Associations between gastropod shell characteristics and egg production in the hermit crab Pagurus longicarpus

Summary Two populations (salt marsh and seagrass bed) of the hermit crab Pagurus longicarpus were sampled to examine associations between shell characteristics and egg production. Multivariate statistical analyses controlled for crab size and time of year, variables that otherwise could be confounded with shell effects. Although correlations between shell characteristics and reproduction existed in both populations, generalizations could not be made because associations varied within and between populations. Shell species was not associated with a female's reproductive state (i.e., whether or not she was barren when sampled) in either population. In the seagrass population, medium-large and large females occupying severely damaged or fouled shells were half as likely to be reproductive as females occupying other shell conditions. However, there was no association between shell condition and reproductive state for small and small-medium females in the seagrass population or among all females in the salt marsh population. In the seagrass population, small through medium-large reproductive females occupied shells more similar to their predicted shell size, regardless of whether the occupied shell was relatively small or large, than nonreproductive females. In contrast, relative shell sizes of reproductive and nonreproductive females were similar for large females in the seagrass population and all females in the salt marsh population. Clutch sizes were enhanced for females occupying Polinices duplicatus shells or shells larger than their predicted shell size in the seagrass population. Relative shell size also was associated with clutch size in the salt marsh population, but crabs occupying shells similar to their predicted shell size had the largest clutches.     

Thiocyanation of Tubercidin and Its Derivatization to 6-Propyl-and 6-Cyano Derivatives (Nucleosides and Nucleotides. 411.)

Abstract

Thiocyanation of tubercidin with thiocyanogen chloride gave the 5-thiocyanate, which was converted to the 5-methylthio, 5-methylsulfonyl as well as 6-propyl and 6-cyano derivatives. The 6,5′-O-cyclotubercidins were also prepared.     

Does parasitoid state affect host range expression?

The pre-release risk assessment of parasitoids for classical biological control generally involves non-target testing to define the agent’s host range. To ensure that no suitable host species are falsely rejected in these tests, it has been suggested that the physiological and informational state of parasitoids be manipulated to enhance their “motivation to oviposit”. However, the effects of such factors on host acceptance are not consistent across parasitoid species, making it laborious to identify the conditions necessary to maximise host acceptance. Our objective was to determine whether changes in parasitoid state could alter host acceptance behaviour sufficiently to affect host range expression. In addition, we tested the assumption that a state-dependent shift in motivation to oviposit on the target host will translate to a similar change in responsiveness to lower-ranked host species. Three-day-old and 10-day-old females of the candidate classical biological control agent, Diadromus pulchellus, were offered 12 non-target species of varying relatedness to the target pest, Acrolepiopsis assectella, in a series of no-choice and choice oviposition trials. Younger D. pulchellus females had previously demonstrated greater motivation to oviposit in the target pest and were, therefore, predicted to express a broader host range than older females. Parasitoid age had a minor effect on host range expression that was contrary to expectations. Older females more readily attacked one of the non-target species in no-choice tests and inflicted higher mortality in one of the choice tests. Ultimately however, young and old parasitoids still attacked the same four non-target species and their offspring emerged from the same three. There was an interaction between the effects of parasitoid condition and experimental design on responsiveness to low-ranked hosts: increasing non-target density in choice tests significantly altered attack rates by 10-day-old, but not by 3-day-old, parasitoids. The implications of these findings for host specificity testing depend largely on the specific aims of a host range assessment. Parasitoid state influenced the frequency of non-target attack but did not affect which non-target species were attacked.     

用列联表研究纬度和海拔高度对红杉分布的影响

 本文目的在于探讨列联表用于植物地理学研究。通过用列联表研究垂直高度与纬度对红杉(Larix potaninii)分布的影响,找出垂直高度、纬度及其交互作用等的效应,并且找出了红杉的分布中心。由于卡方检验,剩余分析,有序表连带测度,Log-线性模型拟合联合运用,Log-线性模型的运用有一些改进。本文初步证明,列联表用于植物地理学研究是可以成功的。     

Log-linear Models for Polytomous Data

The present study discusses two variants of linear logistic models for polytomous variables for ?unordered”? and for ?ordered”? categories (polydimensional and one-dimensional model). The ML-estimation equations and the possibilities to test the validity of the model are given for both. A test for goodness-of-fit (external validity) and a test for equality of the parameter estimates for split data (interval validity) are suggested. In addition, statistical tests for the significance of individual parameters on the basis of the information matrix and likelihood ratio tests for one or more parameters are described. The presentation is completed by an empirical example from the area of audiology.     

