Sexes show differential tolerance to spittlebug damage and consequences of damage for multi-species interactions

Antagonists can play a role in sexual system evolution if tolerance or resistance is sex-dependent. Our understanding of this role will be enhanced by consideration of the effects of antagonists on other plant-animal interactions. This study determined whether the sex morphs of a gynodioecious Fragaria virginiana differ in their susceptibility and response to damage by spittlebugs and whether damage altered pollinator attraction traits or interactions with other antagonists. Tolerance, but not resistance, to spittlebugs differed between the sexes. Generally, spittlebugs were more damaging to hermaphrodites than females, a finding in accord with the hypothesis that the pollen-bearing morph is less tolerant of source-damage than the pollen-sterile morph when damage is incurred during flowering. In both sex morphs, spittlebugs reduced inflorescence height, increased petal size, but did not affect the number of open flowers per day, suggesting that the net effect of damage may be to increase pollinator attraction. Spittlebug infestation modified interactions with other antagonists in a sex-dependent manner: spittlebugs reduced attack by bud-clipping weevils in hermaphrodites but increased infection by leaf fungi in females. The complex interactions between plant sex, antagonists, and pollinator attraction documented here emphasize the importance of considering sex-differential multi-species interactions in plant sexual evolution.     

Severely incapacitating mutations in patients with extreme short stature identify RNA-processing endoribonuclease RMRP as an essential cell growth regulator

The growth of an individual is deeply influenced by the regulation of cell growth and division, both of which also contribute to a wide variety of pathological conditions, including cancer, diabetes, and inflammation. To identify a major regulator of human growth, we performed positional cloning in an autosomal recessive type of profound short stature, anauxetic dysplasia. Homozygosity mapping led to the identification of novel mutations in the RMRP gene, which was previously known to cause two milder types of short stature with susceptibility to cancer, cartilage hair hypoplasia, and metaphyseal dysplasia without hypotrichosis. We show that different RMRP gene mutations lead to decreased cell growth by impairing ribosomal assembly and by altering cyclin-dependent cell cycle regulation. Clinical heterogeneity is explained by a correlation between the level and type of functional impairment in vitro and the severity of short stature or predisposition to cancer. Whereas the cartilage hair hypoplasia founder mutation affects both pathways intermediately, anauxetic dysplasia mutations do not affect B-cyclin messenger RNA (mRNA) levels but do severely incapacitate ribosomal assembly via defective endonucleolytic cleavage. Anauxetic dysplasia mutations thus lead to poor processing of ribosomal RNA while allowing normal mRNA processing and, therefore, genetically separate the different functions of RNase MRP.     

Population structure, admixture, and aging-related phenotypes in African American adults: the Cardiovascular Health Study

U.S. populations are genetically admixed, but surprisingly little empirical data exists documenting the impact of such heterogeneity on type I and type II error in genetic-association studies of unrelated individuals. By applying several complementary analytical techniques, we characterize genetic background heterogeneity among 810 self-identified African American subjects sampled as part of a multisite cohort study of cardiovascular disease in older adults. On the basis of the typing of 24 ancestry-informative biallelic single-nucleotide-polymorphism markers, there was evidence of substantial population substructure and admixture. We used an allele-sharing-based clustering algorithm to infer evidence for four genetically distinct subpopulations. Using multivariable regression models, we demonstrate the complex interplay of genetic and socioeconomic factors on quantitative phenotypes related to cardiovascular disease and aging. Blood glucose level correlated with individual African ancestry, whereas body mass index was associated more strongly with genetic similarity. Blood pressure, HDL cholesterol level, C-reactive protein level, and carotid wall thickness were not associated with genetic background. Blood pressure and HDL cholesterol level varied by geographic site, whereas C-reactive protein level differed by occupation. Both ancestry and genetic similarity predicted the number and quality of years lived during follow-up, but socioeconomic factors largely accounted for these associations. When the 24 genetic markers were tested individually, there were an excess number of marker-trait associations, most of which were attenuated by adjustment for genetic ancestry. We conclude that the genetic demography underlying older individuals who self identify as African American is complex, and that controlling for both genetic admixture and socioeconomic characteristics will be required in assessing genetic associations with chronic-disease-related traits in African Americans. Complementary methods that identify discrete subgroups on the basis of genetic similarity may help to further characterize the complex biodemographic structure of human populations.     

