought resistance comprehensive evaluation value (D value), comprehensive drought resistance coefficient (CDC), and weight drought resistance coefficient (WDC). The cluster analysis enabled the division of the 42 genotypes into five drought resistance groups; among them, variety Yidali151 was divided into group I as a strongly drought-resistant variety, group II included 6 drought-resistant genotypes, group III included 16 moderately drought-resistant genotypes, group IV included 12 drought-sensitive genotypes, and group V included 7 highly drought-sensitive genotypes. Moreover, a representative lettuce variety was selected from each of the five groups to verify its water resistance ability under water deficit conditions. In the drought-resistant variety, it was observed that stomatal density, superoxide anion (O2.-wfi2) production rate, and malondialdehyde (MDA) content exhibited a low increase rate, while catalase (CAT), superoxide dismutase (SOD), and that peroxidase (POD) activity exhibited a higher increase than in the drought-sensitive variety.

Discussion

In summary, the identified genotypes are important because their drought-resistant traits can be used in future drought-resistant lettuce breeding programs and water-efficient cultivation.

Drought Stress Tolerance in Vegetables: The Functional Role of Structural Features, Key Gene Pathways, and Exogenous Hormones

The deleterious effects of drought stress have led to a significant decline in vegetable production, ultimately affecting food security. After sensing drought stress signals, vegetables prompt multifaceted response measures, eventually leading to changes in internal cell structure and external morphology. Among them, it is important to highlight that the changes, including changes in physiological metabolism, signal transduction, key genes, and hormone regulation, significantly influence drought stress tolerance in vegetables. This article elaborates on vegetable stress tolerance, focusing on structural adaptations, key genes, drought stress signaling transduction pathways, osmotic adjustments, and antioxidants. At the same time, the mechanisms of exogenous hormones such as abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), and ethylene (ET) toward improving the adaptive drought tolerance of vegetables were also reviewed. These insights can enhance the understanding of vegetable drought tolerance, supporting vegetable tolerance enhancement by cultivation technology improvements under changing climatic conditions, which provides theoretical support and technical reference for innovative vegetable stress tolerance breeding and food security.

Transcriptome analysis reveals that auxin promotes strigolactone-induced adventitious root growth in the hypocotyl of melon seedlings

Introduction

Strigolactone (SL) and auxin are two important phytohormones involved in plant root development, but whether they show synergistic or mutual promotion effects during adventitious root (AR) formation has not been adequately explored.

Methods

In this study, we investigated the mechanisms of GR24 (synthetic SL) and indole-3-acetic acid (IAA; a type of auxin) in the formation of ARs using melon as the study material.

Results

Morphological measurements showed that the AR number, length, superficial area, and volume under the GR24 treatment were 1.60-3.27, 1.58-3.99, 2.06-3.42, and 3.00-6.11 times greater than those of the control group, respectively, at 6-10 days; the GR24+IAA treatment further promoted AR formation in melon seedlings, and the AR number, length, superficial area, and volume under the GR24+IAA treatment were 1.44-1.51, 1.28-1.73, 1.19-1.83, and 1.31-1.87 times greater than those obtained with the GR24 treatment, respectively. Transcriptome analysis revealed 2,742, 3,352, and 2,321 differentially expressed genes (DEGs) identified from the GR24 vs. control, GR24+IAA vs. control, and GR24+IAA vs. GR24 comparisons, respectively. The GR24 treatment and GR24+IAA treatment affected auxin and SL synthesis as well as components of the phytohormone signal transduction pathway, such as auxin, brassinosteroid (BR), ethylene (ETH), cytokinin (CK), gibberellin (GA), and abscisic acid (ABA). The concentrations of auxin, GA, zeatin (ZT), and ABA were evaluated using high-performance liquid chromatography (HPLC). From 6 to 10 days, the auxin, GA, and ZT contents in the GR24 treatment group were increased by 11.48%-15.34%, 11.83%-19.50%, and 22.52%-66.17%, respectively, compared to the control group, and these features were increased by 22.00%-31.20%, 21.29%-25.75%, 51.76%-98.96%, respectively, in the GR24+IAA treatment group compared with the control group. Compared to that in the control, the ABA content decreased by 10.30%-11.83% in the GR24 treatment group and decreased by 18.78%-24.00% in the GR24+IAA treatment group at 6-10 days.

