Foundation metrics for evaluating effectiveness of healthcare conversations powered by generative AI.

Generative Artificial Intelligence is set to revolutionize healthcare delivery by transforming traditional patient care into a more personalized, efficient, and proactive process. Chatbots, serving as interactive conversational models, will probably drive this patient-centered transformation in healthcare. Through the provision of various services, including diagnosis, personalized lifestyle recommendations, dynamic scheduling of follow-ups, and mental health support, the objective is to substantially augment patient health outcomes, all the while mitigating the workload burden on healthcare providers. The life-critical nature of healthcare applications necessitates establishing a unified and comprehensive set of evaluation metrics for conversational models. Existing evaluation metrics proposed for various generic large language models (LLMs) demonstrate a lack of comprehension regarding medical and health concepts and their significance in promoting patients' well-being. Moreover, these metrics neglect pivotal user-centered aspects, including trust-building, ethics, personalization, empathy, user comprehension, and emotional support. The purpose of this paper is to explore state-of-the-art LLM-based evaluation metrics that are specifically applicable to the assessment of interactive conversational models in healthcare. Subsequently, we present a comprehensive set of evaluation metrics designed to thoroughly assess the performance of healthcare chatbots from an end-user perspective. These metrics encompass an evaluation of language processing abilities, impact on real-world clinical tasks, and effectiveness in user-interactive conversations. Finally, we engage in a discussion concerning the challenges associated with defining and implementing these metrics, with particular emphasis on confounding factors such as the target audience, evaluation methods, and prompt techniques involved in the evaluation process.

USE-Evaluator: Performance metrics for medical image segmentation models supervised by uncertain, small or empty reference annotations in neuroimaging.

Performance metrics for medical image segmentation models are used to measure the agreement between the reference annotation and the predicted segmentation. Usually, overlap metrics, such as the Dice, are used as a metric to evaluate the performance of these models in order for results to be comparable. However, there is a mismatch between the distributions of cases and the difficulty level of segmentation tasks in public data sets compared to clinical practice. Common metrics used to assess performance fail to capture the impact of this mismatch, particularly when dealing with datasets in clinical settings that involve challenging segmentation tasks, pathologies with low signal, and reference annotations that are uncertain, small, or empty. Limitations of common metrics may result in ineffective machine learning research in designing and optimizing models. To effectively evaluate the clinical value of such models, it is essential to consider factors such as the uncertainty associated with reference annotations, the ability to accurately measure performance regardless of the size of the reference annotation volume, and the classification of cases where reference annotations are empty. We study how uncertain, small, and empty reference annotations influence the value of metrics on a stroke in-house data set regardless of the model. We examine metrics behavior on the predictions of a standard deep learning framework in order to identify suitable metrics in such a setting. We compare our results to the BRATS 2019 and Spinal Cord public data sets. We show how uncertain, small, or empty reference annotations require a rethinking of the evaluation. The evaluation code was released to encourage further analysis of this topic https://github.com/SophieOstmeier/UncertainSmallEmpty.git.

Non-inferiority of deep learning ischemic stroke segmentation on non-contrast CT within 16-hours compared to expert neuroradiologists.

We determined if a convolutional neural network (CNN) deep learning model can accurately segment acute ischemic changes on non-contrast CT compared to neuroradiologists. Non-contrast CT (NCCT) examinations from 232 acute ischemic stroke patients who were enrolled in the DEFUSE 3 trial were included in this study. Three experienced neuroradiologists independently segmented hypodensity that reflected the ischemic core on each scan. The neuroradiologist with the most experience (expert A) served as the ground truth for deep learning model training. Two additional neuroradiologists' (experts B and C) segmentations were used for data testing. The 232 studies were randomly split into training and test sets. The training set was further randomly divided into 5 folds with training and validation sets. A 3-dimensional CNN architecture was trained and optimized to predict the segmentations of expert A from NCCT. The performance of the model was assessed using a set of volume, overlap, and distance metrics using non-inferiority thresholds of 20%, 3 ml, and 3 mm, respectively. The optimized model trained on expert A was compared to test experts B and C. We used a one-sided Wilcoxon signed-rank test to test for the non-inferiority of the model-expert compared to the inter-expert agreement. The final model performance for the ischemic core segmentation task reached a performance of 0.46 ± 0.09 Surface Dice at Tolerance 5mm and 0.47 ± 0.13 Dice when trained on expert A. Compared to the two test neuroradiologists the model-expert agreement was non-inferior to the inter-expert agreement, [Formula: see text]. The before, CNN accurately delineates the hypodense ischemic core on NCCT in acute ischemic stroke patients with an accuracy comparable to neuroradiologists.

