Oviposition pattern of the predator Podisus nigrispinus (Heteroptera: Pentatomidae) under different temperatures

The daily reproductive rate of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) fed with Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) larvae was studied at constant temperatures of 20, 23, 25, 28, 30 and 33±0.2°C, relative humidity of 60±10% and photoperiod of L:D 14:10. Daily reproductive rate of P. nigripinus was affected by age of this predator. Each P. nigrispinus female laid 5.3 (20°C) to 19.9 eggs/day (28°C) which developed into 4.3–16.5 nymphs, respectively. Highest daily reproductive rate of P. nigrispinus was recorded at 28 and 30°C for 5–30-day-old females. This predator showed higher daily reproductive rate than its prey A. argillacea at 25°C. It was also able to reproduce at temperatures from 20 to 33°C with maximum daily reproductive rate between 25 and 30°C. These results are important for optimizing mass rearing of P. nigrispinus in the laboratory.     

Secretory structures at syconia and flowers of Ficus enormis (Moraceae): A specialization at ostiolar bracts and the first report of inflorescence colleters

The fig (Ficus L.) infructescence, called syconium, is a receptacle with an apical opening, the ostiole, closed by bracts. The ostiolar bracts produce an exudate, which is rather conspicuous in some species. It has not been histochemically analyzed yet, and the structures responsible for its production are still unknown. Some wild growing species of Ficus from Brazil produce high amounts of this ostiolar exudate. Ficus enormis (Mart. ex Miq.) Miq. grows as trees or shrubs in the Atlantic rainforest. Our goal was to identify the secretory structures present in the inflorescence and, to characterize histochemically the ostiolar tissues and exudates. Syconia samples of F. enormis were processed and stained according to the usual techniques in plant anatomy. The morphological analysis revealed different types of bracts, one type specialized in secretion, another showing transitional characteristics between secretory and non-secreting bracts, and a third one being non-secreting. They are designated as secretory ostiolar bracts, transitional bracts and wall bracts. The floral bracteoles, digital-shaped colleters present in the ostiole, at the syconium axis and at the flower receptacle, were also analyzed. All have similar structure, like finger-shaped secretory trichomes. The colleters present among ostiolar bracts may contribute to production and composition of the ostiole exudate.     

Listeria monocytogenes induces host DNA damage and delays the host cell cycle to promote infection

Listeria monocytogenes (Lm) is a human intracellular pathogen widely used to uncover the mechanisms evolved by pathogens to establish infection. However, its capacity to perturb the host cell cycle was never reported. We show that Lm infection affects the host cell cycle progression, increasing its overall duration but allowing consecutive rounds of division. A complete Lm infectious cycle induces a S-phase delay accompanied by a slower rate of DNA synthesis and increased levels of host DNA strand breaks. Additionally, DNA damage/replication checkpoint responses are triggered in an Lm dose-dependent manner through the phosphorylation of DNA-PK, H2A.X, and CDC25A and independently from ATM/ATR. While host DNA damage induced exogenously favors Lm dissemination, the override of checkpoint pathways limits infection. We propose that host DNA replication disturbed by Lm infection culminates in DNA strand breaks, triggering DNA damage/replication responses, and ensuring a cell cycle delay that favors Lm propagation.     

Diosgenin glucuronides from Solanum lyratum and their cytotoxicity against tumor cell lines

Bioassay-directed fractionation of the cytotoxicity active fraction of the whole plant from Solanum lyratum led to the isolation of a new steroidal saponin, diosgenin 3-O-beta-D-glucopyranosiduronic acid methyl ester (2), as well as four known compounds, diosgenin (1), diosgenin 3-O-beta-D-glucopyranosiduronic acid (3), diosgenin 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosiduronic acid (4), diosgenin 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucuroniduronic acid methyl ester (5). The structures of the isolated compounds were elucidated on the basis of their spectral data and chemical evidences. Compound 1 was isolated for the first time from this plant, and compound 3 was isolated as a new natural product. Cytotoxic activities of the isolated compounds were evaluated and the cytotoxicities of compounds 2-5 reported for the first time.     

A novel and high-throughput approach to assess photosynthetic thermal tolerance of kelp using chlorophyll α fluorometry

Foundation seaweed species are experiencing widespread declines and localized extinctions due to increased instability of sea surface temperature. Characterizing temperature thresholds are useful for predicting patterns of change and identifying species most vulnerable to extremes. Existing methods for characterizing seaweed thermal tolerance produce diverse metrics and are often time-consuming, making comparisons between species and techniques difficult, hindering insight into global patterns of change. Using three kelp species, we adapted a high-throughput method – previously used in terrestrial plant thermal biology – for use on kelps. This method employs temperature-dependent fluorescence (T–F₀) curves under heating or cooling regimes to determine the critical temperature (T_crit) of photosystem II (PSII), i.e., the breakpoint between slow and fast rise fluorescence response to changing temperature, enabling rapid assays of photosynthetic thermal tolerance using a standardized metric. This method enables characterization of T_crit for up to 48 samples per two-hour assay, demonstrating the capacity of T–F₀ curves for high-throughput assays of thermal tolerance. Temperature-dependent fluorescence curves and their derived metric, T_crit, may offer a timely and powerful new method for the field of phycology, enabling characterization and comparison of photosynthetic thermal tolerance of seaweeds across many populations, species, and biomes.     

