Fattening strategies of wintering great tits support the optimal body mass hypothesis under conditions of extremely low ambient temperature

1.  In a seasonal environment, subcutaneous energy reserves of resident animals often increase in winter and decline again in summer reflecting gradual seasonal changes in their fattening strategies. We studied changes in body reserves of wintering great tits in relation to their dominance status under two contrasting temperature regimes to see whether individuals are capable of optimizing their body mass even under extreme environmental conditions.
2.  We predicted that dominant individuals will carry a lesser amount of body reserves than subordinate great tits under mild conditions and that the body reserves of the same dominant individuals will increase and exceed the amount of reserves of subordinates under conditions of extremely low ambient temperatures, when ambient temperature dropped down to −37 °C.
3.  The results confirmed the predictions showing that dominant great tits responded to the rising risk of starvation under low temperatures by increasing their body reserves and this was done at the expense of their safety.
4.  Removal experiments revealed that lower body reserves of subordinate flock members are due to the increased intraspecific competition for food under low ambient temperatures.
5.  Our results also showed that fattening strategies of great tits may change much quicker than previously considered, reflecting an adaptive role of winter fattening which is sensitive to changes in ambient temperatures.     

Calcineurin inhibition enhances motor neuron survival following injury

The immunosuppressive agents cyclosporin A (CsA) and FK‐506 have previously been shown to exhibit neurotrophic and neuroprotective properties in vivo. Given that significant clinical expertise exists for both drugs, they represent an attractive starting point for treatment of acute neural injuries. One putative mechanism for neuroprotection by these drugs relates to inhibition of calcineurin activity. However each drug–immunophilin complex can potentially influence additional signal transduction pathways. Furthermore, several non‐immunosuppressive immunophilin ligands have been described as possessing neuroprotective properties, suggesting that neuroprotection may be separable from calcineurin inhibition. In the present study, we examined the mechanism of this neuroprotection in facial motor neurons following axotomy‐induced injury. Similar to previous studies in rats, CsA and FK‐506 enhanced motor neuron survival in mice following acute injury. To examine the mechanism responsible for neuroprotection by these agents, pharmacologic inhibitors of several potential alternate signalling pathways (17‐(allylamino)‐17‐demethoxygeldanamycin, rapamycin, cypermethrin) were evaluated with respect to neuroprotection. Of these, only cypermethrin, a direct calcineurin inhibitor not previously associated with neuronal survival properties, was observed to significantly enhance motor neuron survival following injury. The results demonstrate for the first time that direct inhibition of calcineurin is neuroprotective in vivo. These data support a model in which calcineurin inhibition promotes neuronal survival, distinct from effects upon neurite outgrowth.     

Lateral reorganization of plasma membrane is involved in the yeast resistance to severe dehydration

In this study, we investigated the kinetic and the magnitude of dehydrations on yeast plasma membrane (PM) modifications because this parameter is crucial to cell survival. Functional (permeability) and structural (morphology, ultrastructure, and distribution of the protein Sur7-GFP contained in sterol-rich membrane microdomains) PM modifications were investigated by confocal and electron microscopy after progressive (non-lethal) and rapid (lethal) hyperosmotic perturbations. Rapid cell dehydration induced the formation of many PM invaginations followed by membrane internalization of low sterol content PM regions with time. Permeabilization of the plasma membrane occurred during the rehydration stage because of inadequacies in the membrane surface and led to cell death. Progressive dehydration conducted to the formation of some big PM pleats without membrane internalization. It also led to the modification of the distribution of the Sur7-GFP microdomains, suggesting that a lateral rearrangement of membrane components occurred. This event is a function of time and is involved in the particular deformations of the PM during a progressive perturbation. The maintenance of the repartition of the microdomains during rapid perturbations consolidates this assumption. These findings highlight that the perturbation kinetic influences the evolution of the PM organization and indicate the crucial role of PM lateral reorganization in cell survival to hydric perturbations.     