Die energetische Verwertung der Futterstoffe

Abstract

Feeding broiler chicks on graded levels of fluorine (0, 25, 125, 625 and 3125 ppm F) from NaF for 4 weeks (4–7 weeks of age) resulted in various alterations which depended on the level of contamination. The main changes included poor growth and feed conversion, high mortality rate, disorders of bone formation, decreased relative weights of pituitary, adrenal, heart, liver, spleen, lungs, kidneys and gizzard and changes in intestinal dimensions. Also, the biochemical tests revealed other kinds of physiological disfunction mainly in the form of anaemia (low haematocrit, haemoglobin, total protein, albumin and globulin fractions), intoxication (increased methaemoglobin), nephrotic (raised phosphorus and magnesium) and hepatic (elevated lipoproteins and lowering enzymatic activity) disfunctions. The general observations and postmortem examination confirmed also the biochemical findings which revealed the harmful effect of feedborne-fluorine intoxication in broiler chicks.

Die Fütterung von Broilerküken mit abgestuften Fluorniveaus (0, 25, 125, 625 und 3125 mg F/kg Futter) aus NaF über 4 Wochen führte zu verschiedenen Veränderungen, die von der Höhe der Kontamination abhingen. Wesentliche Veränderungen betrafen ein schlechtes Wachstum und einen niedrigen Futteraufwand, eine hohe Sterblichkeitsrate, Unregelmäßigkeiten bei der Knochenbildung, eine verminderte relative Masse von Hypophyse, Nebennieren, Herz, Leber, Milz, Lungen, Nieren und Magen sowie Veränderungen von Länge und Durchmesser der Därme. Darüber hinaus zeigten die biochemischen Untersuchungen physiologische Funktionsstörungen, hauptsächlich in der Form von Anämie (niedrige Werte für Hämatokrit, Hämoglobin, Gesamtprotein sowie Albumin- und Globulin-fraktionen), Vergiftungen (erhöhter Methämoglobinspiegel), Nierendysfunktion (erhöhter Phosphor- und Magnesiumgehalt) und Leberdysfunktion (erhöhter Lipoproteingehalt und verminderte Enzymaktivität). Die allgemeine Beobachtung und die Untersuchung nach der Schlachtung bestätigten ebenfalls die Ergebnisse der biochemischen Untersuchungen, die den negativen Effekt der Fluorvergiftung aufzeigte.     

Models of Chance when Measuring Interrater Agreement with Kappa

Two measures of reliability for nominal scales are compared: Coefficient Kappa and k_n, a modification suggested for agreement matrices with free marginals. It is illustrated that the evaluation of two rater's agreement may come to a contradictory conclusion, depending on whether k or k_n is used. On the basis of the underlying chance models it is concluded that k and k_n cannot be interpreted in the same manner. Specifically when raters disagree, the two measures can be widely discrepant.     

Quasi-stationary and ratio of expectations distributions: A comparative study

Many stochastic systems, including biological applications, use Markov chains in which there is a set of absorbing states. It is then needed to consider analogs of the stationary distribution of an irreducible chain. In this context, quasi-stationary distributions play a fundamental role to describe the long-term behavior of the system. The rationale for using quasi-stationary distribution is well established in the abundant existing literature. The aim of this study is to reformulate the ratio of means approach ( [Darroch and Seneta, 1965] and [Darroch and Seneta, 1967]) which provides a simple alternative. We have a two-fold objective. The first objective is viewing quasi-stationarity and ratio of expectations as two different approaches for understanding the dynamics of the system before absorption. At this point, we remark that the quasi-stationary distribution and a ratio of means distribution may give or not give similar information. In this way, we arrive to the second objective; namely, to investigate the possibility of using the ratio of expectations distribution as an approximation to the quasi-stationary distribution. This second objective is explored by comparing both distributions in some selected scenarios, which are mainly inspired in stochastic epidemic models. Previously, the rate of convergence to the quasi-stationary regime is taking into account in order to make meaningful the comparison.     

