Survival of nisin activity in intestinal environment

The sensitivity of nisin to proteolytical breakdown in intestinal environment was studied in an ex vivo model using jejunal chyme from fistulated dogs. Sixty six percentage of the added nisin retained induction activity after 30 min incubation in jejunal chyme, indicating that nisin has potential to be used as an inducing agent in in situ delivery systems of bioactive peptides and proteins by genetically modified bacteria in the intestine.     

Clutch size and the costs of incubation in the house wren

Trade-offs in the allocation of finite resources among differentstages of a breeding attempt as well as between different reproductiveevents should shape the evolution of life-history traits. Toinvestigate the effects of incubation effort on within-broodand between-brood trade-offs in house wrens (Troglodytes aedon),we manipulated the clutch size that females incubated. We isolatedeffects of incubation by reversing the manipulation at hatchingto allow all parents to provision their natural brood sizes.Females that incubated enlarged clutches had longer incubationperiods than control females, both early and late in the season,suggesting that the experimental treatment increased incubationeffort. Contrary to predictions, however, increased incubationeffort did not adversely affect the allocation of effort tonestling provisioning. Rather, in the early season, but notin the late season, females that incubated enlarged clutchesappeared to allocate more effort to nestling provisioning, producingheavier and larger fledglings than control females. Althoughfemales with enlarged early-season clutches consequently lostmore mass than control females, this was likely an adaptiveresponse to reduce wing loading in anticipation of high provisioningdemands. There were no treatment-related differences in fledglingmass or size, or in female mass loss, in the late season. Thus,elevated incubation demands negatively affected a fitness-relatedtrait (duration of incubation) that may constrain clutch sizebut not the allocation of resources to subsequent stages ofthe same breeding event or to subsequent breeding events. Wesuggest that environmental conditions may mediate clutch-sizeeffects on trade-offs in allocation of resources between incubationand nestling provisioning.     

Regulation of TBK1 activity by Optineurin contributes to cell cycle-dependent expression of the interferon pathway

The innate immune system has evolved to detect and neutralize viral invasions. Triggering of this defense mechanism relies on the production and secretion of soluble factors that stimulate intracellular antiviral defense mechanisms. The Tank Binding Kinase 1 (TBK1) is a serine/threonine kinase in the innate immune signaling pathways including the antiviral response and the host defense against cytosolic infection by bacteries. Given the critical roles of TBK1, important regulatory mechanisms are required to regulate its activity. Among these, Optineurin (Optn) was shown to negatively regulate the interferon response, in addition to its important role in membrane trafficking, protein secretion, autophagy and cell division. As Optn does not carry any enzymatic activity, its functions depend on its precise subcellular localization and its interaction with other proteins, especially with components of the innate immune pathway. This review highlights advances in our understanding of Optn mechanisms of action with focus on the relationships between Optn and TBK1 and their implication in host defense against pathogens. Specifically, how the antiviral immune system is controlled during the cell cycle by the Optn/TBK1 axis and the physiological consequences of this regulatory mechanism are described. This review may serve to a better understanding of the relationships between the different functions of Optn, including those related to immune responses and its associated pathologies such as primary open-angle glaucoma, amyotrophic lateral sclerosis and Paget’s disease of bone.     

Effects of food type, feeding frequency, and temperature on juvenile survival and growth of Marisa cornuarietis (Mollusca: Gastropoda)

