bluuebunny/crossref_metadata_2025 huggingface dataset:
Spontaneous and induced ovulation in the lion (Panthera leo)
Authors: Schramm Ralph Dee , Briggs Michael B. , Reeves Jerry J.
Published: June 2005

The objective of this study was to clarify if ovulation occurs spontaneously, if it is copulation‐induced, or if a combination of both mechanisms controls ovulation in African lions. Five female lions were either permitted unrestricted copulatory activity with vasectomized males throughout estrus or were physically isolated from conspecifies for the duration of estrus. Each female was randomly exposed to each treatment in a switchback design during consecutive estrous cycles. Serum concentrations of progesterone were determined in blood samples collected on days 2, 8, 12, and 16 following the onset of estrus (day 0). Ovulation was indirectly confirmed by elevated serum concentrations of progesterone on days 8, 12, and 16. While ovulation occurred spontaneously in one of five isolated lions, five of five of the same lions ovulated following copulation (P ≤ 0.05). Following mating, concentrations of progesterone increased six‐ to twelve fold (up to > 109 ng/ml) between days 2 and 12, while in the same lions failing to ovulate following isolation, progesterone concentrations did not exceed 11 ng/ml by day 16. Inter‐estrous intervals following mating (67 ± 4.4 days) were longer (P ± 0.05) than those following isolation (19 ± 1.0 day). Thus, ovulation in African lions appears to be induced by copulatory stimuli or some other form of physical or social interaction with conspecifies during estrus but can occasionally occur spontaneously. The lion, therefore, does not appear to be a classic spontaneous ovulator but rather a reflex ovulator like the domestic cat. © 1994 Wiley‐Liss, Inc.
Reactions of zoo visitors to free‐ranging monkeys
Authors: Price Eluned C. , Ashmore Louise A. , McGivern Anne‐Marie
Published: June 2005

This study assessed the potential of two types of primate exhibit both for enhancing zoo visitors' interest, knowledge, and enjoyment and for promoting conservation education. Visitors' reactions to a free‐ranging group of cotton‐top tamarins were compared with their responses to caged tamarins in three ways: 1) timing how long visitors spent at each exhibit, 2) recording the comments made by visitors about the exhibits, and 3) asking visitors to respond to questionnaires about the two exhibits. The results showed that the free‐ranging group of tamarins provoked wider comment from members of the public than caged groups and that visitors were willing to spend much more time looking for and watching monkeys in trees than monkeys in cages. Visitors felt that improvements in the animals' welfare were obtained from allowing them to live free in the trees, thought that they could learn more from such groups than from caged animals, and enjoyed seeing the free‐ranging tamarins more than the monkeys in cages. These results suggest that developing more naturalistic zoo exhibits can have considerable benefits not only for the animals involved, but also for public education in conservation issues. © 1994 Wiley‐Liss, Inc.
Asian elephant (Elephas maximus) milk composition during the first 280 days of lactation
Authors: Mainka Susan A. , Cooper Robert M. , Black Sandra R. , Dierenfeld Ellen S.
Published: June 2005

Milk samples (n = 10) taken during the first 280 days of lactation from one Asian elephant were examined for nutrient composition including total solids, protein, fat, ash, α‐tocopherol, and retinol levels. Total solids averaged 19.7 ± 2.7% SD (range 15.0–23.3). Percent protein remained fairly stable throughout this portion of lactation and averaged 3.4 ± 0.3% (range 3.0–.4.0). Ash content averaged 0.54 ± 0.03%. Milk fat and fat soluble vitamin levels varied considerably with a suggestion of a cyclic pattern. Fat content of milk averaged 7.6 ± 2.6% (range 3.9–.12.1); α‐tocopheral levels averaged 0.33 ± 0.12 μg/ml; and retinol levels averaged 0.46 ± 0.1 μg/ml. © 1994 Wiley‐Liss, Inc.
Use of behavior to evaluate reproductive problems in captive mammals
Authors: Lindburg Donald G. , Fitch‐Snyder Helena
Published: June 2005

Behavioral analyses constitute a logical starting point for discerning the causes of reproductive failure in captive mammals and should be completed before moving on to more invasive diagnostic procedures. Behavioral inadequacies affecting reproductive performance may be attributable to deficient early rearing environments, to the social milieux in which breeding‐age animals are held on a long‐term basis, or in the way pairings for mating are staged. Diagnoses may be focused on uncovering motivational, motoric, social, or communicative deficiencies. A biologically based approach which integrates species‐typical behavior with concerns for genetics, physiology, and health in designing breeding programs will improve prospects for success. © 1994 Wiley‐Liss, Inc.
Effects of environmental enrichment on reproduction
Authors: Carlstead Kathy , Shepherdson David
Published: June 2005

