Comparing free-ranging and captive populations reveals intra-specific variation in aging rates in large herbivores

Although evidence that survival decreases with age in animal species is compelling, the existence of variation in aging rates across different populations of a given species is still questioned. Here, we compared aging rates of 22 pairs of ruminant species living in captive and free-ranging conditions. Based on the recent suggestion that feeding niche is a key factor influencing aging in captivity, we also investigated whether a species' natural diet influences the aging rates of captive ruminants relative to their wild conspecifics. We found that aging rate in a given species was higher under free-ranging conditions than in captivity, which provides the first evidence of consistent aging rate variation within species. Additionally, our study clearly demonstrates that differences in aging rates between captive and free-ranging ruminants increased as species were more specialized on grass diets.     

Extra- and intracellular free iron and the carotid body responses

The hypothesis that chelation of free iron, by decreasing reactive oxygen species (ROS), might mimic hypoxia and stimulate the carotid body was tested. We used the iron chelators, desferrioxamine (DFO, 200-400 microM) initially, and later ciclopirox olamine (CPX, 2.5-5.0 microM), on rat carotid body in vitro and measured chemosensory activity and [Ca2+]i in isolated cultured glomus cell clusters during normoxia and hypoxia. Although acute treatment of DFO might not penetrate the cell, and extracellular DFO would not influence these activities whereas CPX significantly increased chemosensory activities as well as increased [Ca2+]i in normoxia. We concluded that chelation of extracellular free iron did not alter ROS formation and oxygen sensing. Chelation of intracellular free iron and, therefore, a decrease in intracellular ROS appears to influence oxygen sensing in the carotid body.     

The pterygoid and ectopterygoid in mammals

Summary A dorsal pterygoid element and a ventral ectopterygoid element can be recognised during the development of monotremes, marsupials and eutherian mammals. Their homology with the elements so named in fossils ancestral to mammals can be established by positional evidence. In monotremes the elements remain distinct and show specialised features, including a hamular cartilage in the ectopterygoid of one specimen of Ornithorhynchus. In most higher mammals the pterygoid element is much reduced and is replaced anteriorly by the perpendicular plate of the palatine. Posteriorly the pterygoid element fuses with the ectopterygoid, in many cases before the onset of ossification. The hamular cartilage arises by chondrification within the ectopterygoid element and shows no sign of being a separate morphological entity, but must be regarded as a specialised feature associated with the architecture of the palatal musculature. There is a strong case for the value of recognising that the pterygoid process of higher mammals includes both a pterygoid and an ectopterygoid moiety.     

Odor psychophysics in vertebrates

The methods used to obtain psychophysical data on the nasal chemosensory systems of all classes of vertebrates are critically reviewed and a summary of the available data on their odor detection and discrimination abilities is provided. Although there are reliable methods for training at least one member of each class to respond differentially to the presence or absence of odor stimuli, very little is known about the limits of the capacity of any of the three major nasal chemosensory systems (olfactory, vomeronasal and trigeminal) to detect pure compounds. Furthermore, studies in which rigorous procedures are followed for both the maintenance of discriminative responding and the presentation of odor stimuli often fail to determine the sensory system(s) mediating the psychophysical results. This lack of information has impeded progress on several fundamental problems in the study of nasal chemoreception.     

Placentophagia: a biobehavioral enigma (or De gustibus non disputandum est)

Although ingestion of the afterbirth during delivery is a reliable component of parturitional behavior of mothers in most mammalian species, we know almost nothing of the direct causes or consequences of the act. Traditional explanations of placentophagia, such as general or specific hunger, are discussed and evaluated in light of recent experimental results. Next, research is reviewed which has attempted to distinguish between placentophagia as a maternal behavior and placentophagia as an ingestive behavior. Finally, consequences of the behavior, which may also be viewed as ultimate causes in an evolutionary sense, are considered, such as the possibility of beneficial effects on maternal behavior or reproductive competence, on protection against predators, and on immunological protection afforded either the mother or the young.     

