Biogeography of time partitioning in mammals

Many animals regulate their activity over a 24-h sleep–wake cycle, concentrating their peak periods of activity to coincide with the hours of daylight, darkness, or twilight, or using different periods of light and darkness in more complex ways. These behavioral differences, which are in themselves functional traits, are associated with suites of physiological and morphological adaptations with implications for the ecological roles of species. The biogeography of diel time partitioning is, however, poorly understood. Here, we document basic biogeographic patterns of time partitioning by mammals and ecologically relevant large-scale patterns of natural variation in “illuminated activity time” constrained by temperature, and we determine how well the first of these are predicted by the second. Although the majority of mammals are nocturnal, the distributions of diurnal and crepuscular species richness are strongly associated with the availability of biologically useful daylight and twilight, respectively. Cathemerality is associated with relatively long hours of daylight and twilight in the northern Holarctic region, whereas the proportion of nocturnal species is highest in arid regions and lowest at extreme high altitudes. Although thermal constraints on activity have been identified as key to the distributions of organisms, constraints due to functional adaptation to the light environment are less well studied. Global patterns in diversity are constrained by the availability of the temporal niche; disruption of these constraints by the spread of artificial lighting and anthropogenic climate change, and the potential effects on time partitioning, are likely to be critical influences on species’ future distributions.Natural cycles of light and darkness structure the environment of the majority of eukaryotic organisms. The rotation of the Earth partitions time into regular cycles of day and night, and although all points on the Earth’s surface receive roughly equal durations of light and darkness over the course of a year, at mid to high latitudes seasonal variation in day length imposes an uneven distribution throughout the annual cycle. During the hours when the sun is below the horizon, there is seasonal and latitudinal variation in the duration of “biologically useful semidarkness” in the form of twilight and moonlight (1), modified by both the lunar cycle and variable cloud cover, providing changing opportunities for animals able to use visual cues for key behaviors including foraging, predator avoidance, and reproduction (2–6). Activity during both daylight and semidarkness may be further constrained by covariance between the natural cycles of light and temperature; the metabolic costs of thermoregulation place constraints on the time available for activity (7). Thermal constraints may limit nocturnal activity when nighttime temperatures are low, and diurnal activity when temperatures are high. Furthermore, energetic constraints may force some species to be active throughout hours of both light and darkness (8). Where energetic and thermal costs are not prohibitive, temporal niche partitioning may occur as species specialize and avoid competition by concentrating their activity within a particular section along the light gradient (9, 10). Behavioral traits are associated with a range of specialized adaptations, particularly in visual systems and eye morphology (11) and energetics and resource use (6, 12). Thus, some species are apparently obligately diurnal in their peak activity patterns, some obligately nocturnal, obligately crepuscular (active primarily during twilight), or obligately cathemeral (significant activity both during daylight and night), and others make facultative use of both daylight and night (13), or show seasonal and/or geographical variation in their strategy. Strict nocturnality and diurnality are hence two ends of a continuum of possible strategies for partitioning time over the 24-h cycle. As properties of organisms that strongly influence performance within a particular environment, these strategies can be considered functional traits in themselves (14), but are also associated with suites of adaptations, with implications for the ecological roles of species and individuals. Crepuscular and cathemeral species may have intermediate adaptations (15), and behavior may be flexible to vary within species and among individuals according to factors such as time of year, habitat structure, food availability, age, temperature, and the presence or absence of predators (16–18).The ecology of diel time partitioning by organisms remains rather poorly understood (19, 20). Studies have considered the adaptive mechanisms behind strategies within a single ecosystem, including predator avoidance, energetic constraints, diet quality, and interspecific competition (9, 21). Meanwhile, although mapping functional traits has become a core technique in functional biogeography (22, 23), surprisingly little is known about the biogeography of diel activity patterns, and the extent to which they are determined by geographic gradients in light and climate. Addressing such issues has become more pressing with growth in the evidence for a wide range of ecological impacts of both anthropogenic climatic change and nighttime light pollution (24–28). Natural cycles of light have remained consistent for extremely long geological periods, providing a rather invariant context, and a very reliable set of potential environmental cues. The continued spread of electric lighting has caused substantial disruption to how these cycles are experienced by many organisms, exerting a novel environmental pressure (29). Direct illumination of the environment has quite localized effects, but sky glow—the amplified night sky brightness that is produced by upwardly emitted and reflected electric light being scattered by water, dust, and gas molecules in the atmosphere—can alter light regimes over extensive areas. Indeed, under cloudy conditions in urban areas, sky glow has been shown to be of an equivalent or greater magnitude than high-elevation summer moonlight (30). Understanding the biogeography of time partitioning by organisms provides a first step toward determining where such changes are likely to have the greatest impact.In this paper, we (i) document basic biogeographic patterns of time partitioning by organisms, using terrestrial mammals as a case study; (ii) document ecologically relevant large-scale patterns of natural variation in “biologically useful” natural light, constrained by temperature; and (iii) determine how well the first of these are predicted by the second. Mammals provide an interesting study group, being globally distributed, occupying a broad range of environments, and exhibiting a wide diversity of time-partitioning behavior. Much concern has also been expressed as to the potential impacts of nighttime light pollution on the group, and there are many studies documenting significant influences (31, 32). Due to the global nature of this study, and the paucity of detailed information on time partitioning reported for many species, our focus is on a high-level categorization, allocating species to one of four temporal niches: nocturnal, diurnal, cathemeral, and crepuscular (Fig. 1), albeit with the acknowledgment that in many species behavior occurs along a continuum of possible strategies that may be more flexible and complex.Open in a separate windowFig. 1.Examples of recorded diel activity patterns illustrating the four main time-partitioning strategies used to classify terrestrial mammals in this study (64–67).     