Regulation of Hypnotic Active Components of Cnidii Fructus on Melatonin Synthesis Rate-limiting Enzyme AANAT in Rats with PCPA-induced Insomnia / 中国实验方剂学杂志

Objective:To observe the effects of Cnidii Fructus hypnotic active components （CHC） on the behaviors of rats with p-chlorophenylalanine （PCPA）-induced insomnia and melatonin （MT） synthesis rate-limiting enzyme arylalkylamine <italic>N</italic>-acetyltransferase （AANAT）， and explore the protective mechanism of CHC on the pineal gland. Method:Male SD rats of SPF grade were randomly divided into a blank control group， a model group， a MT group， and high-， medium-， and low-dose CHC groups with 10 rats in each group. Except for the blank control group， other groups received 4.5% PCPA suspension at 10 mL·kg^-1， intragastric administration， for two consecutive days. After PCPA model of insomnia was established， normal and model groups were gavaged at the same volume of 2% Tween-80， MT control group （10 mg·kg^-1）， CHC was high， medium and low （60， 30， 15 mg·kg^-1）， 10 mL·kg^-1， once a day， for consecutive 7 days. Four days after administration， open field， elevated cross maze， and pentobarbital sodium-induced sleep tests were conducted， respectively. Serum MT was detected by enzyme-linked immunosorbent assay. The mRNA expression level of AANAT was determined by real-time fluorescence-based quantitative polymerase chain reaction （Real-time PCR）. The expression of AANAT protein in the pineal gland was detected by Western blot. Result:Compared with the results in the blank control group， the total distance of open field activity and standing times and duration in the central area were increased （<italic>P</italic><0.05， <italic>P</italic><0.01）， the proportions of open arm entry （OE%） and open arm time （OT%） were decreased （<italic>P</italic><0.05）， and the sleep latency was prolonged （<italic>P</italic><0.01） in the model group. Compared with the model group， no significant difference was observed in the low-dose CHC group， while other groups exhibited reduced total distance of activity （<italic>P</italic><0.05， <italic>P</italic><0.01）， elevated OE% （<italic>P</italic><0.05）， shortened sleep latency， and prolonged sleep time （<italic>P</italic><0.05， <italic>P</italic><0.01）. Compared with the serum MT in the blank control group， that in the model group was decreased （<italic>P</italic><0.01）. Compared with the model group， no significant difference was observed in the low-dose CHC group， while other groups displayed increased serum MT （<italic>P</italic><0.05）. The mRNA and protein expression of AANAT was decreased in the model group as compared with that in the blank control group （<italic>P</italic><0.01）. Compared with the model group， the MT group and the high-dose CHC group showed up-regulated expression （<italic>P</italic><0.05）. Conclusion:CHC improved the behavioral indexes of PCPA-induced insomnia， increased the synthesis and secretion of MT in pineal cells， and elevated the serum MT level， which was related to the up-regulation of the mRNA and protein expression of AANAT in the pineal gland.

