A cell-based high-throughput screen identifies tyrphostin AG 879 as an inhibitor of animal cell phospholipid and fatty acid biosynthesis

Inhibition of animal cell phospholipid biosynthesis has been proposed for anticancer and antiviral therapies. Using CHOK1 derived cell lines, we have developed and used a cell-based high-throughput procedure to screen a 1280 compound, small molecule library for inhibitors of phospholipid biosynthesis. We identified tyrphostin AG 879 (AG879), which inhibited phospholipid biosynthesis by 85–90% at a concentration of 10 μM, displaying an IC₅₀ of 1–3 μM. The synthesis of all phospholipid head group classes was heavily affected. Fatty acid biosynthesis was also dramatically inhibited (90%). AG879 inhibited phospholipid biosynthesis in all additional cell lines tested, including MDCK, HUH7, Vero, and HeLa cell lines. In CHO cells, AG879 was cytostatic; cells survived for at least four days during exposure and were able to divide following its removal. AG879 is an inhibitor of receptor tyrosine kinases (RTK) and inhibitors of signaling pathways known to be activated by RTK's also inhibited phospholipid biosynthesis. We speculate that inhibition of RTK by AG879 results in an inhibition of fatty acid biosynthesis with a resulting decrease in phospholipid biosynthesis and that AG879's effect on fatty acid synthesis and/or phospholipid biosynthesis may contribute to its known capacity as an effective antiviral/anticancer agent.     

The interplay of RecA-related proteins and the MND1-HOP2 complex during meiosis in Arabidopsis thaliana

During meiosis, homologous chromosomes recognize each other, align, and exchange genetic information. This process requires the action of RecA-related proteins Rad51 and Dmc1 to catalyze DNA strand exchanges. The Mnd1-Hop2 complex has been shown to assist in Dmc1-dependent processes. Furthermore, higher eukaryotes possess additional RecA-related proteins, like XRCC3, which are involved in meiotic recombination. However, little is known about the functional interplay between these proteins during meiosis. We investigated the functional relationship between AtMND1, AtDMC1, AtRAD51, and AtXRCC3 during meiosis in Arabidopsis thaliana. We demonstrate the localization of AtMND1 to meiotic chromosomes, even in the absence of recombination, and show that AtMND1 loading depends exclusively on AHP2, the Arabidopsis Hop2 homolog. We provide evidence of genetic interaction between AtMND1, AtDMC1, AtRAD51, and AtXRCC3. In vitro assays suggest that this functional link is due to direct interaction of the AtMND1-AHP2 complex with AtRAD51 and AtDMC1. We show that AtDMC1 foci accumulate in the Atmnd1 mutant, but are reduced in number in Atrad51 and Atxrcc3 mutants. This study provides the first insights into the functional differences of AtRAD51 and AtXRCC3 during meiosis, demonstrating that AtXRCC3 is dispensable for AtDMC1 focus formation in an Atmnd1 mutant background, whereas AtRAD51 is not. These results clarify the functional interactions between key players in the strand exchange processes during meiotic recombination. Furthermore, they highlight a direct interaction between MND1 and RAD51 and show a functional divergence between RAD51 and XRCC3.     

Solution Structure of C. elegans UNC-6: A Nematode Paralogue of the Axon Guidance Protein Netrin-1

UNCoordinated-6 (UNC-6) was the first member of the netrin family to be discovered in Caenorhabditis elegans. With homology to human netrin-1, it is a key signaling molecule involved in directing axon migration in nematodes. Similar to netrin-1, UNC-6 interacts with multiple receptors (UNC-5 and UNC-40, specifically) to guide axon migration in development. As a result of the distinct evolutionary path of UNC-6 compared to vertebrate netrins, we decided to employ an integrated approach to study its solution behavior and compare it to the high-resolution structure we previously published on vertebrate netrins. Dynamic light scattering and analytical ultracentrifugation on UNC-6 (with and without its C-domain) solubilized in a low-ionic strength buffer suggested that UNC-6 forms high-order oligomers. An increase in the buffer ionic strength resulted in a more homogeneous preparation of UNC-6, that was used for subsequent solution x-ray scattering experiments. Our biophysical analysis of UNC-6 ΔC solubilized in a high-ionic strength buffer suggested that it maintains a similar head-to-stalk arrangement as netrins ?1 and ?4. This phenomenon is thought to play a role in the signaling behavior of UNC-6 and its ability to move throughout the extracellular matrix.     

Length–weight relationships of four freshwater fish species from two Atlantic coastal drainage areas in Brazil

Length–weight relationships (LWRs) were determined for four fish species from two drainage areas, those of the Itapemirim and Jucu River, in the state of Espírito Santo, southeastern Brazil. Fishes were collected between May 2015 and November 2016, with gill nets, casting net, dip net, and sieve. Herein are presented LWRs for Astyanax lacustris, Astyanax taeniatus, Hyphessobrycon bifasciatus and Oligosarcus acutirostris.     

