[Deubiquitinating enzyme MINDY1 is an independent risk factor for the maintenance of stemness and poor prognosis in liver cancer cells].

Objective: To explore the key deubiquitinating enzymes that maintain the stemness of liver cancer stem cells and provide new ideas for targeted liver cancer therapy. Methods: The high-throughput CRISPR screening technology was used to screen the deubiquitinating enzymes that maintain the stemness of liver cancer stem cells. RT-qPCR and Western blot were used to analyze gene expression levels. Stemness of liver cancer cells was detected by spheroid-formation and soft agar colony formation assays. Tumor growth in nude mice was detected by subcutaneous tumor-bearing experiments. Bioinformatics and clinical samples were examined for the clinical significance of target genes. Results: MINDY1 was highly expressed in liver cancer stem cells. The expression of stem markers, the self-renewal ability of cells, and the growth of transplanted tumors were significantly reduced and inhibited after knocking out MINDY1, and its mechanism of action may be related to the regulation of the Wnt signaling pathway. The expression level of MINDY1 was higher in liver cancer tissues than that in adjacent tumors, which was closely related to tumor progression, and its high expression was an independent risk factor for a poor prognosis of liver cancer. Conclusion: The deubiquitinating enzyme MINDY1 promotes stemness in liver cancer cells and is one of the independent predictors of poor prognosis in liver cancer.

Genome-wide association analysis of eggshell color of an F2 generation population reveals candidate genes in chickens.

Eggshell color is an important visual characteristic that affects consumer preferences for eggs. Eggshell color, which has moderate to high heritability, can be effectively enhanced through molecular marker selection. Various studies have been conducted on eggshell color at specific time points. However, few longitudinal data are available on eggshell color. Therefore, the objective of this study was to investigate eggshell color using the Commission International de L'Eclairage L*a*b* system with multiple measurements at different ages (age at the first egg and at 32, 36, 40, 44, 48, 52, 56, 60, 66, and 72 weeks) within the same individuals from an F2 resource population produced by crossing White Leghorn and Dongxiang Blue chicken. Using an Affymetrix 600 single nucleotide polymorphism (SNP) array, we estimated the genetic parameters of the eggshell color trait, performed genome-wide association studies (GWASs), and screened for the potential candidate genes. The results showed that pink-shelled eggs displayed a significant negative correlation between L* values and both a* and b* values. Genetic heritability based on SNPs showed that the heritability of L*, a*, and b* values ranged from 0.32 to 0.82 for pink-shelled eggs, indicating a moderate to high level of genetic control. The genetic correlations at each time point were mostly above 0.5. The major-effect regions affecting the pink eggshell color were identified in the 10.3-13.0 Mb interval on Gallus gallus chromosome 20, and candidate genes were selected, including SLC35C2, PCIF1, and SLC12A5. Minor effect polygenic regions were identified on chromosomes 1, 6, 9, 12, and 15, revealing 11 candidate genes, including MTMR3 and SLC35E4. Members of the solute carrier family play an important role in influencing eggshell color. Overall, our findings provide valuable insights into the phenotypic and genetic aspects underlying the variation in eggshell color. Using GWAS analysis, we identified multiple quantitative trait loci (QTLs) for pink eggshell color, including a major QTL on chromosome 20. Genetic variants associated with eggshell color may be used in genomic breeding programs.

Loss-of-function mutations in the EGF-CFC gene CFC1 are associated with human left-right laterality defects.

