Biodistributions of radioactive bipositive metal ions in tumor-bearing animals

Distributions of the nuclides ⁶⁵ZnCl₂, ⁸⁵SrCl₂, ⁵⁸CoCl₂ and ¹⁰³PdCl₂ in tumor-bearing animals were determined, and, in addition, the distributions of these nuclides in tumor tissues were observed. Their subcellular distribution in tumor and liver was also examined. Generally speaking, retention values of these bipositive metal ions in tumor were smaller than those of tri-, quadri- and pentavalent metal ions. In the case of ⁸⁵SrCl₂, a large amount of this nuclide was taken up by the bone and remained there for a long time. In the case of ¹⁰³PdCl₂, ^l03Pd was avidly taken up by the kidney and liver. Very little of the ¹⁰³Pd taken up into the kidney and liver was excreted. ⁶⁵Zn and ¹⁰³Pd were concentrated in the viable tumor tissue and were not seen in necrotic tumor tissue. In the case of ⁵⁸Co, lysosome played an important role in liver accumulation and played a minor role in tumor accumulation. The distribution of ⁵⁸Co in tumor and liver was fairly similar to that of ⁶⁷Ga, ¹¹¹In, ¹⁶⁹Yb, ⁴⁶Sc, ⁵¹Cr, ⁹⁵Zr, ¹⁸¹Hf, ⁹⁵Nb and ¹⁸²Ta which were reported previously. Lysosome did not play an important role in the accumulation of ⁶⁵Zn, ⁸⁵Sr and ¹⁰³Pd into tumor and liver.     

用不同模型估计绒山羊早期生长性状遗传参数的比较

利用内蒙古伊盟阿尔巴斯白绒山羊种羊场从1993年至2000年间白绒山羊的早期生长性状(包括出生重、断乳重、日增重和周岁重)的场内测定数据,对4种不同动物模型估计遗传参数的差异进行了比较分析。不同模型中对母体遗传效应和母体环境效应作了不同的考虑：模型I,不考虑母体遗传效应和母体环境效应;模型Ⅱ,仅考虑母体遗传效应;模型Ⅲ,仅考虑母体环境效应;模型Ⅳ,同时考虑母体遗传效应和母体环境效应。利用MTD-FREML程序采用非求导约束最大似然法(DFREML)估计各模型中的方差组分,用似然比检验对不同模型的差异进行检验。结果表明：对于出生重,母体遗传效应和母体环境效应都有极显著的影响,应采用模型Ⅳ进行分析;对于断乳重和日增重,母体遗传效应的影响不显著,而母体环境效应的影响极显著,应采用模型Ⅲ进行分析;对于周岁重,母体环境效应的影响不显著,而母体遗传效应的影响显著,应采用模型Ⅱ进行分析。     

Bilateral Common Carotid Artery Occlusion as an Adequate Preconditioning Stimulus to Induce Early Ischemic Tolerance to Focal Cerebral Ischemia

There is accumulating evidence, that ischemic preconditioning - a non-damaging ischemic challenge to the brain - confers a transient protection to a subsequent damaging ischemic insult. We have established bilateral common carotid artery occlusion as a preconditioning stimulus to induce early ischemic tolerance to transient focal cerebral ischemia in C57Bl6/J mice. In this video, we will demonstrate the methodology used for this study.     

Isolation of Sensory Neurons of Aplysia californica for Patch Clamp Recordings of Glutamatergic Currents

The marine gastropod mollusk Aplysia californica has a venerable history as a model of nervous system function, with particular significance in studies of learning and memory. The typical preparations for such studies are ones in which the sensory and motoneurons are left intact in a minimally dissected animal, or a technically elaborate neuronal co-culture of individual sensory and motoneurons. Less common is the isolated neuronal preparation in which small clusters of nominally homogeneous neurons are dissociated into single cells in short term culture. Such isolated cells are useful for the biophysical characterization of ion currents using patch clamp techniques, and targeted modulation of these conductances. A protocol for preparing such cultures is described. The protocol takes advantage of the easily identifiable glutamatergic sensory neurons of the pleural and buccal ganglia, and describes their dissociation and minimal maintenance in culture for several days without serum.     