Scalable remote homology detection and fold recognition in massive protein networks

The global connectivities in very large protein similarity networks contain traces of evolution among the proteins for detecting protein remote evolutionary relations or structural similarities. To investigate how well a protein network captures the evolutionary information, a key limitation is the intensive computation of pairwise sequence similarities needed to construct very large protein networks. In this article, we introduce label propagation on low-rank kernel approximation (LP-LOKA) for searching massively large protein networks. LP-LOKA propagates initial protein similarities in a low-rank graph by Nyström approximation without computing all pairwise similarities. With scalable parallel implementations based on distributed-memory using message-passing interface and Apache-Hadoop/Spark on cloud, LP-LOKA can search protein networks with one million proteins or more. In the experiments on Swiss-Prot/ADDA/CASP data, LP-LOKA significantly improved protein ranking over the widely used HMM-HMM or profile-sequence alignment methods utilizing large protein networks. It was observed that the larger the protein similarity network, the better the performance, especially on relatively small protein superfamilies and folds. The results suggest that computing massively large protein network is necessary to meet the growing need of annotating proteins from newly sequenced species and LP-LOKA is both scalable and accurate for searching massively large protein networks.     

Parasitism of Hypothenemus hampei (Coleoptera: Scolytidae) in different farming systems and altitudes of Mount Elgon,Uganda

Altitude and farming system play a vital role in modifying the niche for arthropods, by directly influencing microclimatic conditions, the quality and quantity of vegetative cover, which act variably on the behaviour of the pests, and their natural enemies. The objective of the study was to determine their effect on the abundance and parasitism of the Coffee berry borer (Hypothenemus hampei) in the Mount Elgon region. Altitude was categorized as: low (1,400–1,499 m.a.s.l); mid (1,500‐1,679 m.a.s.l); and high (1,680–2,100 m.a.s.l), and farming system was categorized as: Coffee monocrop; Coffee + annual; Coffee + banana; and Coffee + banana + shade trees. For each altitudinal range, each farming system was represented three times. The study was in two districts of the Mt. Elgon, covering a total of 72 Arabica Coffee study sites. The work involved field pest infestation inventories, followed by laboratory rearing for the abundance and parasitism studies. The results revealed highly significant interactions between altitude and farming system in influencing the abundance of the pest and its four parasitoids: Phymastichus coffea, Cephalonomia stephanoderis, Prorops nasuta and Heterospilus coffeicola. C. stephanoderis was highest in the mid‐altitudes within Coffee + banana+shade tree system; P. nasuta was highest at high altitude within Coffee + banana system; P. coffea was most abundant at mid‐altitude within Coffee + banana system, whereas H. coffeicola was highest at high altitude within the Coffee + annual cropping system. H. hampei counts were highest at low altitudes, especially in the Coffee + annual system. Some of these trends can be explained by the condition of the microclimate in the Coffee fields. There was a negative relationship between temperature and abundance of all the four parasitoids. Only C. stephanoderis had a relationship (+) with semi‐natural vegetation species counts. And only H. coffeicola had a relationship (+) with light intensity. These contrasted with H. hampei, which was positively related to temperature and negatively to light intensity.     

Sex bodies and synaptonemal complexes of Balb/C mice: antioxidant intervention of oxyradical insult

Spermatogenesis is inhibited in Balb/C mice as a result of oxyradical insult. However, mammalian spermatocytes and synaptonemal complexes retain their structure and function after oxyradical insult due to protection afforded by the antioxidant vitamin E. Control groups were compared with experimental groups which were fed various vitamin E-deficient diets and subjected to varying times in an humidified 100% oxygen (hyperoxia) chamber. Measurements were made of sex body volume (SBV), nuclear envelope aberrations (NEA), and synaptonemal complex structure in spermatocytes during pachytene of meiosis prophase I. Changes in the volume of the sex body were positively correlated with increased oxyradical insult. The structure of the synaptonemal complex was not altered in any of the experimental groups which is a significant observation. It is suggested that vitamin E affords antioxidant protection and inhibits the alteration of membranes and sex chromosomes in mice during meiosis.     

Gorillas with spondyloarthropathies express an MHC class I molecule with only limited sequence similarity to HLA-B27 that binds peptides with arginine at P2

The human MHC class I gene, HLA-B27, is a strong risk factor for susceptibility to a group of disorders termed spondyloarthropathies (SpAs). HLA-B27-transgenic rodents develop SpAs, implicating HLA-B27 in the etiology of these disorders. Several nonhuman primates, including gorillas, develop signs of SpAs indistinguishable from clinical signs of humans with SpAs. To determine whether SpAs in gorillas have a similar HLA-B27-related etiology, we analyzed the MHC class I molecules expressed in four affected gorillas. Gogo-B01, isolated from three of the animals, has only limited similarity to HLA-B27 at the end of the alpha1 domain. It differs by several residues in the B pocket, including differences at positions 45 and 67. However, the molecular model of Gogo-B*0101 is consistent with a requirement for positively charged residues at the second amino acid of peptides bound by the MHC class I molecule. Indeed, the peptide binding motif and sequence of individual ligands eluted from Gogo-B*0101 demonstrate that, like HLA-B27, this gorilla MHC class I molecule binds peptides with arginine at the second amino acid position of peptides bound by the MHC class I molecule. Furthermore, live cell binding assays show that Gogo-B*0101 can bind HLA-B27 ligands. Therefore, although most gorillas that develop SpAs express an MHC class I molecule with striking differences to HLA-B27, this molecule binds peptides similar to those bound by HLA-B27.