Dietary Response of Chimpanzees and Cercopithecines to Seasonal Variation in Fruit Abundance. II. Macronutrients

In a continuation of our study of dietary differentiation among frugivorous primates with simple stomachs, we present the first comparison of differences in dietary macronutrient content between chimpanzees and cercopithecine monkeys. Previously we have shown that chimpanzee and monkey diets differ markedly in plant part and species content. We now examine whether this diet diversity is reflected in markedly different dietary macronutrient levels or the different feeding strategies yield the same macronutrient levels in their diets. For each primate group we calculated the total weighted mean dietary content of 4 macronutrients: crude lipid (lipid), crude protein (CP), water-soluble carbohydrates (WSC), and total nonstructural carbohydrates (TNC). We also calculated 4 fiber fractions: neutral-detergent fiber (NDF), which includes the subfractions hemicellulose (HC), cellulose (Cs), and sulfuric acid lignin (Ls). The HC and Cs are potentially fermentable fibers and would contribute to the energy provided by plant food, depending on the hind gut fermenting capacity of the individual primate species. The chimpanzee diet contained higher levels of WSC and TNC because during times of fruit abundance the chimpanzees took special advantage of ripe fruit, while the monkeys did not. The monkey diets contained higher levels of CP because the monkeys consumed a constant amount of leaf throughout the year. All four primate species consumed diets with similar NDF levels. However, the chimpanzees also took advantage of periods of ripe fruit abundance to decrease their Ls levels and to increase their HC levels. Conversely, the monkey diets maintained constant levels of the different fiber fractions thoughout the year. Nevertheless, despite these differences, the diets of the 4 frugivores were surprisingly similar, considering the substantial differences in body size. We conclude that the chimpanzee diet is of higher quality, particularly of lower fiber content, than expected on the basis of their body size.     

Regulation of Alternative Polyadenylation by U1 snRNPs and SRp20

Although considerable information is currently available about the factors involved in constitutive vertebrate polyadenylation, the factors and mechanisms involved in facilitating communication between polyadenylation and splicing are largely unknown. Even less is known about the regulation of polyadenylation in genes in which 3′-terminal exons are alternatively recognized. Here we demonstrate that an SR protein, SRp20, affects recognition of an alternative 3′-terminal exon via an effect on the efficiency of binding of a polyadenylation factor to an alternative polyadenylation site. The gene under study codes for the peptides calcitonin and calcitonin gene-related peptide. Its pre-mRNA is alternatively processed by the tissue-specific inclusion or exclusion of an embedded 3′-terminal exon, exon 4, via factors binding to an intronic enhancer element that contains both 3′ and 5′ splice site consensus sequence elements. In cell types that preferentially exclude exon 4, addition of wild-type SRp20 enhances exon 4 inclusion via recognition of the intronic enhancer. In contrast, in cell types that preferentially include exon 4, addition of a mutant form of SRp20 containing the RNA-binding domain but missing the SR domain inhibits exon 4 inclusion. Inhibition is likely at the level of polyadenylation, because the mutant SRp20 inhibits binding of CstF to the exon 4 poly(A) site. This is the first demonstration that an SR protein can influence alternative polyadenylation and suggests that this family of proteins may play a role in recognition of 3′-terminal exons and perhaps in the communication between polyadenylation and splicing.     

Synthesis and properties of triplex-forming oligonucleotides containing 2′-O-(2-methoxyethyl)-5-(3-aminoprop-1-ynyl)-uridine

2′-O-(2-Methoxyethyl)-5-(3-aminoprop-1-ynyl)-uridine phosphoramidite (MEPU) has been synthesized from d-ribose and 5-iodouracil and incorporated into triplex-forming oligonucleotides (TFOs) by automated solid-phase oligonucleotide synthesis. The TFOs gave very high triplex stability with their target duplexes as measured by ultraviolet/fluorescence melting and DNase I footprinting. The incorporation of MEPU into TFOs renders them resistant to degradation by serum nucleases.     

Secondary Metabolites from Aspergillus fumigatus,an Endophytic Fungus from the Liverwort Heteroscyphus tener (Steph.) Schiffn.

Three new metabolites, asperfumigatin ( 1 ), isochaetominine ( 10 ), and 8′‐O‐methylasterric acid ( 21 ), together with nineteen known compounds, were obtained from the culture of Aspergillus fumigatus, an endophytic fungus from the Chinese liverwort Heteroscyphus tener (Steph.) Schiffn. Their structures were established by extensive analysis of the spectroscopic data. The absolute configurations of 1 and 10 were determined by analysis of their respective CD spectra. Cytotoxicity of these isolates against four human cancer cell lines was also determined.     

