The influence of crop rotation on the onset of early blight (Alternaria solani)

Field experiments were carried out in 2016 and 2017 to determine the effect of crop rotation on the onset of early blight in three potato varieties in Denmark. Six and seven fields with different histories with potato (rotation‐fields) were used for the experiments in 2016 and 2017, respectively. The results showed that variety and the interaction between variety and rotation‐field had no significant effect on the onset of early blight. Rotation‐field, on the other hand, had a significant effect on the onset of early blight in both years of the study. Early blight occurred earlier in fields with <2 years between subsequent potato crops than in fields where potatoes have not been grown for at least 2 years. The onset of early blight was not different between the fields where there had not been potatoes for at least 2 years. For fields that were preceded by potatoes, early blight occurred earlier in fields in which the severity of early blight in the previous years was higher than that in the fields in which the severity of early blight in the previous years was low or moderate. In conclusion, the results of this study suggest that at least a 2‐year interval between subsequent potatoes in a rotation cycle is necessary to delay the onset of early blight. Moreover, the severity of early blight in the previous years can affect the onset of early blight.     

Proline-specific aminopeptidase P prevents replication-associated genome instability

Genotoxic stress during DNA replication constitutes a serious threat to genome integrity and causes human diseases. Defects at different steps of DNA metabolism are known to induce replication stress, but the contribution of other aspects of cellular metabolism is less understood. We show that aminopeptidase P (APP1), a metalloprotease involved in the catabolism of peptides containing proline residues near their N-terminus, prevents replication-associated genome instability. Functional analysis of C. elegans mutants lacking APP-1 demonstrates that germ cells display replication defects including reduced proliferation, cell cycle arrest, and accumulation of mitotic DSBs. Despite these defects, app-1 mutants are competent in repairing DSBs induced by gamma irradiation, as well as SPO-11-dependent DSBs that initiate meiotic recombination. Moreover, in the absence of SPO-11, spontaneous DSBs arising in app-1 mutants are repaired as inter-homologue crossover events during meiosis, confirming that APP-1 is not required for homologous recombination. Thus, APP-1 prevents replication stress without having an apparent role in DSB repair. Depletion of APP1 (XPNPEP1) also causes DSB accumulation in mitotically-proliferating human cells, suggesting that APP1’s role in genome stability is evolutionarily conserved. Our findings uncover an unexpected role for APP1 in genome stability, suggesting functional connections between aminopeptidase-mediated protein catabolism and DNA replication.     

Silent glutamatergic synapses in the mammalian brain

Excitatory synaptic transmission in the mammalian brain is mediated primarily by alpha-amino-3-hydroxy-5-methylisoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptors that are thought to be co-localized at individual synapses. However, recent electrophysiological and anatomical data suggest that the synaptic localization of AMPA and NMDA receptors may be independently regulated by neural activity. These data are reviewed here and the implications of these findings for the mechanisms underlying synaptic plasticity are discussed.     

Plasma micronutrient concentrations in infants undergoing therapy for phenylketonuria

Twenty-seven infants with classical phenylketonuria were evaluated longitudinally for 6 mo while ingesting Phenex^TM -1 Amino Acid Modified Medical Food With Iron as their primary protein source. Intake of selected nutrients and biochemical indices of trace and ultratrace mineral status and plasma retinol and α-tocopherol concentrations were evaluated. The means of iron status indices (complete blood count, plasma ferritin, iron, transferrin saturation, total iron binding capacity) and the plasma concentrations of trace and ultratrace minerals (copper, manganese, molybdenum, selenium, zinc) and plasma retinol and α-tocopherol were in the reference ranges. Vitamin A intakes (r = 0.49,p < 0.05) and plasma retinol-binding protein concentrations (r = 0.42,p < 0.05) were positively correlated with plasma retinol concentrations at 3 mo of study. At 6 mo, concentrations of plasma transthyretin (r = 0.72,p < 0.01) and retinolbinding protein (r = 0.48,p < 0.05) were positively correlated with plasma retinol concentrations. At 6 mo, concentrations of plasma transthyretin (r = 0.52,p < 0.05) were positively correlated with retinol-binding protein concentrations. Phenex-1 supports normal mean iron status indices and mean concentrations of trace and ultratrace minerals, retinol, and α-tocopherol when fed in adequate amounts.     

E2A proteins enforce a proliferation checkpoint in developing thymocytes

E2A proteins regulate multiple stages of thymocyte development and suppress T-cell lymphoma. The activity of E2A proteins throughout thymocyte development is modulated by signals emanating from the pre-TCR and TCR. Here we demonstrate that E2A is required for the complete arrest in both differentiation and proliferation observed in thymocytes with defects in proteins that mediate pre-TCR signaling, including LAT, Lck and Fyn. We show that E2A proteins are required to prevent the accumulation of TCRbeta negative cells beyond the pre-TCR checkpoint. E2A-deficient thymocytes also exhibit abnormal cell-cycle progression prior to pre-TCR expression. Furthermore, we demonstrate that E47 can act in concert with Bcl-2 to induce cell-cycle arrest in vitro. These observations indicate that E2A proteins function during early thymocyte development to block cell-cycle progression prior to the expression of TCRbeta. In addition, these data provide further insight into how deficiencies in E2A lead to T lymphoma.     