Although there have been few demonstrations of a direct empirical relationship between environmental enrichment and reproductive success in captive animals, indirect and anecdotal evidence indicates the importance of physical and temporal complexity for reproduction. We discuss three major mechanisms through which environmental enrichment that specifically increases the complexity of an animal's surroundings may influence reproductive physiology and behavior: developmental processes, modulation of stress and arousal, and modification of social interactions. In complex environments developing animals learn that performing active behavior produces appropriate functional outcomes. Learning to control their environment influences their ability to adapt to novel situations, which may profoundly influence their reproductive behavior as adults in breeding situations. Chronic stress may compromise reproductive physiology and behavior; enrichment reduces stress by providing increased opportunity for behavioral coping responses. However, some degree of acute stress may be beneficial for reproduction by maintaining an animal's level of responsiveness to socio‐sexual stimuli necessary for sexual arousal and reproductive activation. Finally, environmental enrichment may influence reproductive success by stabilizing social groups, reducing aggression and increasing affiliative and play behaviors. It is concluded that multi‐variate multi‐institutional behavioral research in zoos will play an increasingly important role in the successful captive propagation of many species by closely examining relationships between environmental variables and reproductive potential of individual animals. © 1994 Wiley‐Liss, Inc.
Survey and interzoo studies used to address husbandry problems in some zoo vertebrates
Authors: Mellen Jill D.
Published: June 2005

In addition to genetic and demographic considerations, SSP coordinators have been asked to systematically address husbandry issues. Three approaches to the study of captive management issues are typically used: (1) large numbers of individuals are housed at a single institution maintained in a situation that facilitates systematic evaluation of the captive environment, (2) an investigator travels to many institutions to gather data on a single taxon, or (3) an investigator surveys existing information by assembling data from a large number of individuals at a variety of institutions. Each approach has both advantages and disadvantages in terms of feasibility and the type of results obtained. The use of surveys to obtain information about husbandry parameters from a large number of animals maintained at a variety of zoos is quite possibly the most common approach used among zoo managers. Zoo husbandry surveys are typically developed to address issues problematic to a particular species, including reproductive failure and health issues. Unfortunately, surveys appear to be an often misused research tool among zoo professionals. Surveys can be improved by working with psychologists or sociologists at local universities, by narrowing the focus of the survey's purpose, and by carefully constructing each question. © 1994 Wiley‐Liss, Inc.
Managing the social environments of flamingos for reproductive success
Authors: Stevens Elizabeth F. , Pickett Charles
Published: June 2005

Recent research has shown that large flamingo flocks are more likely to experience reproductive success than small flocks and that there is a positive relationship between behavioral stimulation from group displays and reproductive success. This study compares the group displays and reproductive success in a captive flock of Caribbean flamingos over 6 years at the National Zoological Park. Birds were added to the flock in two different years. In each case, the flock produced fertile eggs during the breeding season following the addition of new birds. Furthermore, the addition of new birds in 1988, and then again in 1991, significantly increased group display activity over the previous year when the flock size was lower. That the addition of birds stimulated group display activity suggests an alternative management strategy for promoting reproduction in captivity: separate birds in a flock and then reunite them prior to the breeding season. © 1994 Wiley‐Liss, Inc.
Under‐ice observations of behavior of selected native and exotic fishes of the St. Lawrence river system
Authors: Whoriskey F. G. , Brown K.
Published: June 2005

Winter behavior of two native fishes (yellow perch, Perca flavescens, and killifish, Fundulus heteroclitus) and an exotic (goldfish, Carassius auratus) were studied in an outdoor experimental pond to quantify and link behavior to environmental conditions, and to identify interactions among the species that now co‐occur in the wild. Killifish had high mortality and were not observed. However, contrary to our predictions, perch and goldfish had good overwinter survival and remained active in winter, and neither species spent most of their time in the warmest layer of the water column. Only two instances of aggression were seen: in both, goldfish charged perch. Both species were found principally in groups (schools); goldfish spent 18% of their time in multispecies groups. © 1994 Wiley‐Liss, Inc.
Mother‐cub relationships in giant pandas in the Qinling Mountains, China, with comment on rescuing abandoned cubs
Authors: Lu Zhi , Pan Wenshi , Harkness Jim
Published: June 2005

