Chemically mediated mechanical expansion of the pollen tube cell wall

Morphogenesis of plant cells is tantamount to the shaping of the stiff cell wall that surrounds them. To this end, these cells integrate two concomitant processes: 1), deposition of new material into the existing wall, and 2), mechanical deformation of this material by the turgor pressure. However, due to uncertainty regarding the mechanisms that coordinate these processes, existing models typically adopt a limiting case in which either one or the other dictates morphogenesis. In this report, we formulate a simple mechanism in pollen tubes by which deposition causes turnover of cell wall cross-links, thereby facilitating mechanical deformation. Accordingly, deposition and mechanics are coupled and are both integral aspects of the morphogenetic process. Among the key experimental qualifications of this model are: its ability to precisely reproduce the morphologies of pollen tubes; its prediction of the growth oscillations exhibited by rapidly growing pollen tubes; and its prediction of the observed phase relationships between variables such as wall thickness, cell morphology, and growth rate within oscillatory cells. In short, the model captures the rich phenomenology of pollen tube morphogenesis and has implications for other plant cell types.     

Morphological characteristics of the uterus and uterine cervix of the plains viscacha (Lagostomus maximus)

The plains viscacha is a hystricognathi rodent with special reproductive characteristics. Despite poly-ovulation of 800 oocytes, it generates a high embryonic mortality since from 10 to 12 implantations only one or two offspring are born. The present work analyses the morphological, morphometrical, histochemical and lectinhistochemical characteristics of the uterus and uterine cervix of pregnant and non-pregnant viscacha. Anatomically, the uterus has two horns each one continued with a short cervix devoid of glands. The structure of the uterus is like that of other species; however, the proportion and size of its glands varies according to the physiological state. In viscacha, there is no uterine body and cervices cannot be differentiated externally. The formation of two sack bottoms is determined by the presence of a middle raphe in the cranial portion of the vagina. The so-described anatomy is different from that described in other hystricognathi such as guinea pig and coypu. The cervix presents two microscopically differentiable regions: the endocervix and the ectocervix lined by epithelia with different characteristics. The general characteristics of the uterus of L. maximus do not show specific differences with those of other mammals that might explain its peculiar gestation.     

Structure of plant–Hymenoptera networks in two coastal shrub sites in Mexico

The study of interaction networks between plants and pollinators allows us to explore interaction patterns at the community level, detect changes in visit frequency and evaluate the nestedness of the networks. The latter allows rare plant species to be visited by more abundant species of pollinators, potentially allowing community diversity to be maintained, and this approach makes it possible to discern the rewiring (changes in connections) of species when their preferred resource is not available. In this study, the topology, species identity and rewiring were compared between two contrasting sites, one within a conservation area and the other subjected to continuous disturbance. The networks of both sites were significantly nested and shared a high number of common species of both plants and pollinators. However, the sites differed notably in the number of exclusive interactions, suggesting a high percentage of interaction rewiring. The introduced bee species, Apis mellifera, was the most frequent species at both sites and also the most connected in terms of the number of its interactions. This is explained by its generalist foraging characteristics that allow it to form part of the networks’ core group. In general, our results underscore the importance of knowing the identity of the participating species when studying networks, and how connections change between them, as well as the potential effect of habitat destruction and the role of invasive species in the rearrangement of the interactions; all factors that can exert an influence on the functioning of plant–pollinator networks.     

BH3-Mimetics- and Cisplatin-Induced Cell Death Proceeds through Different Pathways Depending on the Availability of Death-Related Cellular Components

Background

Owing to their important function in regulating cell death, pharmacological inhibition of Bcl-2 proteins by dubbed BH3-mimetics is a promising strategy for apoptosis induction or sensitization to chemotherapy. However, the role of Apaf-1, the main protein constituent of the apoptosome, in the process has yet not been analyzed. Furthermore as new chemotherapeutics develop, the possible chemotherapy-induced toxicity to rapidly dividing normal cells, especially sensitive differentiated cells, has to be considered. Such undesirable effects would probably be ameliorated by selectively and locally inhibiting apoptosis in defined sensitive cells.

Methodology and Principal Findings

Mouse embryonic fibroblasts (MEFS) from Apaf-1 knock out mouse (MEFS KO Apaf-1) and Bax/Bak double KO (MEFS KO Bax/Bak), MEFS from wild-type mouse (MEFS wt) and human cervix adenocarcinoma (HeLa) cells were used to comparatively investigate the signaling cell death-induced pathways of BH3-mimetics, like ABT737 and GX15-070, with DNA damage-inducing agent cisplatin (cis-diammineplatinum(II) dichloride, CDDP). The study was performed in the absence or presence of apoptosis inhibitors namely, caspase inhibitors or apoptosome inhibitors. BH3-mimetic ABT737 required of Apaf-1 to exert its apoptosis-inducing effect. In contrast, BH3-mimetic GX15-070 and DNA damage-inducing CDDP induced cell death in the absence of both Bax/Bak and Apaf-1. GX15-070 induced autophagy-based cell death in all the cell lines analyzed. MEFS wt cells were protected from the cytotoxic effects of ABT737 and CDDP by chemical inhibition of the apoptosome through QM31, but not by using general caspase inhibitors.