Discussion

Our study revealed an interaction between strigolactone and auxin in the induction of AR formation in melon seedlings by affecting the expression of genes related to plant hormone pathways and contents.

Transcriptome analysis showed that tomato-rootstock enhanced salt tolerance of grafted seedlings was accompanied by multiple metabolic processes and gene differences

Introduction

Grafting is a commonly used cultural practice to counteract salt stress and is especially important for vegetable production. However, it is not clear which metabolic processes and genes are involved in the response of tomato rootstocks to salt stress.

Methods

To elucidate the regulatory mechanism through which grafting enhances salt tolerance, we first evaluated the salt damage index, electrolyte permeability and Na⁺ accumulation in tomato (Solanum lycopersicum L.) leaves of grafted seedlings (GSs) and nongrafted seedlings (NGSs) subjected to 175 mmol·L^{- 1} NaCl for 0-96 h, covering the front, middle and rear ranges.

Results

Compared with the NGS, the GSs were more salt tolerant, and the Na⁺ content in the leaves decreased significantly. Through transcriptome sequencing data analysis of 36 samples, we found that GSs exhibited more stable gene expression patterns, with a lower number of DEGs. WRKY and PosF21 transcription factors were significantly upregulated in the GSs compared to the NGSs. Moreover, the GSs presented more amino acids, a higher photosynthetic index and a higher content of growth-promoting hormones. The main differences between GSs and NGSs were in the expression levels of genes involved in the BR signaling pathway, with significant upregulation of XTHs. The above results show that the metabolic pathways of "photosynthetic antenna protein", "amino acid biosynthesis" and "plant hormone signal transduction" participate in the salt tolerance response of grafted seedlings at different stages of salt stress, maintaining the stability of the photosynthetic system and increasing the contents of amino acids and growth-promoting hormones (especially BRs). In this process, the transcription factors WRKYs, PosF21 and XTHs might play an important role at the molecular level.

Discussion

The results of this study demonstrates that grafting on salt tolerant rootstocks can bring different metabolic processes and transcription levels changes to scion leaves, thereby the scion leaves show stronger salt tolerance. This information provides new insight into the mechanism underlying tolerance to salt stress regulation and provides useful molecular biological basis for improving plant salt resistance.

GABA Metabolism, Transport and Their Roles and Mechanisms in the Regulation of Abiotic Stress (Hypoxia, Salt, Drought) Resistance in Plants

γ- Aminobutyric acid (GABA) is a ubiquitous four-carbon non-protein amino acid. In plants, GABA is found in different cell compartments and performs different metabolic functions. As a signalling molecule, GABA participates in the regulation of tolerance to various abiotic stresses. Many research studies have found that GABA accumulates in large amounts when plants are subjected to abiotic stress, which have been demonstrated through the Web of Science, PubMed, Elsevier and other databases. GABA enhances the tolerance of plants to abiotic stress by regulating intracellular pH, ion transport, activating antioxidant systems and scavenging active oxygen species. In the process of GABA playing its role, transport is very important for the accumulation and metabolism pathway of GABA in cells. Therefore, the research on the transport of GABA across the cell membrane and the organelle membrane by transport proteins is a direction worthy of attention. This paper describes the distribution, biosynthesis and catabolism of GABA in plants. In addition, we focus on the latest progress in research on the transport of exogenous GABA and on the function and mechanism in the regulation of the abiotic stress response. Based on this summary of the role of GABA in the resistance to various abiotic stresses, we conclude that GABA has become an effective compound for improving plant abiotic tolerance.