All vertebrates display a characteristic asymmetry of internal organs with the cardiac apex, stomach and spleen towards the left, and the liver and gall bladder on the right. Left-right (L-R) axis abnormalities or laterality defects are common in humans (1 in 8,500 live births). Several genes (such as Nodal, Ebaf and Pitx2) have been implicated in L-R organ positioning in model organisms. In humans, relatively few genes have been associated with a small percentage of human situs defects. These include ZIC3 (ref. 5), LEFTB (formerly LEFTY2; ref. 6) and ACVR2B (encoding activin receptor IIB; ref. 7). The EGF-CFC genes, mouse Cfc1 (encoding the Cryptic protein; ref. 9) and zebrafish one-eyed pinhead (oep; refs 10, 11) are essential for the establishment of the L-R axis. EGF-CFC proteins act as co-factors for Nodal-related signals, which have also been implicated in L-R axis development. Here we identify loss-of-function mutations in human CFC1 (encoding the CRYPTIC protein) in patients with heterotaxic phenotypes (randomized organ positioning). The mutant proteins have aberrant cellular localization in transfected cells and are functionally defective in a zebrafish oep-mutant rescue assay. Our findings indicate that the essential role of EGF-CFC genes and Nodal signalling in left-right axis formation is conserved from fish to humans. Moreover, our results support a role for environmental and/or genetic modifiers in determining the ultimate phenotype in humans.

Compensating for gyroradius effects in beamlines with small Helmholtz coils.

Measurements of lighter, low-energy charged particles in a laboratory beamline are complicated due to the influence of Earth's magnetic field. Rather than nulling out the Earth's magnetic field over the entire facility, we present a new way to correct particle trajectories using much more spatially limited Helmholtz coils. This approach is versatile and easy to incorporate in a wide range of facilities, including the existing ones, enabling measurements of low-energy charged particles in a laboratory beamline.

Genome-wide association studies for mottled eggs in chickens using a high-density single-nucleotide polymorphism array.

Mottled eggs in layer chickens are gaining increasing attention because of the economic impact on the egg industry caused by the reduced sale value of commodity eggs. However, the genetic architecture underlying mottled eggs is not well understood. The genetic architecture underlying the mottled egg trait was investigated using genome-wide association studies (GWAS) by high-density arrays, using a total of 407 pink eggs and 799 blue eggs from an F2 resource population generated by crossing Dongxiang Blue-shelled and White Leghorn chickens. The mottled egg score in blue eggs was found to be higher than that in pink eggs. The single-nucleotide polymorphism heritability of mottled egg at laying day and storage for 7 days was 0.18 and 0.20, respectively. Bivariate GWAS provided 29 significant loci, mainly located on GGA2, GGA3, GGA8, GGA10, GGA15, GGA17, and GGA23, affecting mottled egg on laying day. Candidate genes RIMS2, SLC25A32, RIMBP2, VPS13B, and RGS3 were obtained for mottled eggshell by bivariate GWAS and gene annotation. Our findings provide new insights into the genetic architecture of mottled egg in hens, and demonstrate that a genomic selection method would be profitable for breeding out the mottled egg trait.

Effects of energy-restricted feeding during rearing on sexual maturation and reproductive performance of Rugao layer breeders.

The aim of this study was to assess the effects of energy-restricted feeding during rearing on the sexual maturation and reproductive performance of Rugao layer breeders. A total of 2,400 8-wk-old Rugao layer breeders were randomly assigned to one of 5 groups (480 pullets per group) with eight replicates and were fed one of 5 diets that were nutritionally similar with the exception of apparent metabolizable energy corrected for nitrogen (AMEn) content (2,850, 2,750, 2,650, 2,550, and 2,450 kcal AMEn/kg) from 8 to 18 wks of age. The daily amount of feed was restricted to the absolute quantity of the diet consumed by laying hens fed 2,850 kcal AMEn per kg diet ad libitum (control). From 18 to 52 wks of age, all hens were fed basal diets ad libitum. The body weight of layer breeders at 18 wks of age decreased linearly with increasing energy restriction (P < 0.001), but caught up within 3 wks of ad libitum feeding (P = 0.290). The coefficient of variation of the body weight of the hens at 18, 21, and 24 wks of age decreased linearly (P = 0.010, 0.025, and 0.041, respectively) with increasing energy restriction during rearing. Energy-restricted feeding delayed sexual organ development at 18, 20, and 22 wks of age, including the number of large yellow follicles, oviduct length, oviduct length index, oviduct index, and ovary stroma index (P < 0.05), and delayed sexual maturity, including the age at laying the first egg and the age at 5% and 50% egg production (P = 0.042, 0.004, and 0.029, respectively). Consequently, egg number from 5% to 50% egg production decreased linearly as the degree of energy restriction increased (P = 0.001) and egg production of hens in the energy-restricted feeding groups was lower than that of hens in the ad libitum feeding group (6.36, 6.43, 6.4, and 4.61% vs. 14.29%; P < 0.05) from 18 to 20 wks of age. Furthermore, egg weight increased linearly as energy restriction increased (P < 0.001) and laying hens in the most severe energy-restricted feeding group had more setting eggs (normal eggs weighing >40 g) than hens in the ad libitum feeding and lighter energy-restricted feeding groups (149.57 vs. 144.34, 142.66, 143.63, and 141.78; P < 0.05). No significant differences were observed in fertility, hatchability of fertile eggs, and hatchability of setting eggs (P = 0.381, 0.790, and 0.605, respectively). In conclusion, moderate energy restriction (85.97%, 2,450 vs. 2,850 kcal AMEn/kg) from 8 to 18 wks of age increased egg weight as well as the production of setting eggs in native layer breeders throughout the laying period, without adverse effects on productive performance from 18 to 52 wks of age, or fertility and hatchability at 52 wks of age.

