Impact of reduced insulin-like growth factor-1/insulin signaling on aging in mammals: novel findings

Growth hormone deficiency or resistance resulting from spontaneous or experimentally produced mutations in laboratory mice delay aging and increase lifespan. Alterations in insulin-like growth factor-1 (IGF-1) and insulin signaling emerged as likely mechanisms linking growth hormone and aging, and increased longevity was reported in mice with selective deletion of IGF-1 receptor in all tissues or insulin receptor in fat. Recent studies in mice with reduced IGF-1 levels or deletion of pregnancy-associated plasma protein-A, a protease that cleaves one of the IGF-1 binding proteins, strongly support the role of IGF-1 in the control of longevity. Reports of increased lifespan in mice with deletion of insulin receptor substrate (IRS) 1, reduced expression of IRS2, or selective deletion of IRS2 in the brain specifically implicate the IRS-PI3K-Akt-Foxo signaling pathway (which is shared by IGF-1 and insulin) in the control of aging. These important novel findings also strengthen the evidence for evolutionary conservation of mechanisms regulating lifespan in worms, insects and mammals.     

Dead or gone? Bayesian inference on mortality for the dispersing sex

Estimates of age‐specific mortality are regularly used in ecology, evolution, and conservation research. However, estimating mortality of the dispersing sex, in species where one sex undergoes natal dispersal, is difficult. This is because it is often unclear whether members of the dispersing sex that disappear from monitored areas have died or dispersed. Here, we develop an extension of a multievent model that imputes dispersal state (i.e., died or dispersed) for uncertain records of the dispersing sex as a latent state and estimates age‐specific mortality and dispersal parameters in a Bayesian hierarchical framework. To check the performance of our model, we first conduct a simulation study. We then apply our model to a long‐term data set of African lions. Using these data, we further study how well our model estimates mortality of the dispersing sex by incrementally reducing the level of uncertainty in the records of male lions. We achieve this by taking advantage of an expert's indication on the likely fate of each missing male (i.e., likely died or dispersed). We find that our model produces accurate mortality estimates for simulated data of varying sample sizes and proportions of uncertain male records. From the empirical study, we learned that our model provides similar mortality estimates for different levels of uncertainty in records. However, a sensitivity of the mortality estimates to varying uncertainty is, as can be expected, detectable. We conclude that our model provides a solution to the challenge of estimating mortality of the dispersing sex in species with data deficiency due to natal dispersal. Given the utility of sex‐specific mortality estimates in biological and conservation research, and the virtual ubiquity of sex‐biased dispersal, our model will be useful to a wide variety of applications.     

山东古代居民骨化甲状软骨的观测

本文以山东地区6处考古遗址出土的18例古代居民的骨化甲状软骨为研究材料,结合现代医学和法医学的研究,通过对甲状软骨骨化情况的观察分析以及部分数据测量,发现古代居民中骨化甲状软骨多保存骨板下缘、下结节以及上下角,而且骨化甲状软骨对古代居民性别和年龄的判断有一定指示作用。甲状软骨在骨化程度、进展速度以及骨化机制上存在性别差异,古代居民中男性比女性更容易保存骨化甲状软骨,且男性多见保存联合部中下段,女性并无个体保存联合部。另外在本文的骨化甲状软骨的两项测量数据上,男性明显大于女性。甲状软骨的骨化个体间差异很大,单独使用甲状软骨骨化规律进行年龄判断并不可取,但可作为一种参考依据来辅助判断。值得注意的是,保存有骨化甲状软骨且年龄明确的古代居民皆大于30岁。     

Cognitive differences in dream content between Argentine males and females using quantitative content analysis.

This study asked the question, Are there significant content differences between male and female dream reports obtained in seminars conducted in Argentina? Each of the 100 female and 100 male participants contributed one recent dream report during dream seminars held in Argentina between 1990 and 1998. Dream reports were scored using Hall and Van de Castle's System of Content Analysis. Major findings revealed that Argentine males reported significantly more aggressions per character and a higher percentage of dreamers as the aggressor than reported by females. They also reported more dreams with at least one success than reported by females. In contrast, females scored significantly higher on both the Self-Negativity index and the Negative Emotions index compared to males. Although some findings were similar to past studies using American participants, others were unique to this study and may be attributable to the particular sample used, or may suggest actual underlying cultural patterns of contemporary Argentine men and women. Results are discussed in terms of Hall's continuity hypothesis and Domhoff's cognitive model of dreaming. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A study of Choughs'' vocal repertoire: variability related to individuals, sexes and ages

Summary The calls uttered by Choughs (Pyrrhocorax pyrrhocorax) on Islay (S-W Scotland) were recorded during the breeding season. We analysed the vocal repertoire and the degree of call variation, among and within individuals. Eight structurally different calls were identified in Choughs' vocal repertoire. Significant differences in temporal and frequency variables of calls were found between fledglings and adults, whereas females' and males' calls turned out to differ only in two parameters of the commonest call type (chwee-ow). Despite sex-related differences in this call, partners appeared to utter similar versions of it, which suggests that mate vocal mimicry might occur. A certain degree of individuality, i.e. a greater among than within individuals variability, was found in three call types, but the reverse was found in the commonest call of the species. Accordingly, we hypothesise that this call might promote effective species recognition, whereas the other call types would be involved in individual recognition.