Review of the Mechanisms by Which Transcription Factors and Exogenous Substances Regulate ROS Metabolism under Abiotic Stress

Reactive oxygen species (ROS) are signaling molecules that regulate many biological processes in plants. However, excess ROS induced by biotic and abiotic stresses can destroy biological macromolecules and cause oxidative damage to plants. As the global environment continues to deteriorate, plants inevitably experience abiotic stress. Therefore, in-depth exploration of ROS metabolism and an improved understanding of its regulatory mechanisms are of great importance for regulating cultivated plant growth and developing cultivars that are resilient to abiotic stresses. This review presents current research on the generation and scavenging of ROS in plants and summarizes recent progress in elucidating transcription factor-mediated regulation of ROS metabolism. Most importantly, the effects of applying exogenous substances on ROS metabolism and the potential regulatory mechanisms at play under abiotic stress are summarized. Given the important role of ROS in plants and other organisms, our findings provide insights for optimizing cultivation patterns and for improving plant stress tolerance and growth regulation.

Detection and Quantification of Fusarium oxysporum f. sp. niveum Race 1 in Plants and Soil by Real-time PCR

Fusarium wilt caused by Fusarium oxysporum f. sp. niveum (Fon) is the most serious soil-borne disease in the world and has become the main limiting factor of watermelon production. Reliable and quick detection and quantification of Fon are essential in the early stages of infection for control of watermelon Fusarium wilt. Traditional detection and identification tests are laborious and cannot efficiently quantify Fon isolates. In this work, a real-time polymerase chain reaction (PCR) assay has been described to accurately identify and quantify Fon in watermelon plants and soil. The FONRT-18 specific primer set which was designed based on identified specific sequence amplified a specific 172 bp band from Fon and no amplification from the other formae speciales of Fusarium oxysporum tested. The detection limits with primers were 1.26 pg/µl genomic DNA of Fon, 0.2 pg/ng total plant DNA in inoculated plant, and 50 conidia/g soil. The PCR assay could also evaluate the relationships between the disease index and Fon DNA quantity in watermelon plants and soil. The assay was further used to estimate the Fon content in soil after disinfection with CaCN2. The real-time PCR method is rapid, accurate and reliable for monitoring and quantification analysis of Fon in watermelon plants and soil. It can be applied to the study of disease diagnosis, plant-pathogen interactions, and effective management.

Gamma-aminobutyric acid (GABA) alleviates salt damage in tomato by modulating Na+ uptake, the GAD gene, amino acid synthesis and reactive oxygen species metabolism

BACKGROUND

Salt stress is a serious abiotic stress that caused crop growth inhibition and yield decline. Previous studies have reported on the the synthesis of gamma-aminobutyric acid (GABA) and its relationship with plant resistance under various abiotic stress. However, the relationship between exogenous GABA alleviating plant salt stress damage and ion flux, amino acid synthesis, and key enzyme expression remains largely unclear. We investigated plant growth, Na⁺ transportation and accumulation, reactive oxygen species (ROS) metabolism and evaluated the effect of GABA on amino acids, especially SlGADs gene expression and the endogenous GABA content of tomato (Solanum lycopersicum L.) seedlings treated with or without 5 mmol·L^- 1 GABA under 175 mmol·L^- 1 NaCl stress.

RESULTS

Exogenous application of GABA significantly reduced the salt damage index and increased plant height, chlorophyll content and the dry and fresh weights of tomato plants exposed to NaCl stress. GABA significantly reduced Na⁺ accumulation in leaves and roots by preventing Na⁺ influx in roots and transportation to leaves. The transcriptional expression of SlGAD1-3 genes were induced by NaCl stress especially with GABA application. Among them, SlGAD1 expression was the most sensitive and contributed the most to the increase in glutamate decarboxylase (GAD) activity induced by NaCl and GABA application; Exogenous GABA increased GAD activity and amino acid contents in tomato leaves compared with the levels under NaCl stress alone, especially the levels of endogenous GABA, proline, glutamate and eight other amino acids. These results indicated that SlGADs transcriptional expression played an important role in tomato plant resistance to NaCl stress with GABA application by enhancing GAD activity and amino acid contents. GABA significantly alleviated the active oxygen-related injury of leaves under NaCl stress by increasing the activities of antioxidant enzymes and decreasing the contents of active oxygen species and malondialdehyde.

CONCLUSION

Exogenous GABA had a positive effect on the resistance of tomato seedlings to salt stress, which was closely associated with reducing Na⁺ flux from root to leaves, increasing amino acid content and strengthening antioxidant metabolism. Endogenous GABA content was induced by salt and exogenous GABA at both the transcriptional and metabolic levels.