Serum exosomes of rats with hepatic ischemia-reperfusion injury induce the damage of hippocampus and cerebral cortex / 生理学报

The paper was aimed to explore the role of serum exosomes induced by hepatic ischemia/reperfusion (I/R) injury in the damage of hippocampus and cerebral cortex of rats. The male Sprague-Dawley (SD) rats were randomly divided into 4 groups: sham operation group (S), hepatic I/R injury group (I/R), serum exosomes from S group treatment group (ES) and serum exosomes from I/R group treatment group (EI). In ES group and EI group, 100 μL serum exosomes from S group and I/R group were injected into the normal rats through tail vein respectively. Another three normal rats were injected intravenously with serum exosomes labeled with PKH26 red fluorescence, and then the expression of fluorescence in the brain tissues was observed by immunofluorescence microscope. The morphology and size of exosomes were observed by transmission electron microscope, the expression of exosomes markers CD63 and CD9 was detected by Western blot, and the damage of liver and brain, levels of apoptosis and oxidative stress response in hippocampus and cerebral cortex were observed by serological and histological indexes. The results showed that the exosomes were a group of round or ovoid membranous vesicles, sized in 30-100 nm. Compared with that in S group, the content of serum exosomes in I/R group was increased (P < 0.05). Moreover, serum exosomes could go through the blood-brain barrier and enter the brain tissue freely through blood circulation. The index of liver function in I/R group was significantly higher than that in S group (P < 0.05). There was no significance in the degree of brain damage, apoptosis and oxidative stress in hippocampus and cerebral cortex between S group and ES group. Compared with those in S group and ES group, the serum levels of brain injury markers, apoptosis index (AI) and oxidative stress in hippocampus and cerebral cortex increased in I/R group and EI group (P < 0.05). Whereas, compared with those in I/R group, the above indicators in EI group decreased (P < 0.05). Therefore, hepatic I/R injury can lead to the damage of hippocampus and cerebral cortex, and the increased serum exosomes induced by hepatic I/R plays an important role.

Focal Visual-Text Attention for Memex Question Answering.

Recent insights on language and vision with neural networks have been successfully applied to simple single-image visual question answering. However, to tackle real-life question answering problems on multimedia collections such as personal photo albums, we have to look at whole collections with sequences of photos. This paper proposes a new multimodal MemexQA task: given a sequence of photos from a user, the goal is to automatically answer questions that help users recover their memory about an event captured in these photos. In addition to a text answer, a few grounding photos are also given to justify the answer. The grounding photos are necessary as they help users quickly verifying the answer. Towards solving the task, we 1) present the MemexQA dataset, the first publicly available multimodal question answering dataset consisting of real personal photo albums; 2) propose an end-to-end trainable network that makes use of a hierarchical process to dynamically determine what media and what time to focus on in the sequential data to answer the question. Experimental results on the MemexQA dataset demonstrate that our model outperforms strong baselines and yields the most relevant grounding photos on this challenging task.

Theoretical analysis and design of hydro-hammer with a jet actuator: An engineering application to improve the penetration rate of directional well drilling in hard rock formations.

Rapid horizontal directional well drilling in hard or fractured formations requires efficient drilling technology. The penetration rate of conventional hard rock drilling technology in horizontal directional well excavations is relatively low, resulting in multiple overgrinding of drill cuttings in bottom boreholes. Conventional drilling techniques with reamer or diamond drill bit face difficulties due to the long construction periods, low penetration rates, and high engineering costs in the directional well drilling of hard rock. To improve the impact energy and penetration rate of directional well drilling in hard formations, a new drilling system with a percussive and rotary drilling technology has been proposed, and a hydro-hammer with a jet actuator has also been theoretically designed on the basis of the impulse hydro-turbine pressure model. In addition, the performance parameters of the hydro-hammer with a jet actuator have been numerically and experimentally analyzed, and the influence of impact stroke and pumped flow rate on the motion velocity and impact energy of the hydro-hammer has been obtained. Moreover, the designed hydro-hammer with a jet actuator has been applied to hard rock drilling in a trenchless drilling program. The motion velocity of the hydro-hammer ranges from 1.2 m/s to 3.19 m/s with diverse flow rates and impact strokes, and the motion frequency ranges from 10 Hz to 22 Hz. Moreover, the maximum impact energy of the hydro-hammer is 407 J, and the pumped flow rate is 2.3 m3/min. Thus, the average penetration rate of the optimized hydro-hammer improves by over 30% compared to conventional directional drilling in hard rock formations.