Six cases of mother‐cub relationships in wild giant pandas (Ailuropoda melanoleuca) were observed in the Qinling Mountains, China. It was found that panda cubs are normally left alone in the den for 4–8 h while mothers forage. The mother's absence during bouts of foraging should be considered when rescuing abandoned cubs in order to avoid adding to the decline of the wild population. © 1994 Wiley‐Liss, Inc.
Reproductive parameters of mandrills at the Tulsa Zoo
Authors: Bettinger Tammie , Wallis Janette , Morris Amy
Published: June 2005

The genital swelling patterns and birth records of female mandrills housed at the Tulsa Zoo between 1979 and 1992 were examined to determine various reproductive parameters. Mean age at first adolescent genital swelling was 2.7 years (sd = .55), first adult swelling was 3.7 years (sd = .64), and first conception was 5.1 years (sd = 1.30). Genital swelling cycle duration averaged 39.6 days (n = 33 cycles), with the swelling phase averaging 19.5 days (n = 51 cycles). There was no interindividual difference in cycle length (F = 1.26, P = .31) or swelling duration (F = 0.65, P = .58), nor was there a difference in cycle length (F = 0.47, P = .50) or swelling duration (F = 1.27, P = .27) before and after first parturition. Duration of gestation was estimated to be 165.9 days (sd = 3.3; n = 17 pregnancies). Lactational anestrus averaged 10.1 months, whereas mean interbirth interval was 17.9 months (n = 11). There was a significant negative correlation between age of the mother and interbirth interval (r = −;0.648, P = .03). Data presented in this report provide a comprehensive profile of reproductive parameters for zoo‐housed mandrills, which may aid other facilities in the reproductive management of their captive groups. © 1995 Wiley‐Liss, Inc.
Infant development in two aquarium bottlenose dolphins
Authors: Reid Kylie , Mann Janet , Weiner Jacqueline R. , Hecker Nedra
Published: June 2005

The behavioral development of two aquarium bottlenose dolphin calves, one male (born to a primiparous mother) and one female (born to a multiparous mother), was examined. From birth to 9 weeks of age, a total of 558.7 h of nursing and behavioral data were collected using focal sampling methods. Data from both calves revealed a pattern of increasing independence as they aged, but there were significant differences between the two calves. Suckling rates, mean suckles per bout, suckling bout rates, and bout durations for the male calf were higher than those for the female calf throughout the study. These frequencies declined significantly over time in the male's case but not in the female's case. Her suckling durations (lock‐on time) were longer than his. The male spent more time in infant position (under the mother) than the female calf and less time swimming in echelon position (alongside the mother). Over time, the male spent less time in infant position, and the female calf spent more time socializing and less time echelon swimming. Both calves decreased the amount of time spent close to their mothers over the 9 week period, and the mothers decreased their role in proximity maintenance over time. We suggest that factors related to maternal primiparity caused the male calf to develop an effective compensatory response of frequent nursing and spending more time in infant position. Both calves survived and were healthy at the end of the observation period. © 1995 Wiley‐Liss, Inc.
Giant panda diets fed in five Chinese facilities: An assessment
Authors: Dierenfeld Ellen S. , Qiu Xianmeng , Mainka Susan A. , Liu Wei‐Xin
Published: June 2005

Information on diets fed to captive giant pandas in five Chinese facilities (Beijing Zoo, Chengdu Zoo, China Conservation and Research Center, Fuzhou Zoo, and the Xian Zoo for the Giant Panda) in which pandas have successfully reproduced was compiled from publications and/or personal communications. Each facility feeds a steamed grain mixture comprising 13–56% of the diet on an as‐fed basis, animal products (milk, eggs, and/or meat; 8–25% of the diet), and bamboo (17–82% of the diet). Seasonally available fruits and/or vegetables are sometimes included (0–29% of the diet). Typically, bamboo is offered throughout the day in small increments, while the remaining diet (concentrate portion) is fed in two meals. Despite the variety of ingredients in the concentrate recipes among institutions, there was remarkable similarity in nutrient composition: 55–65% water, 13–19% crude protein (CP), 2.5–4.0% crude fat (CF), and 2–5% ash (Ca, 0.2–0.9%; P, 0.4–0.8%) (all nutrients except water expressed on a dry matter (DM) basis). Calculated digestible energy content averaged about 3.3 kcal/kg DM. With the addition of animal products, bamboo, and produce, total diet composition averaged 51% water and, on a DM basis, 12% CP, 5.0% CF, 20–57% NDF (fiber), 0.5% Ca, 0.4% P, and 50–150 mg/kg vitamin E. These specifications are similar to nutrient requirements established for domestic canids and would appear adequate to meet the (as yet unestablished) requirements of the giant panda in captivity. Formulations for mineral and vitamin supplements to balance concentrate portions of these basic diets are included. © 1995 Wiley‐Liss, Inc.
Assessment of conservation units for the Sumatran rhinoceros (Dicerorhinus sumatrensis)
Authors: Amato George , Wharton Dan , Zainuddin Zainal Z. , Powell Jeffery R.
Published: June 2005

An assessment of conservation units for the Sumatran rhinoceros (Dicerorhinus sumatrensis) was conducted using a population aggregation analysis (PAA) of mitochondrial DNA site substitutions. Populations were defined as the three geographically separated regions of West Malaysia, Sumatra, and Borneo. The intent of this assessment was to explore management options for this highly endangered lineage rather than conduct a traditional taxonomic revision.