New insights into iron acquisition by cyanobacteria: an essential role for ExbB-ExbD complex in inorganic iron uptake

Cyanobacteria are globally important primary producers that have an exceptionally large iron requirement for photosynthesis. In many aquatic ecosystems, the levels of dissolved iron are so low and some of the chemical species so unreactive that growth of cyanobacteria is impaired. Pathways of iron uptake through cyanobacterial membranes are now being elucidated, but the molecular details are still largely unknown. Here we report that the non-siderophore-producing cyanobacterium Synechocystis sp. PCC 6803 contains three exbB-exbD gene clusters that are obligatorily required for growth and are involved in iron acquisition. The three exbB-exbDs are redundant, but single and double mutants have reduced rates of iron uptake compared with wild-type cells, and the triple mutant appeared to be lethal. Short-term measurements in chemically well-defined medium show that iron uptake by Synechocystis depends on inorganic iron (Fe′) concentration and ExbB-ExbD complexes are essentially required for the Fe′ transport process. Although transport of iron bound to a model siderophore, ferrioxamine B, is also reduced in the exbB-exbD mutants, the rate of uptake at similar total [Fe] is about 800-fold slower than Fe′, suggesting that hydroxamate siderophore iron uptake may be less ecologically relevant than free iron. These results provide the first evidence that ExbB-ExbD is involved in inorganic iron uptake and is an essential part of the iron acquisition pathway in cyanobacteria. The involvement of an ExbB-ExbD system for inorganic iron uptake may allow cyanobacteria to more tightly maintain iron homeostasis, particularly in variable environments where iron concentrations range from limiting to sufficient.     

Placental Fatty Acid Ethyl Esters Are Elevated with Maternal Alcohol Use in Pregnancies Complicated by Prematurity

The accumulation of fatty acid ethyl esters (FAEEs) in meconium of term newborns has been described as one potential biomarker of maternal alcohol use during pregnancy. FAEEs accumulate in multiple alcohol-exposed fetal tissues and in the placenta. Limited research has focused on the identification of the premature newborn exposed to alcohol in utero. We hypothesized that maternal alcohol use occurs in a significant proportion of premature deliveries and that this exposure can be detected as elevated placental FAEEs. The goals of this study were to 1) determine the prevalence of maternal alcohol use in the premature newborn and 2) investigate whether placental FAEEs could identify those newborns with fetal alcohol exposure. This prospective observational study evaluated 80 placentas from 80 women after premature delivery. Subjects were interviewed for alcohol intake and placental FAEEs were quantified via GC/MS. Receiver Operator Characteristic (ROC) Curves were generated to evaluate the ability of placental FAEEs to predict maternal drinking during pregnancy. Adjusted ROC curves were generated to adjust for gestational age, maternal smoking, and illicit drug use. 30% of the subjects admitted to drinking alcohol during pregnancy and approximately 14% answered questions indicative of problem drinking (designated AUDIT+). The specific FAEEs ethyl stearate and linoleate, as well as combinations of oleate + linoleate + linolenate (OLL) and of OLL + stearate, were significantly (p<0.05) elevated in placentas from AUDIT+ pregnancies. Adjusted ROC Curves generated areas under the curve ranging from 88–93% with negative predictive values of 97% for AUDIT+ pregnancies. We conclude that nearly one third of premature pregnancies were alcohol-exposed, and that elevated placental FAEEs hold great promise to accurately determine maternal alcohol use, particularly heavy use, in pregnancies complicated by premature delivery.     

SGO1C is a non-functional isoform of Shugoshin and can disrupt sister chromatid cohesion by interacting with PP2A–B56

Shugoshin (SGO1) plays a pivotal role in sister chromatid cohesion during mitosis by protecting the centromeric cohesin from mitotic kinases and WAPL. Mammalian cells contain at least 6 alternatively spliced isoforms of SGO1. The relationship between the canonical SGO1A with shorter isoforms including SGO1C remains obscure. Here we show that SGO1C was unable to replace the loss of SGO1A. Instead, expression of SGO1C alone induced aberrant mitosis similar to depletion of SGO1A, promoting premature sister chromatid separation, activation of the spindle-assembly checkpoint, and mitotic arrest. In disagreement with previously published data, we found that SGO1C localized to kinetochores. However, the ability to induce aberrant mitosis did not correlate with its kinetochore localization. SGO1C mutants that abolished binding to kinetochores still triggered premature sister chromatid separation. We provide evidence that SGO1C-mediated mitotic arrest involved the sequestering of PP2A–B56 pool. Accordingly, SGO1C mutants that abolished binding to PP2A localized to kinetochores but did not induce aberrant mitosis. These studies imply that the expression of SGO1C should be tightly regulated to prevent dominant-negative effects on SGO1A and genome instability.