The Production of High Affinity Monoclonal Antibodies to Human Chorionic Gonadotropin and Their Application to Immunoradiometric Assay

Abstract

Production of monoclonal antibodies against hCG has been studied using hCG as the antigen. This study reports the successful isolation of hybrid clones secreting monoclonal antibodies specific for hCG with an affinity constant higher than 10¹⁰M^?l. Of 23 fusions, only 17 fusions have produced positive clones which secrete antibodies giving high levels of binding with ^l25I-labelled hCG in the supernatant. Finally, 6 different monoclonal antibodies have been isolated; 4 of them, specific for the β-subunit, with a Ka approximately 1.1–4.0 ± 10¹¹M^?1 and 2 others, specific for the α-subunit, presenting an affinity of 2.5 ± 10¹⁰M^?l. When the antibodies specific for the β-subunit are used, specific and highly sensitive radioim-munoassays are obtained after only 3 hrs of incubation. Using iodinated monoclonal antibodies specific for the α-subunit and tubes coated with antibodies against the β-subunit, we have developped sensitive immunoradiometric assays.     

Eruption of the central incisor,the intermaxillary suture,and maxillary growth in patients with a single median maxillary central incisor

The occurrence of a single median maxillary central incisor (SMMCI) is a very rare condition and might be a sign of a more severe midline defect, which could be a mild degree of holoprosencephaly. Absence of the internasal and partial absence of the intermaxillary suture has been observed in a fetus with holoprosencephaly. The purpose of this study was to evaluate the intermaxillary suture, the eruption pattern of the single central incisor in the SMMCI condition, and the growth of the maxilla in a group of patients with SMMCI. A similar study was not found in the scientific literature. The material included orthopantomographs, dental radiographs, and lateral cephalometric radiographs from 11 patients with an SMMCI. The orthopantomographs and dental radiographs showed that the intermaxillary suture was abnormal anterior to the incisive foramen; however, the SMMCI erupted within the expected time interval. Superimposition on stable structures on lateral cephalometric radiographs from two untreated patients, in which growth analysis was possible, showed that the horizontal and vertical growth of the maxilla was normal. Due to the sutural midline defect it is suggested that a transversal growth analysis is included in all treatment planning of SMMCI patients.     