Effects of taurine on growth performance, antioxidant capacity, and lipid metabolism in broiler chickens.

To investigate the effects of dietary taurine supplementation on growth performance, antioxidant status, and lipid metabolism in broilers, 384 male broilers (Arbor Acres, 1 D of age) were randomly allocated into 4 groups with 8 replicates of 8 birds. Dietary treatments were supplemented with taurine at the level of 0.00, 2.50, 5.00, and 7.50 g/kg of the diet (denoted as CON, TAU1, TAU2, TAU3, respectively). The BW gain from 1 to 21 D and from 22 to 42 D were all increased linearly (linear, P < 0.001) by taurine supplementation. Throughout the trial period, the highest BW gain and favorable gain-to-feed ratio were observed in the TAU2 group. Taurine supplementation increased the antioxidant enzyme activities and decreased (linear, P < 0.001) the content of malondialdehyde in both serum and the liver of broilers and alleviated oxidative damage through enhancing (P < 0.05) the hepatic genes expression of nuclear factor erythroid-2-related factor 2 (NRF2), glutathione peroxidase (GPX), and heme oxygenase-1 (HO-1). Correspondingly, in serum, the activities of hepatic lipase and total lipase were decreased linearly and quadratically (linear and quadratic, P < 0.001) with the increasing inclusion of taurine in the diet. Meanwhile, in serum, the content of triglycerides was significantly decreased (P < 0.05), and except for TAU3, the total cholesterol content was also significantly decreased (P < 0.05) by taurine supplementation. In addition, the hepatic content of triglycerides was significantly decreased (P < 0.05) in the TAU1 and TAU2 groups. Compared with the CON group, the hepatic genes expression of adenosine monophosphate-activated protein kinase alpha (AMPKα), silent 1, (SIRT1) and carnitine palmitoyltransferase 1 (CPT-1) were all increased (P < 0.05), and sterol regulatory element-binding protein-1 (SREBP-1) expression was decreased (P < 0.05) in the TAU2 group. These results indicated that taurine supplementation improved the growth performance, antioxidant capacity, and lipid metabolism of broilers.

Effects of high-dose selenium-enriched yeast on laying performance, egg quality, clinical blood parameters, organ development, and selenium deposition in laying hens.