[Effects of arbuscular mycorrhizal fungi on the growth and fruit quality of plastic greenhouse Cucumis sativus L]

In this paper, arbuscular mycorrhizal fungi (AMF) Glomus versiforme (GV), Glomus mosseae (GM), Glomus intraradices (GI) and their mixtures were applied to inoculate plastic greenhouse Cucumis sativus seedlings to investigate the effects of AMF on C. sativus growth, development, yield, and quality. The results showed that all test AMF could form mycorrhiza with cucumber roots, and the infected rate reached 41.74% - 55.69%. Compared with the control, treatments GV, GM, GM + GV, GM + GV + GI and GV + GI enhanced the healthy seedling index by 58.14% - 123.6%, and increased early yield by 21.71% - 37.87% and total yield by 19.72% - 34.41%. AMF also improved fruit quality. The Vc content of cucumber fruit increased by 22.84% and 21.95% in treatments GM + GV and GV + GI, soluble sugar content increased by 13.29%, 8.25%, and 10.20% in treatments GV, GI and GV + GI, and amino acid content increased by 47.66% and 23.19% in treatments GV and GM + GI, respectively, while soluble protein content increased by 17.67% - 34.29% in all AMF treatments. The results suggested that AMF inoculation could significantly promote the seedling growth of cucumber and improve its fruit quality, and the effects differed with different AMF and their combinations.

[Application of RF-II pedicle screw system in lumbar spondylolisthesis]

Thirty-eight patients with isthmic(31 cases), degenerative(6 cases), and post-traumatic(1 case) spondylolisthesis were treated with RF-II pedicle screw system. Eighteen patients were classified as Degree I lesion, 14 as Degree II lesion, and 6 as Degree III lesion. Postoperatively, 34 cases(90%) obtained an anatomical improvement obviously. The percentage of the patients who got excellent and good recovery was above 90%. We conclude that RF-II pedicle screw fixation system has the strongest three-dimensional rigidity and, attains complete and satisfactory decompression. The entire intervertebral disk in the level of the lesion is suggested to be removed. The system is ingeniously and originally designed, and is easy to obtain a simple and an effective reduction of the spondylolisthesis. Additionally, the application of the system can obtain a good interbody fusion by three steps: broadening the interbody space; stuffing the space with broken bones; and compressing the involved vertebral body. The authors considered that the RF-II screw system is one of the most ideal internal fixations for the treatment of lumbar spondylolisthesis.

Clinical significance of examining IL-2R in peripheral blood lymphocytes of patients with gastric cancer

OBJECTIVE

To understand the clinical significance of membrane receptors of interleukin-2 (CD25) in peripheral blood lymphocytes (PBL) of patients with gastric cancer.

METHODS

CD25 percentages in PBL from 110 patients with gastric cancer and 100 normal individuals were examined by flow cytometry. Results were analyzed clinically and pathologically.

RESULTS

Mean CD25% in PBL from normal individuals and patients with gastric cancer were 17.24 +/- 5.33 and 22.47 +/- 6.82, respectively, and the difference was significant (P < 0.01). Abnormally elevated CD25% in PBL from patients with gastric cancer were correlated with tumor site, macropathology type, tumor size, differentiation degree and clinical stage.

CONCLUSION

Measuring CD25% in PBL from gastric cancer patients before surgery may provide a reference for diagnosis, immune treatment and judging prognosis.

[The effects of ethanol on neuromuscular junctions of adult toad]

OBJECTIVE

To investigate the effects of ethanol on the transmission at the neuromuscular junctions(NMJ) and the possible mechanism thereby.

METHODS

The effects of ethanol on the endplate potential (EPP) and miniature endplate potential(MEPP) of sciatic nerve-sartorious muscle preparations of 20 adult toads (Bufo bufo gargarizans) were studied in vitro by means of intracellular microelectrode recording.

RESULTS

Ethanol could cause the changes in EPP amplitude so as to influence the transmission at NMJ, and the effects apparently depended on the concentration of the ethanol. A proper concentration of ethanol could produce a significant increase in EPP amplitude and therefore facilitate the transmission at the NMJ. A proper concentration of ethanol also could produce a significant increase in MEPP frequency but had no influence on MEPP amplitude.