Individual DNA positions were not diagnostic for any population. A single haplotype provided a character as support for diagnosing the West Malaysian and Bornean population. The haplotypes on West Malaysia and Sumatra were more similar to each other than either was to the one on Borneo. These data, and a review of the morphological characters, support the option of treating Sumatran rhinos as a single conservation unit, providing managers with greater flexibility in managing the unique Dicerorhine lineage. © 1995 Wiley‐Liss, Inc.
Killer whale (Orcinus orca) reproduction at Sea World
Authors: Duffield Deborah A. , Odell Daniel K. , McBain James F. , Andrews Brad
Published: June 2005

Sea World has maintained killer whales (Orcinus orca) since 1965. The total killer whale inventory (1965–1993) has included 39 whales (25 females, 14 males); 28 were wild‐caught and 11 captive‐born, including one second‐generation calf. As of September, 1993, there were 19 whales in the breeding program. Ten of these whales (53%) were captive‐born, either at Sea World or other facilities in North America. The live wild‐caught whales ranged in estimated age from 12–27 years (x̄ ± sd = 17.6 ± 4.2 years). The captive‐born whales ranged in age from <1 to 8 years. In the Sea World breeding program (through September, 1993), there have been nine live births and one stillbirth, with eight calves part of the current inventory. Births occurred from July to February. Calving intervals ranged from 32–58 months. Female age at birth of first calves ranged from 8 years to an estimated 17 years (x̄ ± sd = 12.7 ± 3.0 years). Gestation, based on conception estimates from serum progesterone analysis, averaged 17 months (x̄ ± sd = 517 ± 20 days), but successful pregnancies with viable calves occurred from 15–18 months (468–539 days). Females, in the presence and absence of males, were polyestrus with periods of cycling interspersed with individually variable noncycling (presumed anestrous) periods ranging from 3–16 months. Mean serum progesterone levels (±se) were as follows: noncycling periods = 121 ± 20 pg/ml; peak elevations during nonconceptive ovulatory (estrous) cycles = 3,962 ± 2,280 pg/ml; first pregnancies = 14,592 ± 3,854 pg/ml; second pregnancies = 8,389 ± 395 pg/ml; and third pregnancy = 8,180 ± 4,556. © 1995 Wiley‐Liss, Inc.
Derivation of diurnal courses of albedo and reflected solar irradiance from airborne POLDER data acquired near solar noon
Authors: Jacob Frédéric , Olioso Albert
Published: June 2005

Knowledge of the diurnal course of land surface albedo is needed for monitoring radiative transfers between soil, vegetation, and atmosphere. These transfers are of interest for crop monitoring, hydrological cycle modeling, weather forecast, and climate modeling. The required absolute accuracy ranges between 0.02 and 0.05. At the present time, it is possible to derive the diurnal course of albedo from geostationary satellites. Sun‐synchronous sensors, with higher spatial resolutions, allow retrieving surface radiative properties by both discriminating different types of land cover and capturing the subclass variability. However, the current possibilities for deriving the diurnal course of albedo from Sun‐synchronous observations are empirical or mathematically complex. We proposed in this paper a physically based method, which is candidate for operational use along with multiangular Sun‐synchronous sensors, under clear‐sky conditions. This method uses both reciprocal kernel‐driven bidirectional reflectance distribution function (KD BRDF) models and narrowband to broadband (NTB) conversion. It was implemented and validated using the Alpilles‐RESEDA database which was collected over agricultural areas. The implementation was performed using the 20 m spatial resolution airborne POLDER data acquired near midday. The validation was conducted using field measurements of albedo, recorded over the diurnal cycle. The retrievals of the diurnal course of albedo were good, with errors ranging from 0.026 to 0.029. Better results were observed for instantaneous values at solar noon and times close to satellite overpasses as well as for the daily mean value, with errors ranging between 0.014 and 0.022. Among the selected reciprocal KD BRDF models, Li‐Ross systematically provided the best results, regardless of considered albedo product. Further, using instantaneous values at times close to satellite overpasses, in place of the daily mean value, did not yield significant differences, with errors ranging around 0.01. Finally, we assessed the interest of deriving the diurnal course of reflected solar irradiance by using the several albedo products aforementioned. For the environmental conditions of the Alpilles‐RESEDA experiment, the resulting differences were not significant, with accuracies better than 20 W m−2.
Development and evaluation of a sampling system to determine gaseous Mercury fluxes using an aerodynamic micrometeorological gradient method
Authors: Edwards G. C. , Rasmussen P. E. , Schroeder W. H. , Wallace D. M. , Halfpenny‐Mitchell L. , Dias G. M. , Kemp R. J. , Ausma S.
Published: June 2005