健脾益肾通络方对MPTP诱导的帕金森病小鼠肠道菌群与短链脂肪酸的调节作用

探讨健脾益肾通络方（JYTR）对1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP）诱导的帕金森病小鼠肠道菌群组成和短链脂肪酸的影响。

将成年雄性C57BL/6小鼠随机分成3组：空白组、MPTP组、MPTP+JYTR组,每组15只。采用爬杆、悬挂、横梁实验评估运动情况。采用免疫荧光法检测纹状体酪氨酸羟化酶（TH）的表达。采用蛋白印迹法检测纹状体和结肠中α-突触核蛋白（α-syn）的表达。采用16S核糖体RNA（16S rRNA）基因测序评估肠道菌群的变化。采用气相色谱质谱法（GC-MS）分析小鼠粪便短链脂肪酸的水平。最后对差异菌群和短链脂肪酸进行相关性分析。

与MPTP组相比,MPTP+JYTR组小鼠悬挂评分增加（P=0.040）,爬杆时间和横梁行走时间显著缩短（P=0.042、P＜0.001）;纹状体TH表达显著增加（P=0.045）,纹状体、结肠中α-syn表达显著减少（P=0.011、P=0.037）;肠道菌群alpha多样性、beta多样性显著改变;门水平方面拟杆菌门丰度增加（P=0.003）,厚壁菌门、疣微菌门丰度均显著减少（P=0.001、P=0.011）;科水平方面毛螺菌科丰度显著升高（P=0.001）,嗜黏蛋白阿克曼菌科、丹毒丝菌科丰度均显著降低（P=0.008、P=0.004）;短链脂肪酸中乙酸、丙酸水平均显著增加（P=0.014、P=0.010）。相关性分析显示爬杆时间、悬挂评分、横梁时间均与肠道菌群、短链脂肪酸存在相关性。

JYTR可以通过调节肠道菌群失调和改善短链脂肪酸水平起到治疗帕金森病的作用。

     

Fitness costs and benefits of antipredator behavior mediated by chemotactile cues in the wolf spider Pardosa milvina (Araneae: Lycosidae)

Animals may exhibit a variety of defensive behaviors in thepresence of indirect predator cues. Such behavior offers immediatefitness benefits but may also incur substantial foraging andreproductive costs. We measured shifts in space use (verticalclimbing) by the wolf spider Pardosa milvina induced by chemotactilecues (silk and excreta) from a co-occurring predatory wolfspider Hogna helluo. We then measured foraging and reproductive costs, as well as survival benefits, of this behavior. For 2weeks, we maintained mated adult female Pardosa in plasticcontainers with one of three treated peat moss substrates:a container previously occupied by a conspecific for 3 days,a container previously occupied by an adult Hogna for 3 days,and a container devoid of either cue (control). We measuredprey capture efficiency, body condition, egg sac production,egg sac weight, and egg number for individuals in each treatment.We also counted the number of Pardosa that survived and exhibitedclimbing behavior in the presence of a live Hogna with andwithout silk and excreta cues. Pardosa climbed container wallssignificantly more often in the presence of Hogna silk andexcreta relative to other treatments. Pardosa exposed to Hognacues coupled with live Hogna survived significantly longerthan spiders that had no predator cues available. Pardosa placedin containers with Hogna cues, but no Hogna, lost weight morequickly, ate fewer prey, were in poorer body condition, producedlighter egg sacs, and produced fewer eggs than spiders in controlor conspecific treatments.     

A new semiparametric estimation method for accelerated hazard model

The accelerated hazard model has been proposed for more than a decade. However, its application is still very limited, partly due to the complexity of the existing semiparametric estimation method. We propose a new semiparametric estimation method based on a kernel-smoothed approximation to the limit of a profile likelihood function of the model. The method leads to smooth estimating equations and is easy to use. The estimates from the method are proved to be consistent and asymptotically normal. Our numerical study shows that the new method is more efficient than the existing method. The proposed method is employed to reanalyze the data from a brain tumor treatment study.     