CONCLUSION

Ethanol can increase the quantal number of transmitters released from presynaptic part. That may be one of the reasons why ethanol can facilitate the transmission at the NMJ.

A study of Hodgkin/Reed-Sternberg cells using single cell polymerase chain reaction

OBJECTIVE

To investigate the characteristics of Hodgkin/Reed-Stemberg (H/R-S) cells found in patients with various types of Hodgkin's disease (HD).

METHODS

H/R-S cells were micropicked from frozen sections of tissues affected by HD. The DNA from these cells was amplified by polymerase chain reaction (PCR) using immunoglobulin heavy chain gene FR III a/JH primers and light chain gene family-specific primers.

RESULTS

A total of 52/135 (35.8%) isolated cells showed the specific products in the reactions. IgH and V kappa 4 rearrangements were repeatedly found in many cells from a lymphocyte predominance type sample; repeated V kappa 4 and individual IgH/V kappa 2,4 rearrangements and individual IgH, V lambda 3/ V kappa 4 rearrangements were found in two different cases of the nodular sclerosis type; repeated IgH/ V lambda 3 and individual V lambda 2,4 rearrangements, repeated V kappa 2,4 rearrangements, repeated V kappa 4 and individual IgH/ V kappa 3 rearrangements, repeated IgH and individual V kappa 3/ V lambda 4 rearrangements were detected in 3 cases of the mixed cellularity type. Repeated and individual IgH rearrangements were found in other 2 cases.

CONCLUSION

The H/R-S cells isolated from the lymphocyte predominance subtypes of HD have IgH and V lambda 4 gene rearrangements. This suggests that the lymphocyte predominance type is a proliferation of neoplastic B cells. The cells isolated from the mixed cellularity and nodular sclerosis types derive from B lineage cells at various stages of differentiation because of the presence of their IgH, kappa and/or lambda gene rearrangements. To our knowledge, this is the first time that the lambda gene rearrangement was detected in H/R-S cells.

[Multiple tumor suppressor 1/p16 gene alterations in human esophageal squamous-cell carcinoma: clinical significance and regional difference]

OBJECTIVE

To further understand multiple tumor suppressor 1/p16 (mts1/p16) gene alterations in squamous-cell esophageal carcinoma (EC) in relation to its biologic behavior and regional difference.

METHODS

Samples of human EC from 92 patients residing in Zhejiang province and in Linxian, Henan province were analyzed for the expression, mutation and deletion of the multiple tumor suppressor gene (mts1/p16) by immunohistochemical staining, polymerase chain reaction and single strand conformation polymorphism.

RESULTS

mts1/p16 expression at protein level was demonstrated in 44 cases (47.8%). Gene deletion was detected in 22 cases (23.9%) and point mutation in 5 cases (5.4%). Expression of mst1/p16 showed significant correlation with pathologic staging, lymph node status and survival. However, deletion of mst1/p16 did not show correlation with the clinico-pathologic parameters. EC patients in stage T2 from Linxian had significantly lower rate of mst1/p16 protein expression compared to those from Zhejiang province at the same time period. Moreover, there was close association between gene alterations (mutation + deletion) and frequency of lymph node metastasis in Zhejiang EC patients. No such association was observed in EC patients from Linxian.

CONCLUSION

msts1/p16 gene alteration is a common genetic event in the carcinogenesis and progression of human esophageal cancer. EC patients from two different regions present differential alterations in mst1/p16 gene.

[Effect of ATP on malignant phenotype of a human gastric cancer cell line]

OBJECTIVE

To study the effect of ATP on proliferation and differentiation of a human gastric cancer cell line.

METHODS

M17, a subclone of human gastric cancer cell line MGC-803, was treated in vitro with ATP(0.23 mg/ml). After 48 hr, the following parameters were examined. (1) Proliferation of cells by daily cell counting. (2) Microvilli of the cells were observed by scanning EM. (3) Gap junction intercellular communication was examined by mechanical scraping and Lucifer dye transfer. (4) Microfilament of the cytoskeleton was studied with fluorescin-labeled phalloidin. (5) Vinculin adhesion plague was stained immunocytochemically with monoclonal antibodies.