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Das stimmliche Repertoire der Alpenkrähe: individuelle, geschlechtliche und altersabhängige Variabilität

Zusammenfassung Während der Brutzeit 1996 wurde das Rufinventar von Alpenkrähen (Pyrrhocorax pyrrhocorax) auf der Insel Islay (SW Schottland) aufgenommen und hinsichtlich individueller Variation und Unterschieden zwischen verschiedenen Individuen analysiert. Acht grundsätzlich verschiedene Rufe wurden unterschieden. Signifikante Unterschiede bestanden zwischen flüggen Jungvögeln und Altvögeln in der Ruffrequenz und der zeitlichen Abfolge der Rufe. Männchen und Weibchen unterschieden sich dagegen nur geringfügig in dem am häufigsten vorgetragenen Ruf. Ungeachtet dieser geringen sexuellen Unterschiede riefen Paarpartner sehr ähnlich, was als Hinweise auf eine Stimmenmimikrie angesehen wird. In drei Ruftypen fand sich eine gewisse Individualität mit größerer Variablität zwischen verschiedenen als innerhalb eines Rufers, wogegen der häufigste Ruf von allen Individuen sehr ähnlich vorgetragen wurde. Es wird geschlossen, daß dieser Ruf der Arterkennung dient, die anderen dagegen mehr der individuellen Erkennung.

     

Coexistence of the predatory cyclopoids Acanthocyclops robustus (Sars) and Mesocyclops leuckarti (Claus) in a small eutrophic lake

The coexistence of two common species of predatory cyclopoid copepods, Acanthocyclops robustus and Mesocyclops leuckarti, in a small, eutrophic lake was studied. Both species are of similar size, inhabit the same water layers and have similar seasonal occurrence. A. robustus shows faster embryonic and postembryonic development and produces bigger clutches. Ingestion rates of A. robustus are higher than in M. leuckarti, especially with large prey types and low temperatures. Females of A. robustus are heavily preyed upon by fish. This predation pressure leads to extremely skewed sex ratios, which are unfavourable to population growth. A. robustus is therefore, on balance, favoured in productive lakes. Dominance over M. leuckarti is, however, less clear in warmer years.     

Avian growth and development rates and age-specific mortality: the roles of nest predation and adult mortality

Previous studies have shown that avian growth and development covary with juvenile mortality. Juveniles of birds under strong nest predation pressure grow rapidly, have short incubation and nestling periods, and leave the nest at low body mass. Life-history theory predicts that parental investment increases with adult mortality rate. Thus, developmental traits that depend on the parental effort exerted (pre- and postnatal growth rate) should scale positively with adult mortality, in contrast to those that do not have a direct relationship with parental investment (timing of developmental events, e.g. nest leaving). I tested this prediction on a sample of 84 North American songbirds. Nestling growth rate scaled positively and incubation period duration negatively with annual adult mortality rates even when controlled for nest predation and other covariates, including phylogeny. On the contrary, neither the duration of the nestling period nor body mass at fledging showed any relationship. Proximate mechanisms generating the relationship of pre- and postnatal growth rates to adult mortality may include increased feeding, nest attentiveness during incubation and/or allocation of hormones, and deserve further attention.     

Human age reversal: Fact or fiction?

Although chronological age correlates with various age‐related diseases and conditions, it does not adequately reflect an individual''s functional capacity, well‐being, or mortality risk. In contrast, biological age provides information about overall health and indicates how rapidly or slowly a person is aging. Estimates of biological age are thought to be provided by aging clocks, which are computational models (e.g., elastic net) that use a set of inputs (e.g., DNA methylation sites) to make a prediction. In the past decade, aging clock studies have shown that several age‐related diseases, social variables, and mental health conditions associate with an increase in predicted biological age relative to chronological age. This phenomenon of age acceleration is linked to a higher risk of premature mortality. More recent research has demonstrated that predicted biological age is sensitive to specific interventions. Human trials have reported that caloric restriction, a plant‐based diet, lifestyle changes involving exercise, a drug regime including metformin, and vitamin D3 supplementation are all capable of slowing down or reversing an aging clock. Non‐interventional studies have connected high‐quality sleep, physical activity, a healthy diet, and other factors to age deceleration. Specific molecules have been associated with the reduction or reversal of predicted biological age, such as the antihypertensive drug doxazosin or the metabolite alpha‐ketoglutarate. Although rigorous clinical trials are needed to validate these initial findings, existing data suggest that aging clocks are malleable in humans. Additional research is warranted to better understand these computational models and the clinical significance of lowering or reversing their outputs.