Interactions of Salmonella enterica with lettuce leaves

Aims:  To investigate the interactions of Salmonella enterica with abiotic and plant surfaces and their effect on the tolerance of the pathogen to various stressors.
Methods and Results:  Salmonella strains were tested for their ability to form biofilm in various growth media using a polystyrene plate model. Strong biofilm producers were found to attach better to intact Romaine lettuce leaf tissue compared to weak producers. Confocal microscopy and viable count studies revealed preferential attachment of Salmonella to cut-regions of the leaf after 2 h at 25°C, but not for 18 h at 4°C. Storage of intact lettuce pieces contaminated with Salmonella for 9 days at 4°C resulted only in small changes in population size. Exposure of lettuce-associated Salmonella cells to acidic conditions (pH 3·0) revealed increased tolerance of the attached vs planktonic bacteria.
Conclusions:  Biofilm formation on polystyrene may provide a suitable model to predict the initial interaction of Salmonella with cut Romaine lettuce leaves. Association of the pathogen with lettuce leaves facilitates its persistence during storage and enhances its acid tolerance.
Significance and Impact of the Study:  Understanding the interactions between foodborne pathogens and lettuce might be useful in developing new approaches to prevent fresh produce-associated outbreaks.     

Demographic effects of a megafire on a declining prairie grouse in the mixed‐grass prairie

Recent studies have documented benefits of small, prescribed fire and wildfire for grassland‐dependent wildlife, such as lesser prairie‐chickens (Tympanuchus pallidicintus), but wildlife demographic response to the scale and intensity of megafire (wildfire >40,000 ha) in modern, fragmented grasslands remains unknown. Limited available grassland habitat makes it imperative to understand if increasing frequency of megafires could further reduce already declining lesser prairie‐chicken populations, or if historical evolutionary interactions with fire make lesser prairie‐chickens resilient. To evaluate lesser prairie‐chicken demographic response to megafires, we compared lek counts, nest density, and survival rates of adults, nests, and chicks before (2014–2016) and after (2018–2020) a 2017 megafire in the mixed‐grass prairie of Kansas, USA (Starbuck fire ~254,000 ha). There was a 67% decline in attending males on leks post‐fire and a 57% decline in occupied leks post‐fire. Despite population declines as indicated by lek counts, adult female breeding season survival (S^) was similar pre‐ (S^ = 0.65 ± 0.08 [SE]) and post‐fire (0.61 ± 0.08), as was chick survival (pre‐fire: 0.23 ± 0.07; post‐fire: 0.27 ± 0.11). Nest survival appeared lower post‐fire (pre‐fire: 0.38 ± 0.06; post‐fire: 0.20 ± 0.06), but did not differ at the 95% confidence interval. Nest density of marked females declined 73% in areas burned by megafire. Although lesser prairie‐chickens persisted in the study area and we documented minimal effects on most demographic rates, reduced lesser prairie‐chicken abundance and reproductive output suggests full recovery may take >3 years. Increased propensity for megafire resulting from suppression of smaller fires, compounded by climate change and woody encroachment, may impose a short‐term (3–5 year) threat to already declining lesser prairie‐chicken populations.     

Flowers and fruits prolong survival of drosophila pupal parasitoids

Adult parasitoids often feed on sugar sources for survival and to fuel energy. Therefore, the provision of sugar sources, such as nectar from flowers, can enhance biological control. We assessed whether Pachycrepoideus vindemmiae and Trichopria drosophilae, two pupal parasitoids of Drosophila spp., can profit from different sugar sources. In a laboratory experiment, we offered honey, cornflower and buckwheat flowers, crushed and Drosophila suzukii-infested blueberries as well as hosts together with honey. In both parasitoid species, all food sources significantly prolonged the lifespan of females compared to the control. The flowers prolonged the lifespan in both species threefold or fourfold, in P. vindemmiae from a mean of 6 to 28 days, in T. drosophilae from 13 to 49 days. Infested and damaged blueberries also enhanced mean survival in both species. When fed honey, the presence of hosts slightly decreased lifespan in P. vindemmiae and strongly decreased it in T. drosophilae. Our results suggest that the parasitoids can utilize the fruits they encounter during host search. Flowers could enhance their biological control function even further, as long as they do not benefit the pest.