Two birds, one stone: dual targeting of the cancer cell surface and subcellular mitochondria by the galectin-3-binding peptide G3-C12.

Active tumor-targeting approaches using specific ligands have drawn considerable attention over the years. However, a single ligand often fails to simultaneously target the cancer cell surface and subcellular organelles, which limits the maximum therapeutic efficacy of delivered drugs. We describe a polymeric delivery system modified with the G3-C12 peptide for sequential dual targeting. In this study, galectin-3-targeted G3-C12 peptide was conjugated onto the N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer for the delivery of D(KLAKLAK)2 (KLA) peptide. G3-C12-HPMA-KLA exhibited increased receptor-mediated internalization into galectin-3-overexpressing PC-3 cells. Furthermore, G3-C12 peptide also directed HPMA-KLA conjugates to mitochondria. This occurred because the apoptosis signal triggered the accumulation of galectin-3 in mitochondria, and the G3-C12 peptide that specifically bound to galectin-3 was trafficked along with its receptor intracellularly. As a result, G3-C12-HPMA-KLA disrupted the mitochondrial membrane, increased the generation of reactive oxygen species (ROS) and induced cytochrome c release, which ultimately resulted in enhanced cytotoxicity. An in vivo study revealed that the G3-C12 peptide significantly enhanced the tumor accumulation of the KLA conjugate. In addition, G3-C12-HPMA-KLA exhibited the best therapeutic efficacy and greatly improved the animal survival rate. Our work demonstrates that G3-C12 is a promising ligand with dual-targeting functionality.

Infection with equine infectious anemia virus vaccine strain EIAVDLV121 causes no visible histopathological lesions in target organs in association with restricted viral replication and unique cytokine response.

The live equine infectious anemia virus (EIAV) vaccine strain EIAVDLV121 was developed by in vitro attenuation of a virulent strain, EIAVLN40, in the 1970s, and it has been demonstrated to induce protective immunity under laboratory and natural EIAV infection conditions. The detailed biological features of this attenuated virus remain to be further investigated. Experimental inoculation with EIAVDLV121 did not result in clinical symptoms even with immunosuppressive treatment in our previous studies. Here, we further investigated whether the replication of the vaccine strain EIAVDLV121 in experimentally infected horses causes histopathological lesions to develop in the targeted organs. Both the lungs and the spleen have been demonstrated to support EIAV replication. By evaluating the gross macroscopic and histological changes, we found that EIAVDLV121 did not cause detectable histopathological lesions and that it replicated several hundred times more slowly than its parental virulent strain, EIAVLN40, in tissues. Immunochemical assays of these tissues indicated that the primary target cells of EIAVDLV121 were monocytes/macrophages, but that EIAVLN40 also infected alveolar epithelial cells and vascular endothelial cells. In addition, both of these viral strains promoted the up- and down-regulation of the expression of various cytokines and chemokines, implicating the potential involvement of these cellular factors in the pathological outcomes of EIAV infection and host immune responses. Taken together, these results demonstrate that the EIAV vaccine strain does not cause obvious histopathological lesions or clinical symptoms and that it induces a unique cytokine response profile. These features are considered essential for EIAVDLV121 to function as an effective live vaccine.

Effects of insulin-like growth factor binding protein 4 on morphology and function of chick extraocular muscle / 中华实验眼科杂志