Abstract. The present experiments are part of a larger study designed to investigate the influence of husbandry parameters on the life history of the ramshorn snail, Marisa cornuarietis, in order to identify suitable husbandry conditions for maintaining multi‐generation populations in the laboratory for use in ecotoxicological testing. In this paper we focus on the effects of a combination of food types and feeding frequencies (i.e., the frequency with which the snails were offered food) on juvenile growth and survival at different temperatures. Offspring produced in the laboratory by wild specimens of M. cornuarietis, from Puerto Rico, were used to test the effects of three types of food (lettuce, alginate with fish food, alginate with snail mix) fed at three frequencies (given ad libitum on 4/4, 2/4, or 1/4 d) on juvenile survival and growth. The 4‐d feeding regimens were repeated four times, giving a total of 16 d for the experiments. The experiments were conducted at two temperatures (22° and 25°C) under a 12 h light:12 h dark photoperiod. Juvenile growth rates increased with increasing feeding frequency for all food types. The most rapid growth rates occurred in the high‐frequency lettuce treatments and the slowest growth rates in the low‐frequency lettuce and alginate with snail mix treatments. Juvenile snails grew faster at 25° than at 22°C, and mortality was about twice as high at the lower temperature. Growth rates were used to provide a rough estimate of time to maturity, which was determined to take about twice as long at 22° than at 25°C. The results showed that lettuce is the best food if supplied in abundance, but effects on growth are very dependent on feeding frequency and temperature. We conclude that 25°C is a more appropriate temperature for maintaining populations than 22°C, that lettuce provides a suitable food source, and that food should be supplied continuously for husbandry and toxicity testing of populations of M. cornuarietis.     

Transfer of nitrogen from a tropical legume tree to an associated fodder grass via root exudation and common mycelial networks

Symbiotic dinitrogen fixation by legume trees represents a substantial N input in agroforestry systems, which may benefit the associated crops. Applying ¹⁵N labelling, we studied N transfer via common mycelial networks (CMN) and root exudation from the legume tree Gliricidia sepium to the associated fodder grass Dichantium aristatum . The plants were grown in greenhouse in shared pots in full interaction (treatment FI) or with their root systems separated with a fine mesh that allowed N transfer via CMN only (treatment MY). Tree root exudation was measured separately with hydroponics. Nitrogen transfer estimates were based on the isotopic signature of N ( δ ¹⁵N) transferred from the donor. We obtained a range for estimates by calculating transfer with δ ¹⁵N of tree roots and exudates. Nitrogen transfer was 3.7–14.0 and 0.7–2.5% of grass total N in treatments FI and MY, respectively. Root δ ¹⁵N gave the lower and exudate δ ¹⁵N the higher estimates. Transfer in FI probably occurred mainly via root exudation. Transfer in MY correlated negatively with grass root N concentration, implying that it was driven by source-sink relationships between the plants. The range of transfer estimates, depending on source δ ¹⁵N applied, indicates the need of understanding the transfer mechanisms as a basis for reliable estimates.     

Changes in biochemical composition of vacuoles isolated from Acer pseudoplatanus L. during cell culture

Vacuoles were isolated from Acer pseudoplatanus cell suspension culture using a one-step procedure involving the lysis of the protoplast plasmalemma through a gradient of Ficoll containing DEAE-Dextran. The vacuole suspensions were slightly contaminated by other organelles (less than 5%) and the isolated vacuoles readily accumulated neutral red. Since α-mannosidase was located exclusively in the vacuoles it was used as a convenient marker. It was shown that the number of vacuoles per protoplast decreased as the cell aged. Studies on the biochemical composition of the isolated vacuoles indicated that amino acids, organic acids and protein contents varied with the cell culture cycle, emphasizing the dynamic status of the vacuolar system in cell suspension cultures of Acer pseudoplatanus.     

Autotomy-induced life history plasticity in band-legged ground cricket Dianemobius nigrofasciatus

