Opportunistic foraging strategy of rainbow lizards at a seaside resort in Togo

Rainbow lizards (Agama agama) are common in suburban areas throughout Africa, and have an opportunistic foraging strategy, with arthropods being the main prey source. In a coastal resort in southern Togo, West Africa, several individuals in a population were observed while feeding regularly upon non-natural human-made food (pizza) and showing a clear preference for a given type of food versus others that were offered (‘four cheeses’ being the preferred one). The fact that all monitored individuals fed upon a same type of pizza suggests that they may have some chemical cues attracting them.     

Shelter selection in the kissing bugs Triatoma infestans and Rhodnius prolixus: Intra- and inter-specific interactions and quality evaluation

Triatomines display most of their activities during the night. Before sunrise, they search, select and occupy adequate shelters to stay during the photophase, avoiding exposure to diurnal predators. In this work, we first explored the interactions between individuals of the same or different species in the shelter selection process of Triatoma infestans (Klug 1834) and Rhodnius prolixus (Stål 1859). When two groups of insects (either of different nutritional status, nymphal instar or species) were released together over an experimental arena containing two identical shelters, all nymphs were distributed randomly, suggesting the absence of intra- and inters-pecific interactions. Secondly, we analysed their preferences for particular features of shelters by releasing one group of insects (either T. infestans or R. prolixus) over an arena containing two different refuges. Nymphs exhibited preferences for darker shelters with a vertical orientation of its substrate and elevated from the ground, highlighting the importance of such features in a shelter selection context. We conclude that these species disregard the presence of other individuals but evaluate certain characteristics of the shelters to choose them. This information may contribute to understanding the colonization/recolonization dynamic processes of these Chagas disease vectors.     

Natural lignin modulators improve bagasse saccharification of sugarcane and energy cane in field trials

The burgeoning cellulosic ethanol industry necessitates advancements in enzymatic saccharification, effective pretreatments for lignin removal, and the cultivation of crops more amenable to saccharification. Studies have demonstrated that natural inhibitors of lignin biosynthesis can enhance the saccharification of lignocellulose, even in tissues generated several months post-treatment. In this study, we applied daidzin (a competitive inhibitor of coniferaldehyde dehydrogenase), piperonylic acid (a quasi-irreversible inhibitor of cinnamate 4-hydroxylase), and methylenedioxy cinnamic acid (a competitive inhibitor of 4-coenzyme A ligase) to 60-day-old crops of two conventional Brazilian sugarcane cultivars and two energy cane clones, bred specifically for enhanced biomass production. The resultant biomasses were evaluated for lignin content and enzymatic saccharification efficiency without additional lignin-removal pretreatments. The treatments amplified the production of fermentable sugars in both the sugarcane cultivars and energy cane clones. The most successful results softened the most recalcitrant lignocellulose to the level of the least recalcitrant of the biomasses tested. Interestingly, the softest material became even more susceptible to saccharification.     

EVIDENCE OF DIFFERENCES IN THE DESOXYRIBONUCLEOPROTEIN COMPLEX OF RAPIDLY PROLIFERATING AND NON-DIVIDING CELLS

1. Quantitative cytophotometric analysis of the interphase cells of a rapidly proliferating differentiated tissue such as liver of new born rat, indicates that these cells can be separated into two groups on the basis of their staining characteristics after methanol fixation. 2. These groups are thought to correspond to two stages of interphase. The first, called "autosynthetic interphase," comprises cells which are duplicating chromosomal material in preparation for mitosis, and shows parallel increases in the methyl green and Feulgen staining of DNA and the fast green staining of histone from the diploid (2 C) to double these values (4 C). 3. The second group is designated the "heterosynthetic interphase," during which the cell ceases proliferating and functions in a manner commensurate with its state of differentiation. In this stage Feulgen staining indicates the diploid chromosomal complement, but there is a decreased capacity of the DNA to bind methyl green and of the histone to bind fast green. 4. The difference between the methyl green binding of the heterosynthetic and autosynthetic 2 C cells is due to the presence of a protein in the former which presumably inhibits staining by competing with the dye for binding sites on the DNA. The effect of this inhibition can be removed by extracting the protein, or by blocking the protein basic groups. 5. The decreased fast green staining of histone in the heterosynthetic cells can be minimized by prolonged fixation with formaldehyde. It is thought to stem either from a similar type of inhibition, or from an increased susceptibility of the histone to loss from the cell during this stage. 6. While histone inhibits methyl green staining of DNA in all cells, the differences between the staining properties of the autosynthetic and heterosynthetic interphase cells are believed to be due to another protein, whose properties appear similar to those of the chromosomal "residual protein." It is concluded that a complex of DNA and residual protein existing during the heterosynthetic interphase is dissociated during the autosynthetic interphase.     

A biphasic model of limb venous compliance: a comparison with linear and exponential models.

Compliance is not linear within the physiological range of pressures, and linear modeling may not describe venous physiology adequately. Forearm and calf venous compliance were assessed in nine subjects. Venous compliance was modeled by using a biphasic model with high- and low-pressure linear phases separated by a breakpoint. This model was compared with a linear model and several exponential models. The biphasic, linear, and two-parameter exponential models best represented the data. The mean coefficient of determination for the biphasic model was greater than for the linear and exponential models in the calf (biphasic 0.94 +/- 0.04, exponential 0.81 +/- 0.16, P = not significant; and linear 0.54 +/- 0.05, P < 0.05) and forearm (biphasic 0.83 +/- 0.17, exponential 0.79 +/- 0.15, P = not significant; and linear 0.51 +/- 0.06, P < 0.05). The breakpoint pressure in the biphasic model was higher in the calf than the forearm, 34.4 +/- 3.9 vs. 29.1 +/- 4.5 mmHg, P < 0.05. A biphasic model can describe limb venous compliance and delineate differences in venous physiology at high and low pressures. The steep low-pressure phase of the compliance curve extends to higher pressures in the calf than in the forearm, thereby enlarging the range of pressures over which hemodynamic regulation by the calf venous circulation occurs.     

Escherichia coli Heat Shock Protein DnaK: Production and Consequences in Terms of Monitoring Cooking

Through use of commercially available DnaK proteins and anti-DnaK monoclonal antibodies, a competitive enzyme-linked immunosorbent assay was developed to quantify this heat shock protein in Escherichia coli ATCC 25922 subjected to various heating regimens. For a given process lethality (F₇₀¹⁰ of 1, 3, and 5 min), the intracellular concentration of DnaK in E. coli varied with the heating temperature (50 or 55°C). In fact, the highest DnaK concentrations were found after treatments at the lower temperature (50°C) applied for a longer time. Residual DnaK after heating was found to be necessary for cell recovery, and additional DnaK was produced during the recovery process. Overall, higher intracellular concentrations of DnaK tended to enhance cell resistance to a subsequent lethal stress. Indeed, E. coli cells that had undergone a sublethal heat shock (105 min at 55°C, F₇₀¹⁰ = 3 min) accompanied by a 12-h recovery (containing 76,786 ± 25,230 molecules/cell) resisted better than exponentially growing cells (38,500 ± 6,056 molecules/cell) when later heated to 60°C for 50 min (F₇₀¹⁰ = 5 min). Results reported here suggest that using stress protein to determine cell adaptation and survival, rather than cell counts alone, may lead to more efficient heat treatment.