Genotype-phenotype associations in Sotos syndrome: an analysis of 266 individuals with NSD1 aberrations

We identified 266 individuals with intragenic NSD1 mutations or 5q35 microdeletions encompassing NSD1 (referred to as "NSD1-positive individuals"), through analyses of 530 subjects with diverse phenotypes. Truncating NSD1 mutations occurred throughout the gene, but pathogenic missense mutations occurred only in functional domains (P < 2 x 10(-16)). Sotos syndrome was clinically diagnosed in 99% of NSD1-positive individuals, independent of the molecular analyses, indicating that NSD1 aberrations are essentially specific to this condition. Furthermore, our data suggest that 93% of patients who have been clinically diagnosed with Sotos syndrome have identifiable NSD1 abnormalities, of which 83% are intragenic mutations and 10% are 5q35 microdeletions. We reviewed the clinical phenotypes of 239 NSD1-positive individuals. Facial dysmorphism, learning disability, and childhood overgrowth were present in 90% of the individuals. However, both the height and head circumference of 10% of the individuals were within the normal range, indicating that overgrowth is not obligatory for the diagnosis of Sotos syndrome. A broad spectrum of associated clinical features was also present, the occurrence of which was largely independent of genotype, since individuals with identical mutations had different phenotypes. We compared the phenotypes of patients with intragenic NSD1 mutations with those of patients with 5q35 microdeletions. Patients with microdeletions had less-prominent overgrowth (P = .0003) and more-severe learning disability (P = 3 x 10(-9)) than patients with mutations. However, all features present in patients with microdeletions were also observed in patients with mutations, and there was no correlation between deletion size and the clinical phenotype, suggesting that the deletion of additional genes in patients with 5q35 microdeletions has little specific effect on phenotype. We identified only 13 familial cases. The reasons for the low vertical transmission rate are unclear, although familial cases were more likely than nonfamilial cases (P = .005) to carry missense mutations, suggesting that the underlying NSD1 mutational mechanism in Sotos syndrome may influence reproductive fitness.     

Effects of acute and chronic coingestion of AlCl3 with citrate or polyphenolic acids on tissue retention and distribution of aluminum in rats

Aluminum (Al) is toxic to certain biological systems and has been implicated as a neurotoxic agent in the pathogenesis of Alzheimer’s disease. Intestinal absorption of Al is very low (0.1%), but many organic dietary components are potential chelators of Al and may enhance its absorption and tissue distribution. We examined the effects of acute and chronic coingestion of AlCl₃ with different polyphenolic acids on Al retention and compared to citrate in rats. In experiment 1, animals fasted for 14 h were dosed orally with demineralized water, Al chloride, Al chloride plus sodium citrate, or Al chloride plus a polyphenol acid. Blood samples were taken before and 2 h after the gavage and animals were killed 6 h later. In experiment 2, the rats were adapted on a purified diet for 1 wk and received the following for 4 wk in their experimental diets: AlCl₃, except group 1, plus citrate or a polyphenol acid, except groups 1 and 2. Animals were killed and blood and tissues were sampled. In experiment 1, citrate highly enhanced Al absorption and its tissue retention. Gallic and chlorogenic acids significantly increased tibia and kidney Al levels compared to the Al group. In experiment 2, Al levels in the urine were significantly increased in all the Al groups compared to the control group. Significantly higher Al levels in the tibia, kidney, and brain were observed in the citrate group and a significant increase in brain Al level was also noted in the chlorogenic acid group compared to AlCl₃ group. This may suggest a possible relation structure-activity of polyphenol acids. However, further studies are necessary to better understand the influence of polyphenol acids on Al metabolism, in particular that of chlorogenic acid.     

Light quality influences the polyamine content of lettuce (Lactuca sativa L.) cotyledon explants during shoot production <Emphasis Type="Italic">in vitro</Emphasis>

Light quality has previously been shown to influence morphogenesis in lettuce cotyledon explants, with white or red light promoting adventitious shoot production, and blue light inhibiting it. Endogenous polyamine (PA) concentrations were compared between explants cultured under different light qualities. Explants cultured under white or red light accumulated PAs during shoot primordia production, with a 5.6-fold increase compared to initial concentrations under white light, and 6.7-fold increase under red light. These results suggest polyamines are involved in the formation of shoot primordia. After 18 days in culture PA concentrations decreased under white light, and to a lesser extent under red light, signaling a shift in polyamine metabolism that correlates with shoot expansion, which occurs more readily under white light. Explants cultured under blue light accumulated polyamines for the first 7 days, to a level 1.3 times greater than initial values, followed by a gradual decline during the remainder of the culture period. Explants cultured under blue light also contained a greater proportion of PCA-insoluble conjugated PAs, compared to explants under white or red light, which contained greater proportions of free or PCA-soluble conjugated polyamines. The ratio of putrescine to spermidine was also different with a lower Put:Spd ratio being associated with shoot production under white or red light, and higher Put:Spd ratio being associated with culture under blue light.     