Crickets can autotomize their limbs when attacked by predators. This enables them to escape death, but imposes a short-term cost on their escape speed and a long-term cost on their future mating ability. Therefore, adaptive response compensated for the cost of autotomy might be advantageous for autotomized individuals. In the present study, we examined whether autotomy induced life history plasticities compensating for the future cost in the band-legged ground cricket Dianemobius nigrofasciatus . Life history traits of D. nigrofasciatus were compared between autotomized and intact individuals. The developmental time and head width of the individuals that were autotomized as fourth instar nymphs were significantly shorter and smaller, respectively, than those of intact individuals. However, the adult longevity, number of eggs laid and oviposition schedule did not vary between autotomized and intact individuals. In addition, there was no difference between individuals autotomized at the fourth instar and adult stages in these three traits. Early maturation in the autotomized individuals might be advantageous through reducing the risk of predation owing to the shorter period in nymphal stages. The cost of small body size in the autotomized females might not be so great because of no significant difference in fecundity between autotomized and intact individuals. However, the cost of small body size was unclear in the autotomized males because in general larger males were preferred by females. These results indicated autotomy-induced life history that might reduce the cost of autotomy.     

Anaerobic growth defects resulting from gene fusions affecting succinyl-CoA synthetase in Escherichia coli K12

Summary Insertion of the fusion-generating phage Mud1 (Ap, lacZ) yielded two similar isolates, DC511 and DC512, which were unable to grow aerobically on acetate or alphaketoglutarate but which could use succinate, malate, fumarate, glycerol, and various sugars. These mutants were unable to grow anaerobically on most sugars unless provided with methionine, lysine, and delta-aminolevulinic acid, all of which require succinyl-CoA for their synthesis. The insertions of both mutants mapped at 17 min, in the suc operon. Enzyme assays indicated a lack of succinyl-CoA synthetase; however, full activity of the alpha-ketoglutarate dehydrogenase was retained. Beta-galactosidase expression by strains containing these gene fusions was reduced under anaerobic conditions. In aerobically grown cultures, both fusions were induced about fivefold in the presence of acetate. This type of regulation would be expected of a Krebs cycle enzyme.     

Larvaler «Triähanismus» Und die Evolution alternativer Entwicklungszyklen bei einem saprobionten Nematoden: Rhabditis (Pelodera) orbitalis (Nematoda) als Larvalparasit im Auge von Mäusen1

Larval triphenism and the evolution of alternative life-cycles in a microbotrophic nematode: Rhabditis (P.) orbitalis – a larval parasite in the eye orbits of murid rodents Along with the normal third stage larva and the resistant dauerlarva, Rh. orbitalis posesses an infective larva, which is an obligate parasite in the eye orbits of mice and voles. Dauerlarvae as well as infective larvae develop from a common pre-stage («girdle-larva»), determined by the quality of food stored in the intestinal cells. – Dauerlarvae may tolerate desiccation (at room-temperature and -humidity) up to 4 weeks. If stored in tap water (at 6°C), they will survive for some month being able to restore development. – Infective larvae never survive desiccation but can also be stored in tap water at low temperatures. Food uptake from the lachrymal fluid of a host is needed prior to restoring development. The phenomenon involved is referred to as a necessary adaptation to the ecological conditions in the rodents' nests. It is also pointed out to the different strategies of other parasitic nematode species.     

Is there a trade‐off between horn growth and survival in adult female chamois?

Life‐history theory predicts trade‐offs in energy allocation between different life‐history traits when resources are limited, i.e. certain traits should be negatively correlated. However, individuals differ in their ability to acquire resources, which can lead to positive correlations between traits at the population level. Here, we investigated the consequences of the allocation in horn growth and body mass on survival in a bovid (Rupicapra rupicapra) with capture‐mark re‐sighting data on 161 females. In female ungulates, body mass often covaries positively with demographic performance and the few studies on horn size suggest that this trait could be a signal of individual quality. Thus, we expected to measure positive correlations between the allocation in these traits and female survival. However, body mass was not correlated to female survival and there was only a negative, though marginal, effect of horn growth. Hence, it seems that the allocation in growth is not an indicator of female quality. Future studies could investigate the importance of growth on female reproduction to evaluate its effect on lifetime reproductive success. Moreover, it is important to confirm in other populations our result that suggests a cost of the allocation in horn growth to better understand the presence of horns in female bovids. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 516–521.