An aerodynamic gradient micrometeorological approach to the measurement of total gaseous mercury (TGM) flux has been developed. This method has been applied in many field studies for the characterization of TGM flux from various mercuriferous substrates. The resolution of the gradient method depends on the sampling systems characteristics and has been demonstrated to be on the order of 0.01 ± 0.01 ng Hg m−3 or better. The method is best suited to measuring high‐emitting sites such as studied here. The TGM flux resolution is based on the gradient resolution and depends on the site characteristics and the atmospheric condition. For a typical friction velocity u* of 0.1 m s−1 and gradient intake heights of 0.15 and 0.4 m the method can resolve a TGM flux on the order of 1.5 ng m−2 h−1. The system can be configured for two‐level or multilevel sampling, as needed. The method compares well with other micrometeorological methods as demonstrated during the Nevada storms intercomparison study. The micrometeorological method is shown to compare well with chamber techniques under comparable conditions.
An investigation of the chemistry of ship emission plumes during ITCT 2002
Authors: Chen G. , Huey L. G. , Trainer M. , Nicks D. , Corbett J. , Ryerson T. , Parrish D. , Neuman J. A. , Nowak J. , Tanner D. , Holloway J. , Brock C. , Crawford J. , Olson J. R. , Sullivan A. , Weber R. , Schauffler S. , Donnelly S. , Atlas E. , Roberts J. , Flocke F. , Hübler G. , Fehsenfeld F.
Published: June 2005

A ship emission plume experiment was conducted about 100 km off the California coast during the NOAA Intercontinental Transport and Chemical Transformation (ITCT) 2K2 airborne field campaign. Measurements of chemical species were made from the NOAA WP‐3D aircraft in eight consecutive transects of a ship plume around midday during 2.5 hours of flight. The measured species include NOx, HNO3, peroxyacetylnitrate (PAN), SO2, H2SO4, O3, CO, CO2, nonmethane hydrocarbons (NMHC), and particle number and size distributions. Observations demonstrate a NOx lifetime of ∼1.8 hours inside the ship plume compared to ∼6.5 hours (at noontime) in the moderately polluted background marine boundary layer of the experiment. This confirms the earlier hypothesis of highly enhanced in‐plume NOx destruction. Consequently, one would expect the impact of ship emissions is much less severe than those predicted by global models that do not include rapid NOx destruction. Photochemical model calculations suggest that more than 80% of the NOx loss was due to the NO2 + OH reaction; the remainder was by PAN formation. The model underestimated in‐plume NOx loss rate by about 30%. In addition, a comparison of measured to predicted H2SO4 in the plumes suggests that the photochemical model predicts OH variability reasonably well but may underestimate actual values. Predictions of in‐plume O3 production agree well with the observations, suggesting that model‐predicted peroxy radical (HO2 + RO2) levels are reasonable. The model estimated ozone production efficiency ranges from 6 to 30. The largest model bias was seen in the comparison with measured HNO3. The model overestimated in‐plume HNO3 by about a factor of 6. This is most likely caused by underestimated HNO3 sinks possibly involving particle scavenging. However, limited data availability precluded a conclusive test of this possible loss process.
Multilinear regression analysis of the 65‐year Tromsø total ozone series
Authors: Hansen Georg , Svenøe Trond
Published: June 2005