Fixed or random? On the reliability of mixed‐effects models for a small number of levels in grouping variables

Biological data are often intrinsically hierarchical (e.g., species from different genera, plants within different mountain regions), which made mixed‐effects models a common analysis tool in ecology and evolution because they can account for the non‐independence. Many questions around their practical applications are solved but one is still debated: Should we treat a grouping variable with a low number of levels as a random or fixed effect? In such situations, the variance estimate of the random effect can be imprecise, but it is unknown if this affects statistical power and type I error rates of the fixed effects of interest. Here, we analyzed the consequences of treating a grouping variable with 2–8 levels as fixed or random effect in correctly specified and alternative models (under‐ or overparametrized models). We calculated type I error rates and statistical power for all‐model specifications and quantified the influences of study design on these quantities. We found no influence of model choice on type I error rate and power on the population‐level effect (slope) for random intercept‐only models. However, with varying intercepts and slopes in the data‐generating process, using a random slope and intercept model, and switching to a fixed‐effects model, in case of a singular fit, avoids overconfidence in the results. Additionally, the number and difference between levels strongly influences power and type I error. We conclude that inferring the correct random‐effect structure is of great importance to obtain correct type I error rates. We encourage to start with a mixed‐effects model independent of the number of levels in the grouping variable and switch to a fixed‐effects model only in case of a singular fit. With these recommendations, we allow for more informative choices about study design and data analysis and make ecological inference with mixed‐effects models more robust for small number of levels.     

Sulfur dioxide,a double-faced molecule in mammals

Sulfur dioxide (SO₂) is a common air pollutant and is detrimental to many organs. Its toxic effects including oxidative damage, deoxyribonucleic acid (DNA) damage and inflammation have been extensively studied. However, recent studies showed that SO₂ can be generated endogenously in mammals. In contrast to the toxic effects of SO₂, protective effects have also been found in mammals. Endogenous SO₂ has antioxidant, anti-inflammatory, anti-hypertension, and anti-atherogenic effects and regulates vascular tone and cardiac function in mammals. SO₂ may have a dual role in regulating physiological and pathophysiological effects in mammals. The biological effects of SO₂ in mammals are reviewed in this study.     

猪——研究人类营养代谢和医药的新宠

建立与人类生理特征较近的动物模型,是开展人类营养和生物医学等各种研究的基础。猪作为实验动物在解剖及生理结构等特点与人类极为相似,具有众多的优势,因而受到越来越多的关注,已应用于营养、生理、病理等多种研究领域。本文介绍了猪作为实验动物模型的生理学特性、国内外研究进展及其趋势,以促进其在营养代谢和医药等方面的进一步研究应用。     

Vergleichende untersuchungen von futterverzehr,leistungsdaten und physiologischen kennwerten zwischen kühen mit hohem und niedrigem milcheiweissgehalt

Aus 12 Fütterungsversuchen wurde durch Auswahl der im Milcheiweißgehalt sich extrem unterscheidenden Kühe jeder Versuchs‐ und Kontrollgruppe eine “Hocheiweiß‐”; und eine “Niedrigeiweißgruppe”; gebildet. Die Differenzen zwischen beiden Gruppen in den geprüften Parametern der Futteraufnahme, des Energieaufwandes, der Lebendmasseentwicklung und der physiologischen Kennwerte waren nur unbedeutend bzw. nicht eindeutig, so daß angenommen werden kann, daß sich Kühe mit hohem und niedrigem Milcheiweißgehalt in den untersuchten Parametern nicht unterscheiden. Als mögliches Unterscheidungsmerkmal deutet sich der Titer an freien Aminosäuren im Blutserum an.     

应用试验设计提高蝮蛇抗栓酶产量的研究

试验设计是研究使试验过程科学化、合理化的一门学科。本文介绍了应用试验设计方法寻找生产蝮蛇抗栓酶的最佳工艺,从而有效地提高了产品产量,并取得明显经济效益