Organic selenium (Se) supplementation from Se-enriched yeast (SY) has been advocated and approved for use in animal feeds by some nutritionists and researchers rather than inorganic Se from sodium selenite. However, there is little available safety data of SY in laying hens. A subchronic study was conducted to determine if high-dose SY affects the safety of hens. A total of 768, 30-wk-old, Hy-Line Brown hens were randomly assigned to 1 of 4 groups (192 laying hens per group) with 6 replicates of 32 birds each. After a 2-wk acclimation period, the birds were fed diets supplemented with 0, 0.3, 1.5, or 3.0 mg/kg Se from SY for 12 wk. Throughout the study period, clinical observations and laying performance were measured. The hematological and chemical parameters of blood samples and the Se concentration in eggs were examined after SY supplementation for 4, 8, and 12 wk, and the egg quality was measured after 12 wk. At the end of the study, full post-mortem examinations were conducted: breast Se concentrations were measured, visceral, and reproductive organs were weighed, and specified tissues were collected for subsequent histological examinations. Although the Se concentrations in the eggs and breast meat from hens fed 3.0 mg/kg of Se from SY were 1036.73% and 2127.93% higher (P < 0.001) than those from hens fed a basal diet after 12 wk, no treatment-related changes of toxicological significance were observed. Therefore, up to 3 mg/kg organic Se from SY can be used to supplement the diets for laying hens without adverse effects following 84-d administration.

Effects of bamboo leaf extract on growth performance, meat quality, and meat oxidative stability in broiler chickens.

This study was conducted to investigate the effects of dietary bamboo leaf extract (BLE) on growth performance, meat quality, oxidative stability, and nuclear factor erythroid 2-related factor 2 (Nrf2) related gene expression of breast meat in broilers. A total of 576 one-day-old male Arbor Acres broilers were divided into 6 groups. The control group (CTR) was fed basal diet, while BLE1, BLE2, BLE3, BLE4, and BLE5 were fed basal diet supplemented with 1.0, 2.0, 3.0, 4.0, and 5.0 g BLE per kg feed, respectively. Compared with the CTR group, BLE2 and BLE5 increased average daily feed intake from 1 to 21 D and 22 to 42 D (P < 0.05), BLE1 and BLE2 improved average daily gain (ADG) and feed to gain ratio from 22 to 42 D (P < 0.05). Throughout the trial period, the highest body weight and favorable ADG and feed to gain ratio were observed in the BLE2 group. The drip loss at 24 h and pH at 45 min postmortem of breast meat were linearly improved by BLE supplementation (P < 0.05). Shear force was significantly lower in BLE2 and BLE3 than that in CTR group. Increasing supplementation of BLE linearly improved free radical scavenging capacity and decreased malondialdehyde content of breast meat during 12 D of storage (P < 0.05). Total antioxidant capacity and glutathione peroxidase activity were linearly increased by BLE supplementation (P < 0.05). Compared with the CTR group, the mRNA expression of Nrf2 and glutathione peroxidase in BLE3, BLE4, and BLE5 groups was significantly promoted, and glutathione S-transferase gene expression was increased in BLE2, BLE4, and BLE5 (P < 0.05). The highest (P < 0.05) heme oxygennase-1 gene expression was observed in BLE5. In conclusion, broiler supplemented with BLE improved growth performance and meat quality, BLE supplementation might activate Nrf2 pathway to alleviate lipid oxidation and increase antioxidant capacity of breast meat. The dosage of 2.0 to 3.0 g/kg BLE in broiler diet was recommanded.

Comparison of dynamic change of egg selenium deposition after feeding sodium selenite or selenium-enriched yeast.

The aim of this study was to compare the dynamic change of egg selenium (Se) deposition after sodium selenite (SS) or selenium-enriched yeast (SY) supplementation for 1, 3, 5, 7, 14, 21, 28, 56, and 84 d. A total of 576 32-wk-old Hy-Line Brown laying hens were randomly assigned to 3 groups (192 laying hens per group) with 6 replicates, and fed a basal diet (without Se supplementation) or basal diets with 0.3 mg/kg of Se from SS or 0.3 mg/kg of Se from SY, respectively. The results showed that the Se concentrations in the eggs from hens fed a SY-supplemented diet were significantly higher (P < 0.001) than those from hens fed a SS-supplemented diet or a basal diet after 3 d. And the Se concentrations in the eggs from hens fed a SS-supplemented diet were significantly higher (P < 0.001) than those from hens fed a basal diet after 14 d. There was a positive linear and quadratic correlation between Se concentrations in the eggs from hens fed a SY-supplemented diet (r2 = 0.782, P < 0.001; r2 = 0.837, P < 0.001) or SS-supplemented diet (r2 = 0.355, P < 0.001; r2 = 0.413, P < 0.001) and number of feeding days. The Se concentrations in the breasts from hens fed a SY-supplemented diet were 126.98% higher (P < 0.001) than those from hens fed a SS-supplemented diet, and were 299.44% higher (P < 0.001) than those from hens fed a basal diet after the 84-d feeding period. In conclusion, the dietary Se was gradually transferred into eggs with the extension of the experimental duration. The deposition rate of Se in the eggs from hens fed a SY-supplemented diet was much more rapid than that from hens fed a SS-supplemented diet, and the organic Se from SY had higher bioavailability as compared to inorganic Se from SS.