Complex spatial distribution and dynamics of an abundant Escherichia coli outer membrane protein, LamB

Advanced techniques for observing protein localization in live bacteria show that the distributions are dynamic. For technical reasons, most such techniques have not been applied to outer membrane proteins in Gram-negative bacteria. We have developed two novel live-cell imaging techniques to observe the surface distribution of LamB, an abundant integral outer membrane protein in Escherichia coli responsible for maltose uptake and for attachment of bacteriophage lambda. Using fluorescently labelled bacteriophage lambda tails, we quantitatively described the spatial distribution and dynamic movement of LamB in the outer membrane. LamB accumulated in spiral patterns. The distribution depended on cell length and changed rapidly. The majority of the protein diffused along spirals extending across the cell body. Tracking single particles, we found that there are two populations of LamB--one shows very restricted diffusion and the other shows greater mobility. The presence of two populations recalls the partitioning of eukaryotic membrane proteins between 'mobile' and 'immobile' populations. In this study, we have demonstrated that LamB moves along the bacterial surface and that these movements are restricted by an underlying dynamic spiral pattern.     

Twin seasonality in a rural Catalonian population

The seasonality of twinning in the Spanish populations has not been studied until now. Differences between seasonal distribution of the twin conceptions and those of the single births have been observed in other populations. The aim of this work is to explore the frequency of twinning in a rural population from Catalonia during the nineteenth century, as well as the seasonality patterns characterizing each of the twinning types. Data corresponding to all births recorded at Tortosa (South Catalonia) from 1801 to 1900 have been analyzed in order to study the twinning distribution. The distribution of the moving averages of the monthly rates of twins shows a peak in autumn. Twinning distribution differs from the total births' distribution in Tortosa. This fact is very clear in the case of unlike-sexed twins that have their greater incidence in the last quarter of the year, while the total maternities have their peak in the first one.     

Genetic susceptibility and risk of gastric cancer in a human population of Cauca, Colombia

Gastric cancer (GC) is the main cause of mortality by cancer in Colombia. Glutathione S-transferase (GST) enzymes are involved in the detoxification of many environmental carcinogens. The homozygous deletions of glutathione S-transferase M1 (GSTM1-0) and glutathione S-transferase T1 (GSTT1-0) have been associated with several types of cancer. The risk to develop GC has been associated with environmental factors and Helicobacter pylori infection. The tumor necrosis factor (TNF-alpha) and its levels are increased in patients infected with H. pylori. A G/ A transition in the position -308 of the promoter of the TNF-alpha has been related in several studies to an increased expression of the gene and is associated with susceptibility to GC. The association of these polymorphisms with GC and the interaction with other risk factors (life style) were investigated. Blood samples were obtained from 46 GC patients and 96 controls. The logistic regression model was used to obtain the odds ratio (OR) and their 95% confidence intervals. These statistics established the association between the enzymatic polymorphisms and GC and between other independent factors and GC. The frequency of the TNF-alpha polymorphism in people infected with H. pylori was 18% in the GC population and 7% in the control group. This transition was not significantly associated with H. pylori infection and GC. The frequencies of the deletion polymorphisms for patients and controls were as follows: GSTM1 65.2% and 37.5%; GSTT1 17.4% and 14.6%. These results suggested that the GSTM1 deletion polymorphism was associated with an increased risk of gastric cancer (OR of 5.5; 95%CI, 1.7-17.2). Furthermore, other risk factors such as H. pylori infection (OR 5.58, CI 1.8-17.2), smoking (OR 6.70, CI 2.2-20.3) and alcohol intake (OR 3.27, CI 1.1-9.4) were associated with GC.     

Polyamine uptake in cultured cerebellar granule neurons

In the present study, we have examined the transport of polyamines in cultured cerebellar granule cells. Our results suggest the existence of two different transporters for polyamines in these neurons. Putrescine and spermidine uptake (K ap m = 2.17 and 1.39 microM, respectively), were affected when extracellular sodium was replaced with choline (about 30% inhibition over controls) or sucrose (about 2.5-fold potentiation over controls). By contrast, the substitution of sodium by choline or sucrose did not modify spermine uptake (K ap m = 13.53 microM) in cerebellar granule cells. Accordingly, alteration of membrane potential with ouabain was able to block putrescine (50% inhibition) and spermidine (60% inhibition) uptake but not spermine uptake. These results indicate that putrescine and spermidine transport in cerebellar granule cells is membrane potential dependent, whereas spermine uptake is not modulated by membrane potential.