Conclusions

BH3-mimetic ABT737 not only requires Bax/Bak to exert its apoptosis-inducing effect, but also Apaf-1, while GX15-070 and CDDP induce different modalities of cell death in the absence of Bax/Bak or Apaf-1. Inclusion of specific Apaf-1 inhibitors in topical and well-localized administrations, but not in systemic ones, to avoid interferences with chemotherapeutics would be of interest to prevent chemotherapeutic-induced unwanted cell death which could improve cancer patient care.     

Two Functional Variants of IRF5 Influence the Development of Macular Edema in Patients with Non-Anterior Uveitis

Objective

Interferon (IFN) signaling plays a crucial role in autoimmunity. Genetic variation in interferon regulatory factor 5 (IRF5), a major regulator of the type I interferon induction, has been associated with risk of developing several autoimmune diseases. In the current study we aimed to evaluate whether three sets of correlated IRF5 genetic variants, independently associated with SLE and with different functional roles, are involved in uveitis susceptibility and its clinical subphenotypes.

Methods

Three IRF5 polymorphisms, rs2004640, rs2070197 and rs10954213, representative of each group, were genotyped using TaqMan® allelic discrimination assays in a total of 263 non-anterior uveitis patients and 724 healthy controls of Spanish origin.

Results

A clear association between two of the three analyzed genetic variants, rs2004640 and rs10954213, and the absence of macular edema was observed in the case/control analysis (P _FDR=5.07E-03, OR=1.48, CI 95%=1.14-1.92 and P _FDR=3.37E-03, OR=1.54, CI 95%=1.19-2.01, respectively). Consistently, the subphenotype analysis accordingly with the presence/absence of this clinical condition also reached statistical significance (rs2004640: P=0.037, OR=0.69, CI 95%=0.48-0.98; rs10954213: P=0.030, OR=0.67, CI 95%=0.47-0.96), thus suggesting that both IRF5 genetic variants are specifically associated with the lack of macular edema in uveitis patients.

Conclusion

Our results clearly showed for the first time that two functional genetic variants of IRF5 may play a role in the development of macular edema in non-anterior uveitis patients. Identifying genetic markers for macular edema could lead to the possibility of developing novel treatments or preventive therapies.     

Potential predation of non-webbuilding spider assemblage on cotton pests Helicoverpa armigera and Spodoptera littoralis (Lepidoptera: Noctuidae)

The relative feeding rates and preferences of a hunting-spider assemblage inhabiting southern Spanish cotton fields for two major cotton pests, Helicoverpa armigera (Hübner) and Spodoptera littoralis (Boisdubal) (Lepidoptera: Noctuidae), were analyzed under laboratory conditions. First, a no-choice feeding test was used to determine relative feeding rates for hunting-spider families and species, offering a fixed number of 10 neonate larvae of H. armigera or S. littoralis and observing predation after 2 h, 4 h, 8 h, and 24 h. In a second test, Drosophila melanogaster, a very palatable alternative prey, was used to determine the degree of preference for cotton pest larvae. The mean number of first-instar lepidoptera larvae consumed by hunting spiders after 24 h was 8.57±0.25. As expected, spiders showed no preference for either of the two cotton pest species H. armigera and S. littoralis over the other. Results also showed that cursorial spiders of the families Miturigidae (represented here by Cheiracanthium pelasgicum) and Philodromidae consumed significantly higher percentages of larvae than crab spiders belonging to the Thomisidae family after 2 h and 24 h, respectively. In the prey choice test, Cheiracantium pelasgicum displayed a strong preference for cotton pest larvae while Thomisidae and Oxyopidae showed no significant preference. In addition, as the attack sequence progressed, Ch. pelasgicum showed a clear tendency towards the alternation of prey while Thomisidae, and more irregularly Oxyopidae, maintained their preference for D. melanogaster. These findings confirmed both the considerable potential value of some cursorial spiders (e.g. Ch. pelasgicum) in the biological control of lepidopteran cotton pests and the relatively low impact of other hunting spiders, e.g. Thomisidae, on pests of this kind.     

Synthesis and anticonvulsant activity of bioisosteres of trimethadione,N-derivative-1,2,3-oxathiazolidine-4-one-2,2-dioxides from α-hydroxyamides

The synthesis and anticonvulsant activity of novel heterocycles N-derivative-1,2,3-oxathiazolidine-4-one-2,2-dioxides, bioisosteres of trimethadione (TMD, oxazolidine-2,4-dione) and phenytoin (PHE), are described. TMD is an anticonvulsant drug widely used against absences seizures in the early 80’s and PHE is an antiepileptic drug with a wide spectrum activity. The intermediates of synthesis of N-derivative-1,2,3-oxathiazolidine-4-one-2,2-dioxides, α-hydroxyamides, were obtained using microwave assisted synthesis. Anticonvulsant screening was performed in mice after intraperitoneal administration in the maximal electroshock seizure test (MES) and subcutaneous pentylenetetrazole seizures test (scPTZ). These new compounds showed a wide spectrum activity and were no neurotoxic in the RotoRod test. α-Hydroxyamides and N-derivative-1,2,3-oxathiazolidine-4-one-2,2-dioxides were 3–4700 times more potent than valproic acid in the MES test. Quantification of anticonvulsant protection was calculated (ED₅₀) for the most active candidates; α-hydroxyamides 3a–c and 3e, and N-derivative-oxathiazolidine-4-one-2,2-dioxides 5a–c with ED₅₀ values of 9.1, 53.9, 44.6, 25.2, 15.1, 91.1 and 0.06 mg/kg, respectively, in the MES test.