The EGF-CFC gene family in vertebrate development.

EGF-CFC genes encode extracellular proteins that play key roles in intercellular signaling pathways during vertebrate embryogenesis. Mutations in zebrafish and mouse EGF-CFC genes lead to defects in germ-layer formation, anterior-posterior axis orientation and left-right axis specification. In addition, members of the EGF-CFC family have been implicated in carcinogenesis. Although formerly regarded as signaling molecules that are distant relatives of epidermal growth factor (EGF), recent findings indicate that EGF-CFC proteins act as essential cofactors for Nodal, a member of the transforming growth factor beta (TGF-beta) family. Here, we review molecular genetic evidence from mouse and zebrafish on biological and biochemical roles of the EGF-CFC family, and discuss differing models for EGF-CFC protein function.

A novel PF/PN motif inhibits nuclear localization and DNA binding activity of the ESX1 homeoprotein.

Despite their significance for mammalian embryogenesis, the molecular mechanisms that regulate placental growth and development have not been well defined. The Esx1 homeobox gene is of particular interest because it is among the few regulatory genes that have specific expression and function in the placenta during murine development. In addition, the ESX1 protein contains several notable features that are not often associated with homeoproteins, including an atypical homeodomain of the paired-like class, a proline-rich region that contains an SH3 binding motif, and a novel repeat region consisting of prolines alternating with phenylalanines or asparagines that we term the PF/PN motif. We have found that the ESX1 protein is expressed in the labyrinth layer of the placenta in vivo, where its subcellular localization is primarily cytoplasmic. Our results suggest that this unexpected subcellular localization is conferred by the PF/PN motif, which inhibits nuclear localization of ESX1 in cell culture, as well as its DNA binding activity in vitro. Finally, we show that the proline-rich region of ESX1 mediates interactions in vitro with the c-abl SH3 domain as well as with certain WW domains. We propose that the PF/PN motif provides a novel mechanism for regulating nuclear entry and that the essential function of ESX1 during placental development is mediated by its ability to couple cytoplasmic signal transduction events with transcriptional regulation in the nucleus.

Heterodimerization of Msx and Dlx homeoproteins results in functional antagonism.

Protein-protein interactions are known to be essential for specifying the transcriptional activities of homeoproteins. Here we show that representative members of the Msx and Dlx homeoprotein families form homo- and heterodimeric complexes. We demonstrate that dimerization by Msx and Dlx proteins is mediated through their homeodomains and that the residues required for this interaction correspond to those necessary for DNA binding. Unlike most other known examples of homeoprotein interactions, association of Msx and Dlx proteins does not promote cooperative DNA binding; instead, dimerization and DNA binding are mutually exclusive activities. In particular, we show that Msx and Dlx proteins interact independently and noncooperatively with homeodomain DNA binding sites and that dimerization is specifically blocked by the presence of such DNA sites. We further demonstrate that the transcriptional properties of Msx and Dlx proteins display reciprocal inhibition. Specifically, Msx proteins act as transcriptional repressors and Dlx proteins act as activators, while in combination, Msx and Dlx proteins counteract each other's transcriptional activities. Finally, we show that the expression patterns of representative Msx and Dlx genes (Msx1, Msx2, Dlx2, and Dlx5) overlap in mouse embryogenesis during limb bud and craniofacial development, consistent with the potential for their protein products to interact in vivo. Based on these observations, we propose that functional antagonism through heterodimer formation provides a mechanism for regulating the transcriptional actions of Msx and Dlx homeoproteins in vivo.