The 65‐year total ozone record from Tromsø, Norway (69.7°N, 18.9°E), has been analyzed using multiple linear regression. Parameters included are modified linear depletion term, Northern Hemisphere teleconnection patterns, local temperature at the 30‐mbar level, stratospheric aerosols, Quasi‐Biennial Oscillation (QBO), and solar activity. Because of the availability of most input parameters, the analysis was limited to the period 1950–2001. All multiple correlation coefficients found are above 0.7, most even larger than 0.8. The series reveals a linear depletion term of about 9% decrease/decade in March/April since the late 1970s, decreasing to few percent in summer. The depletion term is insensitive to the envelope function (linear versus equivalent effective stratospheric chlorine), but highly sensitive to the modification term, forcing the contribution to zero in years with early vortex breakup. Aerosol‐induced depletion is found throughout late winter and spring, while the QBO is of importance in summer. Midstratospheric conditions, parameterized by the 30‐mbar level temperature, are dominant throughout the winter half year from September to February. Teleconnection patterns reveal a complex contribution, with no single pattern being persistently dominant over several months. The Polar‐Eurasian pattern is most prominent in midwinter, the North Atlantic Oscillation pattern in March. In May, the East Atlantic Jet pattern is dominant, while in June the Pacific Transition pattern is the most prominent parameter in the analysis. This variability of teleconnection pattern contributions is probably caused by the changing influence of air masses on the local tropopause altitude, with a dominant influence of North Atlantic and Arctic patterns in winter/spring, and of lower‐latitude patterns in summer and early autumn.
Compressional and shear wave velocities in uncemented sediment containing gas hydrate
Authors: Yun T. S. , Francisca F. M. , Santamarina J. C. , Ruppel C.
Published: June 2005

The competing hypotheses for gas hydrate formation at the particle scale in sediments describe processes of pore‐filling, frame‐building, or cementation. New measurements of compressional (VP) and shear wave (VS) velocities in fine‐grained sands subjected to low confinement and monitored during formation of tetrahydrofuran hydrate indicate that hydrate nucleates in the pore space (presumably at grain boundaries) and grows with limited impact on the sediment shear stiffness, VP, and VS until crystals begin to interact with the granular skeleton at ∼40% hydrate concentration. VS increases significantly more than VP at higher hydrate concentrations, reflecting larger changes in the specimen's shear stiffness than its bulk stiffness. The results indicate that seismic velocities and/or their ratio (VP/VS) have limited capability for locating hydrate or constraining hydrate concentrations.
Dissociated phenotypes in presenilin transgenic mice define functionally distinct γ-secretases
Authors: Mastrangelo Peter , Mathews Paul M. , Chishti M. Azhar , Schmidt Stephen D. , Gu Yongjun , Yang Jing , Mazzella Matthew J. , Coomaraswamy Janaky , Horne Patrick , Strome Bob , Pelly Heather , Levesque Georges , Ebeling Chris , Jiang Ying , Nixon Ralph A. , Rozmahel Richard , Fraser Paul E. , George-Hyslop Peter St , Carlson George A. , Westaway David
Published: June 2005

γ-secretase depends on presence of presenilins (PS), Nct, Aph-1, and PEN-2 within a core complex. This endoproteolytic activity cleaves within transmembrane domains of amyloid-β precursor protein (APP) and Notch, and familial Alzheimer's disease (FAD) mutations in PS1 or PS2 genes shift APP cleavage from production of amyloid-β (Aβ) 40 peptide to greater production of Aβ42. Although studies in PS1/PS2-deficient embryonic cells define overlapping activities for these proteins,
in vivo
complementation of PS1-deficient animals described here reveals an unexpected spectrum of activities dictated by PS1 and PS2 alleles. Unlike PS1 transgenes, wild-type PS2 transgenes expressed in the mouse CNS support little Aβ40 or Aβ42 production, and FAD PS2 alleles support robust production of only Aβ42. Although wild-type PS2 transgenes failed to rescue Notch-associated skeletal defects in PS1 hypomorphs, a “gained” competence in this regard was apparent for FAD alleles of PS2. The range of discrete and divergent processing activities in mice reconstituted with different PS genes and alleles argues against γ-secretase being a single enzyme with intrinsically relaxed substrate and cleavage site specificities. Instead, our studies define functionally distinct γ-secretase variants. We speculate that extrinsic components, in combination with core complexes, may tailor functional variants of this enzyme to their preferred substrates.
Substance P inhibits progesterone conversion to neuroactive metabolites in spinal sensory circuit: A potential component of nociception
Authors: Patte-Mensah Christine , Kibaly Cherkaouia , Mensah-Nyagan Ayikoe G.
Published: June 2005