RESULTS

ATP significantly inhibited the in vitro growth of M17 cells. The ATP-treated M17 cells showed disappearance of microvilli on the cell surface, increased gap junction intercellular communication, improved organization of microfilament bundles and reappearance of vinculin adhesion plagues.

CONCLUSION

ATP not only inhibits proliferation but also induces differentiation of a human gastric cancer cell line with reversion from malignant toward normal phenotype. The parameters examined could serve as useful biomarkers of human gastric cancer.

Hodgkin's disease: immunoglobulin heavy and light chain gene rearrangements revealed in single Hodgkin/Reed-Sternberg cells

AIM

To corroborate and investigate the nature of Hodgkin/Reed-Sternberg cells (H/R-S) of various subtypes of Hodgkin's disease.

METHOD

Single H/R-S cells were micro-picked from frozen sections of tissues affected by Hodgkin's disease. The DNA from these cells was amplified by the polymerase chain reaction (PCR) with immunoglobulin heavy chain (IgH) gene FRIIIa/JH primers and light chain gene family specific primers.

RESULTS

Fifty two of 135 isolated cells gave specific reaction products (36%). IgH and V kappa 4 gene rearrangements were found repeatedly in many H/R-S cells from one case of lymphocyte predominant Hodgkin's disease. Repeated V kappa 4 and individual IgH/V kappa 4,2 rearrangements were seen in one case, and individual IgH and V lambda 3/V kappa 4 rearrangements were seen in another case of nodular sclerosis-type Hodgkin's disease. Repeated IgH/V lambda 3 and individual V lambda 2,4 rearrangements, repeated V kappa 4 and individual IgH/V kappa 3 rearrangements, and repeated IgH and individual V kappa 3/V kappa 4 rearrangement were detected, respectively, in three cases of mixed cellularity-type Hodgkin's disease. Repeated and individual IgH rearrangements were found in another two cases of mixed cellularity-type Hodgkin's disease.

CONCLUSION

The H/R-S cells isolated from lymphocyte predominant Hodgkin's disease had IgH and V kappa 4 gene rearrangements, which supports the conclusion that this disease results from a proliferation of neoplastic B cells. The IgH and kappa and/or lambda gene rearrangements seen in H/R-S cells isolated from classic Hodgkin's disease (mixed cellularity-type and nodular sclerosis-type) support the theory that these cells derive from B lineage cells at various stages of differentiation. To our knowledge, this is first time that lambda gene rearrangements have been detected in H/R-S cells.

[The effects of Tripterygium wilfordii polyglycosidium on neuromuscular junctions of adult toad]

The effects of tripterygium wilfordii polyglycosidium (TWP) on the transmission at the neuromuscular junctions (NMJ) of sciatic nerve-sartorius muscle preparations of 20 adult toads (Bufo bufo gargarizans) in vitro were studied by means of intracellular microelectrode recording of endplate potentials (EPP). The results revealed that TWP could cause changes of EPP amplitude so as to influence the transmission at NMJ, and the effects apparently depended on the concentration of the drug. A proper concentration of TWP could produce a significant increase in EPP amplitude and therefore facilitate the transmission at the NMJ.

[Effects of estrone on transmission at neuromuscular junction of the toad]

The effects of estrone on neuromuscular transmission were studied intracellularly at the muscle fiber endplate in isolated sciatic nerve-sartorius muscle preparations of the toad (Bufo bufo gargarizans) in vitro. The results showed that estrone (10(-4) mol/L), added to bath medium, caused an increase in amplitudes of endplate potentials (EPP) both in 10 micrograms tubocurarine treated and 10 mmol/L MgCl2 treated preparations, but the increase was more prominent in the former, and that estrone, 30 min after being added to bath medium, caused clear increase both in frequency and amplitude of miniature endplate potentials (MEPP), but the wave form of MEPP remained unchanged and the resting membrane potentials were also unchanged. These results suggest that estrone can increase neuromuscular transmission, which seems to involve primarily the presynaptic mechanism.