Dental auscultation for nursing personnel as a model of oral health care education: development,baseline, and 6-month follow-up assessments

Oral health care has been shown to have low priority in nursing and has been only partly successful. To create more positive effects than those achieved through traditional oral health care education, this project tested an educational model for nursing staff personnel. In addition to traditional oral health care education, some of the nursing staff members passed an additional dental auscultation period and served as oral care aides. The aides were responsible for the oral health care of the residents at their nursing facilities (intervention group). The intervention nursing facilities were compared with facilities where nursing personnel only received a traditional oral health care education program. Assessments were made at baseline and at a 6-month follow-up. At follow-up it was shown that the nursing staff in the intervention group gave higher priority to the oral health care work than the nursing staff in the control group.     

Sleep apnoea, anxiety, depression and somatoform pain: a community-based high-risk sample

Community-based studies that measure both psychiatric diagnoses and obstructive sleep apnoea (OSA) are lacking. This study reports current psychiatric disorders in community-dwelling adults at high risk for OSA identified by the Berlin Questionnaire. Furthermore, associations between OSA and current psychiatric disorders, unadjusted and adjusted for putative confounders, are reported. A subsample of the Akershus Sleep Apnoea Project consisting of 290 adults, aged 30-65 yrs, with positive Berlin Questionnaire screening underwent the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, version IV and polysomnography. Auxiliary analyses of depression are provided. The median apnoea/hypopnoea index score in the sample was 7.7 (interquartile range 2.4-22.2). Major depressive disorder, current anxiety and somatoform pain disorder were diagnosed in 12.4%, 14.8% and 19.3% of participants, respectively. At least one psychiatric disorder was diagnosed in 110 participants. The odds ratio of participants with OSA having a psychiatric disorder compared with participants without OSA was 0.54 (95% CI 0.33-0.88). A negative association did not exist among Berlin Questionnaire low-risk participants. In conclusion, more than one-third of participants in a community-based, Berlin Questionnaire high-risk sample were diagnosed with a psychiatric disorder. A negative association between OSA and psychiatric morbidity was found.     

The Copeland resurfacing humeral head implant does not restore humeral head anatomy. A retrospective study

Purpose

Recently, there has been concern that the Copeland resurfacing humeral head implant (RHHI) leaves the shoulder joint overstuffed. The purpose of this study was in a selected cohort of patients operated with a Copeland RHHI (1) to evaluate the Length of the Gleno-Humeral Offset (LGHO), (2) to assess the patient-reported quality of life and functional outcome measured by Western Ontario Osteoarthritis of the Shoulder Index (WOOS) and (3) to determine the number of revisions in the cohort.

Methods

Pre- and postoperative radiographs were retrieved from 71 of 91 possible patients operated with a Copeland RHHI from 2005 to 2009. The cohort consisted of 30 males and 41 females at a mean age of 61 (38–89) years. One radiologist measured the LGHO and performed double measurements. The WOOS score 1 year after surgery and the number of revisions from all patients operated with a Copeland RHHI in Denmark was requested from the Danish Shoulder Arthroplasty Registry.

Results

The mean LGHO was 4.99 ± 0.53 cm before surgery and 5.39 ± 0.58 cm after surgery, (p < 0.001). 95 % limits of agreement for measurements of LGHO were ± 0.11 cm. One year after surgery, the WOOS score was 67 for the cohort and 64 for all patients operated with a Copeland RHHI in Denmark. 13 of 71 RHHI in the cohort were revised.

Conclusion

The Copeland RHHI causes significantly increased LGHO and leads to overstuffing in the shoulder joint. The WOOS score in the cohort was comparable to that for all other Danish patients operated with a Copeland RHHI.