A crucial biochemical reaction in vertebrates is progesterone conversion into neuroactive metabolites such as dihydroprogesterone (5α-DHP) and tetrahydroprogesterone (3α,5α-THP), which regulate several neurobiological processes, including stress, depression, neuroprotection, and analgesia. 3α,5α-THP is a potent stimulator of type A receptors of GABA, the main inhibitory neurotransmitter. Here, we show that in the spinal sensory circuit progesterone conversion into 5α-DHP and 3α,5α-THP is inhibited dose-dependently by substance P (SP), a major mediator of painful signals. We developed a triple-labeling approach coupled with multichannel confocal microscope analysis, which revealed that, in the spinal cord (SC), SP-releasing afferents project on sensory neurons expressing simultaneously neurokinin 1 receptors (rNK1) and key enzymes catalyzing progesterone metabolism. Evidence for a potent inhibitory effect of SP on 5α-DHP and 3α,5α-THP formation in the SC was provided by combining pulse–chase experiments using [
3
H]progesterone as precursor, HPLC, recrystallization of [
3
H]metabolites to constant specific activity, and continuous flow detection of radioactive steroids. The action of SP on progesterone metabolism was mimicked by the rNK1-specific agonist [Sar-9,Met(O
2
)
11
]-SP. The selective rNK1 antagonist SR140333 totally reversed the effect of SP on progesterone conversion into 5α-DHP and 3α,5α-THP. These results provide direct evidence for the occurrence of anatomical and functional interactions between the SP-rNK1 system and neuroactive steroid-producing cells in the SC. The data suggest that, through the local control of 3α,5α-THP concentration in spinal sensory circuit, the SP-rNK1 system may indirectly interfere with GABA
A
receptor activity in the modulation of nociceptive transmission.
The feeding of sledge dogs on Antarctic expeditions
Authors: Orr N. W. M.
Published: June 2005

1. The diets of sledge dogs at a British Antarctic sledging base were studied both at base and during sledge journeys, and samples of the diets and the relevant faeces were analysed. Changes in weight were related to calorie intakes.

2. The calorific requirements of sledge dogs were found to vary considerably from dog to dog and depended on the activity in which the dogs were involved. Whereas 2500 kcal/dog daily were just sufficient to maintain the body-weight of a completely idle dog, 5000 kcal/dog were insufficient to maintain the body-weight of a dog pulling a heavy sledge over long distances.

3. Seal meat was found to be the most beneficial and most satisfactorily absorbed diet. The artificial diets, pemmican and Nutrican, were adequate to maintain body-weight if sufficient supplies were available to give dogs as much as twice the routine ration, but were uneconomical in that large quantities of nutrients were passed in the faeces.
A study of chewing during eating in the cow
Authors: Gill J. , Campling R. C. , Westgarth D. R.
Published: June 2005

1. A preliminary study was made of chewing duringeating with a total of sixcows with rumen fistulas, given diets of hay or herbage. A sieving technique was used to determine the size of particles of food swallowed at intervals throughout the eating period. The number of jaw movements, number and weight of the swallowed food boluses and the time spent eating were measured with each diet.

2. The mean particle size of hay contained in a bolus collected at the cardia varied between individual cows from 1602 μm to 1244 μm. Boluses swallowed in the first few minutes of eating contained particles of a larger average size than those at any other time during the meal. Also, the rate of swallowing boluses of food was much faster at the beginning of a meal and the weight of boluses smaller than at any other time. The frequency of jaw movements did not vary appreciably during a meal.

3. Increasing the amount of hay given to the cows by 50 % or giving a different hay did not cause any significarlt alteration in the average size of particles of swallowed hay, and changes in the rate of swallowing boluses, or in, the rate of jaw movements and the size of boluses were not very marked.

4. With a diet of herbage, boluses were swallowed rapidly and the average particle size of swallowed food was larger than that of hay. Also, there were slightly more jaw movements per min and larger boluses than with hay.

5. The observations made in the study are discussed in relation to possible factors that determine the particle size of swallowed food.
A study in the rat of the interaction between the effects of calcium and phosphorus content of the diet at two different levels and the presence or absence of vitamin D
Authors: Harrand R. B. , Green R. M. , Hartles R. L.
Published: June 2005

1. Four groups of weanling rats were maintained on diets containing either 0.12% or 0.24% of both calcium and phosphorus, in the presence and absence of added ergocalciferol. 2. Increase in mineral intake or the provision of vitamin D increased the final body-weight, with a significant interaction between the two factors. 3. Serum Ca and P concentrations were raised significantly by both the vitamin and the increase in mineral intake without signi ficant interaction. 4. Measurements were made of bone and tooth weights and ash values and of the length of the humeri. For only two measurements was there any interaction between the effect of vitamin D and increase in mineral intake, namely the length of the humeri, and their ash values expressed as a percentage of the dry fat-free weight. 5. It is concluded that in relation to the amount of mineral deposited, the incisor tooth is more resistant to nutritional stress than is the bone.
The effect of diet on the compositions of the triglycerides and unesterified fatty acids isolated from the plasma, liver and adipose tissues of rabbits
Authors: Moore J. H. , Williams D. L.
Published: June 2005