Suppressor of cytokine signaling-2 modulates the fibrogenic actions of GH and IGF-I in intestinal mesenchymal cells

Growth hormone (GH) and IGF-I play important roles in wound healing during intestinal injury and inflammation, but there is also indirect evidence that locally expressed IGF-I may act to induce excessive collagen deposition, which can lead to intestinal fibrosis. Factors that dictate the balance between normal wound healing and excessive healing responses are unknown. Using RNase protection assay and in situ hybridization, we determined whether GH and/or IGF-I increase type I collagen deposition in the intestine of rats fed by total parenteral nutrition (TPN), a feeding modality used for many patients following intestinal surgery and resection. We also used an in vitro model system to confirm our in vivo effects and to directly evaluate the relative potency of GH and IGF-I on DNA synthesis and collagen deposition in intestinal myofibroblasts. Both GH and IGF-I stimulated collagen production in vivo and in vitro, and IGF-I, but not GH, stimulated DNA synthesis in vitro. In collagen production, GH was less potent than IGF-I. Suppressors of cytokine signaling (SOC) are cytokine-inducible proteins that negatively feedback to inhibit the actions of cytokines and we recently found that GH selectively upregulates SOC-2 in the intestine of TPN-fed rats. We examined whether SOC-2 may be responsible for the difference in magnitude of action of GH and IGF-I on collagen accumulation. GH, but not IGF-I, induced SOC-2 in isolated myofibroblasts, and overexpression of SOC-2 led to a suppression of GH- and IGF-I-induced collagen accumulation. SOC-2 null mice infused with IGF-I showed greater collagen gene expression compared with wild-type (WT) mice. Myofibroblasts isolated from SOC-2 null mice showed increased IGF-I-stimulated DNA synthesis compared with WT cells. Taken together, these findings suggest that SOC-2 induced by GH may play an important role in suppressing collagen accumulation and mesenchymal cell proliferation induced by GH or GH-induced IGF-I, providing a mechanism for the differing potencies of GH and IGF-I on intestinal mesenchyme and collagen synthesis.     

Proteomic profiling of recombinant Escherichia coli in high-cell-density fermentations for improved production of an antibody fragment biopharmaceutical

By using two-dimensional polyacrylamide gel electrophoresis, a proteomic analysis over time was conducted with high-cell-density, industrial, phosphate-limited Escherichia coli fermentations at the 10-liter scale. During production, a recombinant, humanized antibody fragment was secreted and assembled in a soluble form in the periplasm. E. coli protein changes associated with culture conditions were distinguished from protein changes associated with heterologous protein expression. Protein spots were monitored quantitatively and qualitatively. Differentially expressed proteins were quantitatively assessed by using a t-test method with a 1% false discovery rate as a significance criterion. As determined by this criterion, 81 protein spots changed significantly between 14 and 72 h (final time) of the control fermentations (vector only). Qualitative (on-off) comparisons indicated that 20 more protein spots were present only at 14 or 72 h in the control fermentations. These changes reflected physiological responses to the culture conditions. In control and production fermentations at 72 h, 25 protein spots were significantly differentially expressed. In addition, 19 protein spots were present only in control or production fermentations at this time. The quantitative and qualitative changes were attributable to overexpression of recombinant protein. The physiological changes observed during the fermentations included the up-regulation of phosphate starvation proteins and the down-regulation of ribosomal proteins and nucleotide biosynthesis proteins. Synthesis of the stress protein phage shock protein A (PspA) was strongly correlated with synthesis of a recombinant product. This suggested that manipulation of PspA levels might improve the soluble recombinant protein yield in the periplasm for this bioprocess. Indeed, controlled coexpression of PspA during production led to a moderate, but statistically significant, improvement in the yield.     

Chronically elevated glucose-induced apoptosis is mediated by inactivation of Akt in cultured Müller cells

Hyperglycemia induces apoptotic cell death in a variety of cell types in diabetes, and the mechanism remains unclear. We report here that culture of rat retinal glial Müller cells in 25 mM glucose for 72 h significantly inactivated Akt and induced apoptosis. Likewise, hyperglycemia caused a significant dephosphorylation of Akt at serine-473 in Müller cells in the retina of streptozotocin-induced diabetic rats. Inactivation of Akt was associated with dephosphorylation of BAD, increased cytochrome c release, and activation of caspase-3 and caspase-9. Upregulation of Akt activity by overexpression of constitutively active Akt inhibited elevated glucose-induced apoptosis, whereas downregulation of Akt activity by overexpression of dominant negative Akt exacerbated elevated glucose-induced apoptosis, as assessed by caspase activity and nucleic acid staining. These data suggest that apoptosis induced by chronically elevated glucose is at least in part mediated by downregulation of Akt survival pathway in cultured Müller cells. It has been reported that antiapoptotic effect of Akt requires glucose in growth factor withdrawal-induced apoptosis. Our data suggest that although acutely elevated glucose may be beneficial to the cell survival, chronically elevated glucose can cause apoptosis via downregulation of Akt survival signaling.