Relative Contributions of Urine and Anal-Sac Secretions in Scent Marks of Large Felids

SYNOPSIS. A hypothesis generated from field observations oflions and tigers was tested in a zoo setting. The presence ofa whitish material in urine marks, detected by visual inspection,led to the surmise that analsac secretions were expelled alongwith urine. This hypothesis was evaluated by labelling anal-sacsecretions of various felids with an inert dye. The animalswere monitored thereafter for signs of dye in urine-marks, onfeces or in their enclosures. The failure to find anal-sac secretionsin urine or on feces led to a search for an alternate explanationfor the whitish material. A likely answer was found in the confirmationof considerable lipid in the bladder urine of lions and tigers,which separates to form a visible, whitish layer. Relative levelsof urinary lipid reflect general condition of an animal as theycorrelate with kidney fat reserves (Hewer et al., 1948), sothe amount of lipid in a scent mark could serve as an indicatorof condition. Furthermore, because lipid retards the releaseof volatile compounds (Regnier and Goodwin, 1976), lipid ina scent mark will extend release time of a pheromonal message.     

Canid Reproductive Biology: an Integration of Proximate Mechanisms and Ultimate Causes

SYNOPSIS. The canid reproductive system includes many featuresthat are unusual or even unique among mammals. Focusing on graywolves, for example, these include monogamy, monestrum withexceptionally long proestrous and diestrous phases, a copulatorylock or tie, incorporation of adult young into the social group,behavioral suppression of mating in these subordinate young,obligate pseudopregnancy in subordinate females, and alloparentalcare. These features can be analyzed on the levels of both proximateand ultimate causation by considering them in the context ofthe reproductive system as a whole. First, when assessing possibleproximate mechanisms, monestrum appears to be pivotal. It isprobably accomplished by the extremely long luteal or diestrousphase, which is followed by a seasonal peak in prolactin. Twosequellae of the extended diestrus (or pseudopregnancy) in non-pregnantsubordinate females are to 1) suppress any subsequent cycles,and 2) hormonally prime them to behave maternally. The prolactinpeak in all adult pack members, coincident with the birth ofpups, also may stimulate parental behavior. The risk of monestrum(limited chance for conception) appears to be reduced by therelatively long proestrous and estrous periods, as well as bymonogamy. The adaptive value, or ultimate cause, of this reproductivesystem is most obvious for the more social canid species, suchas the gray wolf. That is, advantages to sociality, such ascooperative hunting, may have driven development of the anomaliesof the reproductive system.     

贝壳砂改良土壤中反硝化细菌的分析

【目的】通过对一处经过长期使用贝壳砂进行改良的土壤中的反硝化细菌的多样性和细菌分离分析,研究该土壤中反硝化细菌的组成特征。【方法】采用454焦磷酸测序的方法分析了土壤样品中微生物群落的组成,选用Giltay培养基培养、鉴定从土壤中挑选的分离物的反硝化能力,并对具有反硝化能力的微生物进行了16S rRNA基因鉴定。【结果】该土壤样品中占据优势地位的为Proteobacteria、Acidobacteria、Bacteroidetes、Chloroflexi等门的微生物,属的水平上则有近70%尚未确立分类地位。所分离的细菌中,共得到12株厌氧条件下具有较高硝酸盐去除效率的微生物,分属Pseudomonas、Aeromonas、Serratia和Acinetobacter,均为γ变形菌纲的微生物。【结论】该土壤中具有较高的微生物多样性,包括很多未知类型的微生物和众多类型的反硝化细菌;分离到了11株具有反硝化能力的菌株,可用于该土壤的反硝化过程的进一步研究。     

Intestinal Mucus Protects Giardia lamblia from Killing by Human Milk1

We have previously shown that nonimmune human milk kills Giardia lamblia trophozoites in vitro. Killing requires a bile salt and the activity of the milk bile salt-stimulated lipase. We now show that human small-intestinal mucus protects trophozoites from killing by milk. Parasite survival increased with mucus concentration, but protection was overcome during longer incubation times or with greater milk concentrations. Trophozoites preincubated with mucus and then washed were not protected. Protective activity was associated with non-mucin CsCl density gradient fractions. Moreover, it was heat-stable, non-dialyzable, and non-lipid. Whereas whole mucus inhibited milk lipolytic activity, protective mucus fractions did not inhibit the enzyme. Furthermore, mucus partially protected G. lamblia trophozoites against the toxicity of oleic acid, a fatty acid which is released from milk triglycerides by lipase. These studies show that mucus protects G. lamblia both by inhibiting lipase activity and by decreasing the toxicity of products of lipolysis. The ability of mucus to protect G. lamblia from toxic lipolytic products may help to promote intestinal colonization by this parasite.     

Lag between Incorporation of Proline into Protocollagen and Synthesis of Hydroxyproline during Collagen Biosynthesis <Emphasis Type="Italic">in vitro</Emphasis> and <Emphasis Type="Italic">in vivo</Emphasis>

THE hydroxyproline and hydroxylysine in collagen are synthesized by hydroxylation of proline and lysine after these amino-acids have been incorporated into peptide linkages (for review see ref. 1). Experiments with embryonic cartilage in vitro in which the hydroxylases were intermittently inhibited demonstrated that the hydroxylations can occur after the proline-rich and lysine-rich polypeptide precursor protocollagen is released from ribosomal complexes^1,2. There has been controversy, however, over the question of whether in uninhibited systems the hydroxylation of the appropriate prolyl and lysyl residues occurs while nascent polypeptide chains are still being assembled on ribosomes^1,3,4.     

Ecologic stability of the dysaerobic biofacies during the Late Paleozoic

Late Paleozoic faunas found in sediments of dysaerobic origin represent a unique community type that remained essentially unchanged from the Middle Devonian to the Early Permian. This dysaerobic community had the following unique characteristics: (1) dominance by vagile molluscs, with suspension-feeding brachiopods, bryozoans, corals and echinoderms usually subordinate; (2) a trophic structure dominated by deposit feeders and carnivorous or scavenging cephalopods; (3) small body size as the result of high juvenile mortality and possibly stunting; and (4) preservation of most individuals as pyritic stein-kerns. All these characteristics are directly linked to the low oxygen levels of the dysaerobic environment. The relative stability of the deeper water, dysaerobic environment is consistent with Sanders' Stability-Time Hypothesis. The dysaerobic environment apparently offered a refuge for more archaic biotas that evolved in nearshore environments of the early Paleozoic.     

Observations on the Development and Fine Structure of the Articulated Laticifers of Papaver somniferum

The development and fine structure of articulated anastomosinglaticifers in Papaver somniferum were studied. Laticifers arenot present in the embryos but differentiate soon after germinationand are found in the phloem areas 18–30 h after the seedis sown. Laticifers and sieve elements are generally separatedby at least one cell layer in the roots, but in cotyledons,stems, and leaves they usually occur adjacent to each other. As the laticifers differentiate an abundance of vesicles formsin the cytoplasm. This process appears to involve the endoplasmicreticulum and it is suggested that the vesicles may be a specializedform of vacuole. Substances present in the vesicles react stronglywith iodine-potassium iodide. Laticifer-cytoplasm persists peripherallyand between the vesicles. It contains the usual cell organelles,the presence of which substantiates an active metabolic rolefor the laticifer contents.