Safety evaluation of daidzein in laying hens: Effects on laying performance, hatchability, egg quality, clinical blood parameters, and organ development.

Daidzein has become increasingly popular as a dietary supplement, particularly for postpeak-estrus animals, as a safe and natural alternative estrogen-like compound. However, there is little available safety data of daidzein in laying hens. A study was conducted to examine if high-dose daidzein affected the safety of hens, including mortality, laying performance, egg quality, hematological parameters, clinical chemical parameters, organ development parameters, and hatchability. A total of 2,448 42-wk-old Rugao laying hens were randomly assigned to 4 groups with 6 replicates of 102 birds each (612 laying hens per group). After a 2-wk acclimation period, the birds were fed diets supplemented with 0, 10, 100, or 200 mg/kg of daidzein for 12 wk. The hatchability of setting eggs increased linearly with increasing dietary daidzein supplementation (P = 0.034), while the hatchability of fertile eggs also tended to increase linearly (P = 0.069). The red cell distribution width (RCDW) and coefficient variation of RCDW showed an increasing and then decreasing quadratic response to increasing dietary daidzein supplementation (P = 0.001 and 0.002, respectively). No statistically significant changes were observed in mortality, laying performance, egg quality, clinical chemistry parameters, or organ development parameters (P > 0.05). The magnitude of these hematological changes was such that they were considered to be of no toxicological significance. Therefore, a nominal daidzein concentration of 200 mg/kg is not expected to cause adverse effects following daily administration to laying hens for 84 d.

Cell signaling in growth and development: the 11th Annual CABM Symposium, October 8-9, 1997.

While many topics were discussed during this symposium, several common themes emerged from the presentations. First, it is increasingly evident that regulation of ligand-receptor interactions is complex and can occur at nearly every conceivable step, including protein processing for release from or tethering to the cell surface, diffusibility through tissues, binding to soluble inhibitors, and competition with antagonists for receptor binding. In particular, the availability of these regulatory steps allows for a range of potential mechanisms by which ligand signaling can be modulated by other protein factors, such as in the case of fringe and its effects on signaling through the Notch receptor. Secondly, a major area of effort in the signaling field will increasingly focus on how cells integrate the signals received from different pathways to coordinate specific developmental responses. For example, as McMahon pointed out, the major signaling pathways that govern the anterior-posterior, dorsal-ventral, and proximal-distal axes of the developing limb bud have now been identified, yet it is completely unclear how these pathways interact to produce positional information in three dimensions. Thirdly, biochemical and structural investigations are now providing insights into the nature of the feedback mechanisms that regulate the strength and duration of activated signals, and how in some cases, these feedback loops can also provide a 'memory' of the signaling response, such as in the case of the adaptation found in bacterial chemotaxis. Finally, the structural analyses of signal transducing molecules remind us of the necessity to understand the mechanistic details of how active and inactive states are maintained, particularly since distant protein modifications can lead to global conformational changes that alter protein activity. These and other general insights underscore the value of broad-based meetings that cut across a range of disciplines and methodologies, such as this CABM symposium, and provide ideas for future directions of investigation.

Physical analysis of Tn10- and IS10-promoted transpositions and rearrangements.

We have investigated by Southern blot hybridization the rate of IS10 transposition and other Tn10/IS10-promoted rearrangements in Escherichia coli and Salmonella strains bearing single chromosomal insertions of Tn10 or a related Tn10 derivative. We present evidence for three primary conclusions. First, the rate of IS10 transposition is approximately 10(-4) per cell per bacterial generation when overnight cultures are grown and plated on minimal media and is at least ten times more frequent than any other Tn10/IS10-promoted DNA alteration. Second, all of the chromosomal rearrangements observed can be accounted for by two previously characterized Tn10-promoted rearrangements: deletion/inversions and deletions. Together these rearrangements occur at about 10% the rate of IS10 transposition. Third, the data suggest that intramolecular Tn10-promoted rearrangements preferentially use nearby target sites, while the target sites for IS10 transposition events are scattered randomly around the chromosome.