Background Researches have showed that the extraocular muscle injection of insulin-like growth factor(IGF) results in the thickness of extraocular muscle and enhancement of contractility,and lack of IGF probably is associated with pathogenesis of strabismus.If extraocular muscle injection of insulin-like growth factor binding protein 4(IGFBP-4),an inhibitor of IGF,can further ensure the effect of IGF is still under-investigation.Objective The aim of this study was to evaluate the effects of IGFBP-4 on the developing extraocular muscle.Methods IGFBP-4 of 2 μl(1 g/L)was injected into superior rectus muscles via supraorbital margin in the left eyes of 24 postnatal l-day-old chickens once every other day for five times,and the equivalent amount of normal saline solution was used in the same way in the fellow eyes as controls.The animals were sacrificed by overdose of anesthesia 2 days after the final injection and 12 animals were randomly selected for the maximal contractility test of superior rectus muscle.The other 12 pieces of superior rectus muscle of the chickens were obtained for the hematoxylin & eosin staining to evaluate the morphology of superior rectus muscle and calculate the myofiber diameter using imaging system.Results The maximal contractility was (1.602 ± 0.080) mN and(1.815±0.O10)mN in the IGFBP-4 injection group and normal saline solution group respectivily,showing a significant difference between the two groups(t =13.65,P＜0.01).The maximal contraction force in cross-sectional area was (95.500 ± 7.420) mN/cm2 in the IGFBP-4 injection group and it was significantly lower than that of the normal saline solution group(101.510±5.220)mN/cm2(t =28.81,P＜0.01).Histological examination showed that thin myofibers were obvious more in the IGFBP-4 injection group than those with saline injection.The mean diameter was (8.7 ± 0.5) μm in the IGFBP-4 injected group,and that of the normal saline group was(9.1 ±0.4) μm,there was no significant difference between them (t =0.75,P =0.46).However,significant differences were found in the number of different diameters of myofibers between the two groups(all at P＜0.05).Conclusions IGF is one of the key nutrition factors in the development of extraocular musele.The extraocular muscle injection of IGFBP-4 may cause the dysfunction and morphologic abnormality of extraocular muscle.

[The exploration and practice of Genetic Engineering teaching].

Genetic Engineering is an important specialized basic course for the students majoring in life sciences. The quality of teaching is directly related to the students' professional quality and innovation ability. In order to improve the teaching quatity and train advanced biotechnical students, we made some reforms to the contents and teaching methods of Genetic Engineering according to the experience accumulated in recent years.

Cerebral lymphatic blockage aggravates apoptosis of cortical neurons after subarachnoid hemorrhage in rats in vivo / 生理学报

This present study was performed to investigate the influence of cerebral lymphatic blockage (CLB) on apoptosis of cortical neurons after subarachnoid hemorrhage (SAH) in rats in vivo. Healthy adult Wistar rats were randomly divided into normal control group, SAH group and SAH+CLB group. SAH model was made by double injection of autologous blood into the cisterna magna. On the third day after the second cisternal injection, morphological changes of cortical cells were observed by hematoxylin-eosin (HE) combined with propidium iodide (PI) staining. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method was applied to determine in situ apoptosis in the cerebral cortex. Immunohistochemistry was conducted to detect the expression of Caspase-3 and Bcl-2 in cortical neurons. HE and PI staining showed that cortical neurons of SAH rats were partly shrinkable; the nuclei showed wavy, folded or wrinkled appearance, and some nuclei had the shape of crescent. The cortical neurons in SAH+CLB group distributed sparsely and the nuclear fragmentation, apoptotic bodies were found, surrounded by the formation of vacuoles. The numbers of TUNEL-positive cells in SAH group and SAH+CLB group were higher than that in the normal control group, while the number in SAH+CLB group was significantly higher than that in the SAH group. Caspase-3 expressions in SAH group and SAH+CLB group were higher than that in the normal control group, while the expression in SAH+CLB group was significantly higher than that in the SAH group. Bcl-2 expressions in SAH group and SAH+CLB group were higher than that in the normal control group, while the expression in the SAH+CLB group was significantly lower than that in SAH group. The results obtained suggest that CLB exacerbates the apoptosis of cortical neurons in rats after SAH by up-regulating Caspase-3 expression and down-regulating Bcl-2 expression.