Elastic fiber assembly in the adult mouse pubic symphysis during pregnancy and postpartum

Impairment of pelvic organ support has been described in mice with genetic modifications of the proteins involved in elastogenesis, such as lysyl oxidase-like 1 (LOXL1) and fibulin 5. During pregnancy, elastic fiber-enriched pelvic tissues are modified to allow safe delivery. In addition, the mouse pubic symphysis is remodeled in a hormone-controlled process that entails the modification of the fibrocartilage into an interpubic ligament (IpL) and the relaxation of this ligament. After first parturition, recovery occurs to ensure pelvic tissue homeostasis. Because ligaments are the main supports of the pelvic organs, this study aimed to evaluate elastogenesis in the IpL during mouse pregnancy and postpartum. Accordingly, virgin, pregnant, and postpartum C57BL/6 mice were studied using light, confocal, and transmission electron microscopy as well as Western blots and real-time PCR. Female mice exhibited the separation of the pubic bones and the formation, relaxation, and postpartum recovery of the IpL. By the time the IpL was formed, the elastic fibers had increased in profile length and diameter, and they consisted of small conglomerates of amorphous material distributed among the bundles of microfibrils. Our analyses also indicated that elastin/tropoelastin, fibrillin 1, LOXL1/Loxl1, and fibulin 5 were spatially and temporally regulated, suggesting that these molecules may contribute to the synthesis of new elastic fibers during IpL development. Overall, this work revealed that adult elastogenesis may be important to assure the elasticity of the pelvic girdle during preparation for parturition and postpartum recovery. This finding may contribute to our understanding of pathological processes involving elastogenesis in the reproductive tract.     

The effect of culture preservation techniques on patulin and citrinin production by Penicillium expansum Link

AIMS: To study the influence of culture preservation methods and culture conditions on the production of the mycotoxins patulin and citrinin by Penicillium expansum. METHODS AND RESULTS: Ten strains of Penicillium expansum were preserved using subculture and maintenance at 4 degrees C, mineral oil, drying on silica gel and freeze-drying. Patulin and citrinin production was assessed on yeast extract sucrose agar (YES) and grape juice agar (GJ), using TLC before and after 0.5, 2-3, 6 and 12 months preservation. Citrinin was detected in all cultures for all preservation techniques on YES. The patulin profiles obtained differed with strain and culture media used. CONCLUSIONS: Citrinin production seems to be a stable character for the tested strains. There is a tendency for patulin detection with time apparently more consistent for silica gel storage and freeze-drying, especially when the strains are grown on GJ. SIGNIFICANCE AND IMPACT OF THE STUDY: Variability in the profiles of the mycotoxins tested seems to be more strain-specific than dependent on the preservation technique used.     

SRFR1 Negatively Regulates Plant NB-LRR Resistance Protein Accumulation to Prevent Autoimmunity

Plant defense responses need to be tightly regulated to prevent auto-immunity, which is detrimental to growth and development. To identify negative regulators of Resistance (R) protein-mediated resistance, we screened for mutants with constitutive defense responses in the npr1-1 background. Map-based cloning revealed that one of the mutant genes encodes a conserved TPR domain-containing protein previously known as SRFR1 (SUPPRESSOR OF rps4-RLD). The constitutive defense responses in the srfr1 mutants in Col-0 background are suppressed by mutations in SNC1, which encodes a TIR-NB-LRR (Toll Interleukin1 Receptor-Nucleotide Binding-Leu-Rich Repeat) R protein. Yeast two-hybrid screens identified SGT1a and SGT1b as interacting proteins of SRFR1. The interactions between SGT1 and SRFR1 were further confirmed by co-immunoprecipitation analysis. In srfr1 mutants, levels of multiple NB-LRR R proteins including SNC1, RPS2 and RPS4 are increased. Increased accumulation of SNC1 is also observed in the sgt1b mutant. Our data suggest that SRFR1 functions together with SGT1 to negatively regulate R protein accumulation, which is required for preventing auto-activation of plant immunity.     

Parasitism in Trialeurodes variabilis (Quaintance) (Hemiptera: Aleyrodidae) by Encarsia hispida De Santis (Hymenoptera: Aphelinidae), in papaya, in Brazil

Infestation of Trialeurodes variabilis (Quaintance) was observed in October 2004, in papaya plants of cultivar Sunrise Solo, under screenhouse conditions, in Cruz das Almas, State of Bahia, Brazil. In infested leaves, around 20% of parasitism on nymphs was verified. Leaves with parasitized nymphs were kept in laboratory until emergence of the parasitoid, identified as Encarsia hispida De Santis. This is the first time that this parasitoid was detected on T. variabilis nymphs in Brazil.