Comparison of MSX-1 and MSX-2 suggests a molecular basis for functional redundancy.

This study examines the biochemical properties of two members of the murine MSX family, MSX-1 and MSX-2, which have been implicated to have partially overlapping functions during embryogenesis. Our analyses show that MSX-1 and MSX-2 share many features in common including their DNA binding and transcriptional properties. In particular, MSX-1 and MSX-2 interact with a common consensus DNA site, and exhibit similar DNA binding site preferences. However, MSX-2 has a higher apparent affinity for DNA, and the distinction between MSX-1 and MSX-2 resides in their differing sequences N-terminal to the homeodomain. With respect to their transcriptional properties, both MSX-1 and MSX-2 function as repressors and share the distinct property that they do so independently of their consensus DNA binding sites. However, MSX-1 is a more potent repressor, and the difference between these proteins also maps to their N-terminal regions. Similarly, the expression patterns of Msx-1 and Msx-2 as examined by whole mount in situ hybridization are related but not identical. Thus, Msx-1 and Msx-2 are co-expressed in the limbs, neural tube, and branchial arches; however, Msx-1 has a broader expression pattern overall and is expressed uniquely in certain embryonic regions. These features suggest that these members of the Msx family are 'equivalent but not equal' and that their proposed redundancy may be achieved via distinct biochemical mechanisms that yield a similar functional outcome.

Sedimentation equilibrium of human low density lipoprotein subfractions.

The molecular weights of low density lipoprotein (LDL) subfractions were determined precisely by meniscus depletion sedimentation equilibrium. Equilibrium speeds ranged from 9743 to 5896 rpm. The average molecular weights of various LDL subfractions of Sf values 9.49, 7.94, 6.42, 5.17, and 3.71 determined by sedimentation equilibrium were 2.97 X 10(6) ; 3.13 X 10(6); 2.89 X 10(6); 2.45 X 10(6); and 2.61 X 10(6) daltons, respectively; and their respective densities were 1.0267, 1.0306, 1.0358, 1.0422, and 1.0492 g/ml. Minimal hydrated molecular weights for this fractions determined by flotation velocity at 37,020 rpm were 2.57 X 10(6); 2.37 X 10(6); 2.09 X 10(6); 1.94 X 10(6); and 1.81 X 10(6) daltons; whereas similar molecular weights determined at 52,640 rpm were 2.53 X 10(6); 2.27 X 10(6); 1.99 X 10(6); 1.86 X 10(6); and 1.74 X 10(6) daltons for the respective LDL subfractions. Higher molecular weights of fractions 2 and 5 compared to their adjacent fractions 1 and 4 by sedimentation equilibrium are of great interest. The calculated fractional ratio f/f O from sedimentation equilibrium and flotation velocity data ranges from 1.10 to 1.31, suggesting complexity and asymmetry of LDL subfraction molecules. There is also evidence that compressibility of LDL molecules may be different than that for the salt solution under high g-force. Assuming that redistributed LDL molecules at equilibrium under low g-force are spherical, it is possible that the shape of LDL molecules undergoing flotation velocity determinations may be distorted in high g-force conditions. Such distortion may be consistent with the high f/f O values obtained and may also be a basis for structural rearrangement and/or lipoprotein degradation with prolonged preparative ultracentrifugation at high g-force and pressure.

Revisiting the concept of cancer stem cells in prostate cancer.

The cancer stem cell (CSC) model proposes that cells within a tumor are organized in a hierarchical lineage relationship and display different tumorigenic potential, suggesting that effective therapeutics should target rare CSCs that sustain tumor malignancy. Here we review the current status of studies to identify CSCs in human prostate cancer as well as mouse models, with an emphasis on discussing different functional assays and their advantages and limitations. We also describe current controversies regarding the identification of prostate epithelial stem cells and cell types of origin for prostate cancer, and present potential resolutions of these issues. Although definitive evidence for the existence of CSCs in prostate cancer is still lacking, future directions pursuing the identification of tumor-initiating stem cells in the mouse may provide important advances in evaluating the CSC model for prostate cancer.