Comparison of viremia formation between guinea-pigs infected with wild and attenuated (SA14-14-2) Japanese encephalitis viruses / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To study the viremia formation in guinea-pigs infected with wild type and attenuated Japanese encephalitis virus (JEV).</p><p><b>METHODS</b>Guniea pigs were inoculated intraperitoneally with different wild JEV strains and the attenuated vaccine strain and its parent virulent strain. Viremia was detected on different days following virus inoculation.</p><p><b>RESULTS</b>All the guinea-pigs inoculated with the wild JEV strains induced different levels of viremia (1.00-3.40 Lg pfu) on the 1st and 3rd day post inoculation. Using a virus titer of 10(4) pfu for inoculation, the animals inoculated with the SA14 parent strain induced relatively high viremia (10(2.4)-10(3.4) pfu), however no viremia coulds be detected on any tested days.</p><p><b>CONCLUSION</b>The degree of viremia in guinea pigs can be used as a new method to evaluate the attenuation of JEV.</p>

Studies on the biological and genetic characteristics of a highly neurovirulent Japanese encephalitis virus strain SA4 / 病毒学报

The biological and genetic characteristics of a highly neurovirulent JE virus strain SA4 were studied. Mice were inoculated intracerebrally with strain SA4 and SA14, and observed for 14 days, respectively. On different days, mice brains were harvested for titrations of the virus content in the brains. Full-length genome of SA4 was sequenced and compared with SA14 as well as other JE virus strains in the world. The results indicated that the mice inoculated by SA4 induced sickness and death more rapidly (24 hours faster) than those induced by the SA14. The virus titers in the brains of mice infected with SA4 were 0.5-1.0 lg PFU/mL higher than that infected with SA14. The sequence comparison indicated that the nucleotide and amino acid homology between SA4 and the other 21 JE strains were 84.6%-99.0% and 95.2%-99.7% respectively. Comparison with strain SA14 revealed that there were 17 amino acid differences between the two strains, of which 5 were in the E protein region. The results demonstrate that strain SA4 is a highly neurovirulent strain. The substitutions of the 17 amino acids in the SA4 strain can be the molecular basis for the biological characteristics of high neurovirulence.

[Application of atomic force microscopy in chromosome research].

Atomic force microscopy (AFM) is an effective apparatus for examination of the surface structure of specimens with a higher resolution. It can be used for real-time observation in vacuum, air, and liquid conditions. This review presented the basic principle of AFM and its significant advantages in biological sample research relative to other types of microscopes and summarized its application in chromosome research.

Cerebral lymphatic blockage aggravates apoptosis of hippocampal neurons induced by cerebrospinal fluid from experimental subarachnoid hemorrhage / 生理学报

This work was performed to determine the role of cerebral lymphatic drainage pathway in the development of neural injury following subarachnoid hemorrhage (SAH). SAH and cerebral lymphatic blockage (CLB) models in adult New Zealand rabbits were used. Cerebrospinal fluid (CSF) was obtained from experimental animals 5 d after modeling and was added into cultured rat hippocampal neurons. The neurons were randomly divided into blank control, normal CSF, SAH, and SAH+CLB groups. At different points of time, lactate dehydrogenase (LDH) leakage was detected by colorimetric method. Flow cytometry was used to detect the apoptosis of neurons. Expressions of Bax and heat-shock protein 70 (Hsp70) were determined by immunohistochemical staining. LDH leakage detection revealed that, compared with blank control group, CSF from normal rabbit did not damage the neurons, whereas the leakage of LDH increased in SAH group and SAH+CLB group. The increasing effect was more obvious in SAH+CLB group than that in SAH group. Normal CSF did not induce the apoptosis of neurons, whereas neuron apoptosis was found in SAH group and the apoptosis was even more severe in SAH+CLB group. Bax and Hsp70 protein expressions were found in both SAH and SAH+CLB groups. Expression of Bax protein in SAH+CLB group was stronger than that in SAH group in a time-dependent manner. At 0.5 h and 1 h, the expression of Hsp70 protein in SAH+CLB group was stronger than that in SAH group, whereas the expression became weaker at 2 h and 4 h. These results suggest that blockage of cerebral lymphatic drainage pathway deteriorates the damage of neurons treated with CSF from SAH, indicating this pathway may act as an endogenous protective role in SAH.