Using RNA-mediated Interference Feeding Strategy to Screen for Genes Involved in Body Size Regulation in the Nematode C. elegans

Double-strand RNA-mediated interference (RNAi) is an effective strategy to knock down target gene expression^1-3. It has been applied to many model systems including plants, invertebrates and vertebrates. There are various methods to achieve RNAi in vivo^4,5. For example, the target gene may be transformed into an RNAi vector, and then either permanently or transiently transformed into cell lines or primary cells to achieve gene knockdown effects; alternatively synthesized double-strand oligonucleotides from specific target genes (RNAi oligos) may be transiently transformed into cell lines or primary cells to silence target genes; or synthesized double-strand RNA molecules may be microinjected into an organism. Since the nematode C. elegans uses bacteria as a food source, feeding the animals with bacteria expressing double-strand RNA against target genes provides a viable strategy⁶. Here we present an RNAi feeding method to score body size phenotype. Body size in C. elegans is regulated primarily by the TGF- β - like ligand DBL-1, so this assay is appropriate for identification of TGF-β signaling components⁷. We used different strains including two RNAi hypersensitive strains to repeat the RNAi feeding experiments. Our results showed that rrf-3 strain gave us the best expected RNAi phenotype. The method is easy to perform, reproducible, and easily quantified. Furthermore, our protocol minimizes the use of specialized equipment, so it is suitable for smaller laboratories or those at predominantly undergraduate institutions.     

Individual and synergistic effects of male external genital traits in sexual selection

Male genital traits exhibit extraordinary interspecific phenotypic variation. This remarkable and general evolutionary trend is widely considered to be the result of sexual selection. However, we still do not have a good understanding of whether or how individual genital traits function in different competitive arenas (episodes of sexual selection), or how different genital traits may interact to influence competitive outcomes. Here, we use an experimental approach based on high‐precision laser phenotypic engineering to address these outstanding questions, focusing on three distinct sets of micron‐scale external (nonintromittent) genital spines in male Drosophila kikkawai Burla (Diptera: Drosophilidae). Elimination of the large pair of spines on the male secondary claspers sharply reduced male ability to copulate, yet elimination of the other sets of spines on the primary and secondary claspers had no significant effects on copulation probability. Intriguingly, both the large spines on the secondary claspers and the cluster of spines on the primary claspers were found to independently promote male competitive fertilization success. Moreover, when large and small secondary clasper spines were simultaneously shortened in individual males, these males suffered greater reductions in fertilization success relative to males whose traits were altered individually, providing evidence for synergistic effects of external genital traits on fertilization success. Overall, the results are significant in demonstrating that a given genital trait (the large spines on the secondary claspers) can function in different episodes of sexual selection, and distinct genital traits may interact in sexual selection. The results offer an important contribution to evolutionary biology by demonstrating an understudied selective mechanism, operating via subtle trait interactions in a post‐insemination context, by which genital traits may be co‐evolving.     

Intravital Microscopy for Imaging Subcellular Structures in Live Mice Expressing Fluorescent Proteins

Here we describe a procedure to image subcellular structures in live rodents that is based on the use of confocal intravital microscopy. As a model organ, we use the salivary glands of live mice since they provide several advantages. First, they can be easily exposed to enable access to the optics, and stabilized to facilitate the reduction of the motion artifacts due to heartbeat and respiration. This significantly facilitates imaging and tracking small subcellular structures. Second, most of the cell populations of the salivary glands are accessible from the surface of the organ. This permits the use of confocal microscopy that has a higher spatial resolution than other techniques that have been used for in vivo imaging, such as two-photon microscopy. Finally, salivary glands can be easily manipulated pharmacologically and genetically, thus providing a robust system to investigate biological processes at a molecular level.In this study we focus on a protocol designed to follow the kinetics of the exocytosis of secretory granules in acinar cells and the dynamics of the apical plasma membrane where the secretory granules fuse upon stimulation of the beta-adrenergic receptors. Specifically, we used a transgenic mouse that co-expresses cytosolic GFP and a membrane-targeted peptide fused with the fluorescent protein tandem-Tomato. However, the procedures that we used to stabilize and image the salivary glands can be extended to other mouse models and coupled to other approaches to label in vivo cellular components, enabling the visualization of various subcellular structures, such as endosomes, lysosomes, mitochondria, and the actin cytoskeleton.     

Direct Intraventricular Delivery of Drugs to the Rodent Central Nervous System

Due to an inability to cross the blood brain barrier, certain drugs need to be directly delivered into the central nervous system (CNS). Our lab focuses specifically on antisense oligonucleotides (ASOs), though the techniques shown in the video here can also be used to deliver a plethora of other drugs to the CNS. Antisense oligonucleotides (ASOs) have the capability to knockdown sequence-specific targets ¹ as well as shift isoform ratios of specific genes ². To achieve widespread gene knockdown or splicing in the CNS of mice, the ASOs can be delivered into the brain using two separate routes of administration, both of which we demonstrate in the video.The first uses Alzet osmotic pumps, connected to a catheter that is surgically implanted into the lateral ventricle. This allows the ASOs to be continuously infused into the CNS for a designated period of time. The second involves a single bolus injection of a high concentration of ASO into the right lateral ventricle. Both methods use the mouse cerebral ventricular system to deliver the ASO to the entire brain and spinal cord, though depending on the needs of the study, one method may be preferred over the other.