A contribution to the comparative biochemistry of vertebrate serum cholinesterases

The activities, substrate specificities, and reactivities with third compounds were tested with serum cholinesterases obtained from 32 warm-blooded animal species, some of which were being investigated for the first time. According to the enzyme properties a classification of the animals is attempted. The first group, consisting of a horse, donkey, mule, and zebra, was found to be entirely different from the ruminants. The rodents exhibited a rather diversified type of serum cholinesterase. The two kangaroo species examined were found to be unique with regard to a relatively strong inhibition by butanol, and the unexpected activation by choline was a prominent characteristic of many bird serum cholinesterases.     

The distribution of hypoglossal motoneurons in the dog, rabbit and rat

Summary The distribution of motoneurons innervating the extrinsic tongue muscles was studied in the dog, rabbit and rat using the horseradish peroxidase technique. In these mammals, hypoglossal motoneurons were clustered in roughly ventral (or media) and dorsal (or lateral) groups. Axons of hypoglossal motoneurons in the ventral (or medial) group passed via the medial branch of the hypoglossal nerve, and those in the dorsal (or lateral) group by way of the lateral branch of the hypoglossal nerve. Motoneurons supplying the geniohyoid or genioglossus muscle were distributed, respectively, in the ventral or lateral aspect of the ventral (or medial) cluster of hypoglossal motoneurons. Hyoglossus and styloglossus motoneurons were located in the lateral aspect of the dorsal (or lateral) cluster. The area of distribution of hypoglossus motoneurons overlapped with that of styloglossus motoneurons. It seems likely that motoneurons innervating intrinsic tongue muscles form the remainder of the hypoglossal nucleus. The largest motoneurons in the hypoglossal nucleus were distributed in the cluster of geniohyoid motoneurons. Thus, in the present study a somatotopic arrangement of motoneurons innervating the extrinsic tongue muscles was found, in keeping with previous studies using the retrograde cell degeneration technique.     

Failure to detect radioimmunoassayable arginine vasotocin in mammalian pineals

The presence of arginine vasopressin (AVP) and arginine vasotocin (AVT) in pineal and neural lobes of a variety of species was evaluated by radioimmunoassay using two antisera. One antiserum recognizes only AVP, while the other cross-reacts 100% with both AVP and AVT. Only traces of AVP were detected in toad and chicken pituitaries and chicken pineals, tissues found to contain abundant AVT. On the other hand, pineals from rats and rabbits, while containing measurable quantities of AVP, did not contain detectable levels (less than 6 pg) of AVT. These results fail to demonstrate the presence of AVT in rat and rabbit pineals and strongly question the role of AVT as a physiological pineal hormone in mammals.     

六种哺乳类动物肝细胞内溶酶体形态的比较研究

本文用电镜、酸性磷酸酶ACPase组化和立体计量分析,对成年猴、狗、猫、兔、大鼠和小鼠肝细胞内溶酶体作了超微结构定性和定量的比较观测。 几种动物肝细胞的致密体超微结构相似,但数量和大小各有差别。消化泡以大鼠、小鼠、兔和猴的数量最多,狗和猫的较少。与此相反,大鼠、小鼠和兔的殁体较少见,猫和猴的稍多,狗的残体为数最多,且见有在其旁的未消化物质正进入残体内进行消化。这几种哺乳类动物肝细胞内消化泡与残体所出现的差别,据推测可能与所食饲料的性质和动物种属不同有关。 鬃毛有衣小泡多位于细胞膜的深处。在狗和猴见到侧邻的两个肝细胞的一侧胞膜出芽,陷入胞质内,其末端膨大,似脱离而形成鬃毛有衣小泡。 6种哺乳类动物肝细胞内溶酶体的形态计量分析所得结果;体积密度中,以狗为最高,小鼠最低;数目密度中,猴最高,兔最低。