Study on the phenotypic characteristics of Japanese encephalitis virus strains isolated from different years / 病毒学报

In order to reveal the phenotypic characteristics of 17 JE virus strains isolated from different years, plaque sizes, mice neurovirulence and mice neuroinvasiveness of the isolates were studied and compared. BHK21 cell monolayers were used for testing the plaque sizes. The virus neurovirulence was tested in 9-11g mice inoculated intracerebrally and the virus neuroinvasiveness was tested in 9-11g and 14-16g by subcutaneous inoculation. Results showed that all the viruses produced clear plaques on the BHK21 cell monolayers with different sizes and all the virus strains appeared high neurovirulence in the mice with higher than lg8. 0/0.03 mL virus titers, while no apparent difference among them. The neuroinvasiveness (subcutaneous virulence) tested in the 9-11g mice had shown a little difference, but when tested in the 12-14 g mice,the difference was apparent. The results demonstrated that JEV in nature were highly neurovirulent with no apparent difference. However the neuroinvasiveness of the JEV in nature was greatly different, which didn't relate to the years of isolation and genotypes, but most of the viruses isolated from patients showed higher neuroinvasiveness.

[Comparative analysis of rDNA distribution in metaphase chromosomes of Cucurbitaceae species].

Fluorescence in situ hybridization (FISH) and double FISH experiments were carried out to ascertain the chromosomal distribution patterns of the 45S and 5S ribosomal DNAs in the three species of Cucurbitaceae. Five pairs of 45S rDNA loci and two pairs of 5S rDNA signals were detected on chromosomes of Cucurbita moschata Duch. Luffa cylindrical Roem. contained five pairs of 45S rDNA loci and one pair of 5S rDNA loci. In Benincasa hispida Cogn., two pairs of 45S rDNA sites and one pair of 5S rDNA site were detected. In this species, 5S rDNA and one pair of the 45S loci were collocated closely in chromosome 7S. 45S rDNA chromosomal distribution patterns were highly conserved among the three species, althoufh their number varied markedly. The 5S rDNA sites on chromosomes among the three species were highly polymorphic. We further discussed differentially evolutionary processes of 45S and 5S rDNA in plant genomes.

Construction and application of subgenomic replicon vectors of Japanese encephalitis virus / 病毒学报

Based on the infectious clone of JEV vaccine SA14-14-2, the subgenomic replicons pCTCJEV, pCTMJEV with large deletions in the structural region were constructed. Then they were transfected into BHK-21 cell, the RNA replication of JEV subgenome can be monitored by RT-PCR and the non-structural protein can be found expressed in the cell by IFA. To explore the possibility of using a reporter gene assay to monitor synthesis of the positive-strand and the negative-strand JEV RNA, we inserted an enhanced green fluorescence protein (EGFP) gene into the 3'-UTR of pCTCJEV, pCTMJEV under the control of the internal ribosomal entry site (IRES) of encephalomyelocarditis virus RNA. After transfection, the EGFP fluorescence could be seen under the fluorescence microscope 1 day later,and maintained for more than a week with no apparent cytopathic effect. The constructed JEV replicons would provide valuable tools to provide a possible vector for a long-lasting RNA virus expression system.

[Cytogenetic maps and their applications in plants].

Integrated cytogenetic maps encompass the information from both genetic maps and cytological maps. It is possible for cytogenetic maps to simultaneously report the cytological and genetic position of a maker. To constructure cytogenetic maps it is necessary to relate the markers mapped across linkage groups to cytological position on chromosomes. Cytogenetic maps have been constructured primarily in two ways. The first general strategy is to utilize the chromosome breakpoints to determine the location of genetically mapped markers on the chromosomes. A second way is by the direct hybridization of genetically mapped sequences onto chromosomes by FISH. In addition, a novel approach is to use RN-cM maps to predict the physical position of genetic markers on the chromosomes. Cytogenetic maps suggest that both the density of genes and the frequency of recombination increase towards the distal regions of chromosome arms, and they play significant roles in revealing gene colinearity between two species, exploring the evolution relationship between both of them and in map-based gene isolation.