[A preliminary study on the hormonal causes of seasonal change in miniature endplate potentials at the neuromuscular junctions of the toad]

The hormonal causes of seasonal change in amplitudes of miniature endplate potentials (MEPP) in the adult toad (Bufo bufo gargarizans) were studied with intracellular recordings of MEPP at the neuromuscular junction of sartorius muscle fiber in vitro by adding L-thyroxine sodium and estrone to the bath medium during spring and autumn respectively. The results showed that L-thyroxine sodium (50 mumol/ L) could not change the amplitude of MEPP, regardless of spring or autumn, but estrone (100 mumol/L) could cause a clear increase in MEPP amplitude in both seasons. From these results it was presumed that thyroxine might be less related to the seasonal changes in MEPP amplitude whereas the seasonal fluctuations of gonadal hormones in the body might play a role.

[Seasonal variation and circannual rhythm of miniature end-plate potentials recorded from the neuromuscular junctions of the adult toad (Bufo bufo gargarizans)]

The seasonal variations and circannual rhythm of miniature end-plate potentials (MEPP) recorded from the sartorius neuromuscular junctions (NMJ) of 66 female and 62 male adult toads (Bufo bufo gargarizans) were studied with intracellular microelectrode recording techniques of electrophysiology. The results revealed that the mean amplitude of MEPP in each month of a year showed clear seasonal variation with a nadir in September and October and a zenith in March and April. This seasonal variation in MEPP amplitude was proved to be a circannual rhythm by single cosinor analysis and zero amplitude test, and the three parameters of the rhythm, i.e. mesor, amplitude and acrophase were 0.29 +/- 0.05 mV, 0.25 mV and -97.17 degrees in female toad and 0.19 +/- 0.02 mV, 0.16 mV and -92.01 degrees in male toad, respectively; the circannual rhythm in female toad was more distinct than that in male. Neither seasonal variation nor circannual rhythm was statistically significant in the changes of frequency of MEPP, regardless of toad sexuality.

[The changes of glucocorticoid receptor and beta-adrenoreceptor of lung tissues in SD rat asthma models and the effects of antiasthmatics on them]

OBJECTIVE

To observe the changes of glucocorticoid receptor (GR) and beta-adrenoreceptor (beta-AR) of lung tissue and the effects of oral procaterol, salbutamol and intraperitoneal (i.p.) or inhaled (i.h.) dexamethasone (Dex).

METHOD

The GR or beta-AR were determined by using 3H-dexamethasone and 3H-Dihydroalprenolol as ligand respectively, in groups of rat asthma models at 1, 3, 7, 14th day and groups received antiasthmatics on the 7th day after daily consecutive challenges.

RESULTS

The GR Bmax of asthma groups increased significantly after the first challenge, but decreased since the third day to a lower level than that of healthy control. The KD also decreased significantly since the third day. The beta-AR Bmax of asthma group gradually decreased to a significant low level on the 14th day. The Dex i.p. group had the lowest GR Bmax and the Dex i.h. group had the highest beta-AR Bmax among the treated. In the procaterol and salbutamol group, there had no decrease of GR Bmax compared with that of controls.

CONCLUSIONS

The GR and beta-AR levels of lung tissues changed after daily challenges. The GC played a down-regulation role on GR and an up-regulation role on beta-AR in lung tissues. The Dex i.h. had more advantages than Dex i.p. in terms of GR and beta-AR regulations.

Intraoperative thrombolytic treatment of microarterial occlusion by selective rt-PA infusion

The development of microvascular thrombosis during replantation surgery or free-flap transfer is generally best treated by identification of the problem, vascular revision, and reanastomosis. It is not unique, however, that surgical measures alone are insufficient or undesirable. Pharmacologic adjuncts are widely used for the prevention and sometimes treatment of microvascular thrombosis in surgical practice, but the benefit of thrombolytic agents, effective in dissolving an already established thrombus, is usually considered counterlevered by the fear of uncontrollable bleeding. However, selective infusion of the drug reduces the risk for systemic complications considerably and may therefore be considered in peripheral microvascular reconstruction. The technique was used successfully in a case of digital revascularization, where an arterial thrombosis was dissolved with the use of recombinant tissue plasminogen activator (rt-PA).