1. Groups of male rabbits (ten to thirteen per group survived) were givenad lib. a diet consisting of 80 parts of a low-fat basal diet to which were added: for group I, 20 parts maize oil; for group 2, 20 parts butterfat; for group 3, 10parts maize oil and and 10parts butter- fat; for group 4, 0.47 parts maize oil and 43.1 parts wheat starch; and for group 5, 10.2parts maize oil and 21.6 parts wheat starch. The animals in group 6 were givenan ordinary com- mercial rabbit diet. 2. The rabbits were given the various diets for 38 weeks, after which a sample of blood was taken. The rabbits were then killed and the liver and a sample of perine- phric adipose tissue were removed from each animal. The plasma, liver and adipose tissue lipids werefractionated on columns of Florisil and the fatty acid compositions of the tri- glyceride and unesterified fatty acid fractions were determined by gas-liquid chromatography.

3. The effects of the different diets on the composition of the unesterifiedfatty acids in the plasma were very similar to the effects of the diets on the fatty acid composition of the plasma triglycerides, but in the plasma unesterified fatty acids the concentration of stearic acid was consistently higher and the concentration of linoleic acid was consistently lower than in the plasma triglycerides. 4. There appeared to be a positive rectilinear relationship between the concentration of stearic acid in the plasma triglycerides and the concentration of triglycerides in the plasma. 5. In the triglycerides of the plasma, the concentrations of palmitic and stearic acids were consistently greater and the concentration of linoleic acid was consistently less than the corresponding concentrations of these fatty acids in the triglycerides of the adipose tissues. In the two groups of rabbits given low-fat diets the fatty acid composition of the liver trigly- cerides was almost identical with that of the plasma triglycerides. 6. In each of the six groups of rabbits the composition of the unesterified fatty acids in the plasma was identical with that of the unesterified fatty acids in the adipose tissues. Inthe unesterified fatty acids of the liver the concentrations of linoleic andarachidonic acids were consistently greater and the concentrations of myristic, palmitic and palmitoleic acids were consistently less than the corresponding concentrations of these acids in the unesterified fatty acids of the plasma and adipose tissues. 7. The results of this investigation are discussedin the light of recent con-cepts on the metabolic relationships between the unesterified fatty acids and triglycerides of the liver, plasma and adipose tissues.
The fasting metabolism of cattle
Authors: Blaxter K. L. , Wainman F. W.
Published: June 2005

1. The metabolism of seventeen steers was determined on forty-nine occasions during fasts of either 112 or 136 h duration.

2. Faeces continued to be produced during fasts of up to 136 h duration at rates which were 15–20% of those noted before the fasts began.

3. Carbon dioxide production and oxygen consumption fell continuously throughout with animals weighing less than 200 kg but changed little after 88 h in animals weighing more than 200 kg. Methane production was considerably reduced during fasting but did not disappear. Urinary nitrogen excretion changed very little. Of the total loss of energy from the body, the loss of protein accounted for 25%. This was unaffected by age or size of animal.

4. With individual Ayrshire steers, metabolism increased during growth with body-weight raised to the power 0.68±0.05. No greater precision of estimate was obtained from logarithmic regressions of metabolism on body-weight than from linear ones.

5. Seven Ayrshire steers had a mean fasting metabolism of 100±1.6 kcal/kg W0.73 24 h, eight Black cattle of the Aberdeen Angus type a fasting metabolism of 81±1.5 kcal/kg W0.73 24 h and two Ayrshire x Beef Shorthorn steers a fasting metabolism of 96±2.9 kcal/kg W0.73 24 h. Variation in the fasting metabolism of an individual steer from time to time, expressed as a coefficient of variation, was ±7.4%.

6. The results are discussed in relation to interspecies generalizations about the relation between fasting metabolism and body-weight.
Simultaneous measurements of the rates of production of acetic, propionic and butyric acids in the rumen of sheep on different diets and the correlation between production rates and concentrations of these acids in the rumen
Authors: Leng R. A. , Brett D. J.
Published: June 2005

1. A technique using a constant infusion of [ U-14C]acetate, [U-14C]propionate and [2–3-T]– hutyrate has been developed to measure simultaneously the production rates of acetic, propionic and hutyric acids in the rumen of sheep. 2. Infusions of 14C-lahelled acids suggested that interconversions of acetic acid or hutyric acid with propionic acid and vice versa were small in extent, hut the conversion of acetic acid into butyric acid accounted for between 40 and 50% of the butyric acid produced. The conversion of hutyric acid into acetic acid accounted for 6–13% of the acetic acid produced in the rumen. 3. The production rates and the concentrations of individual acids in the rumen were simply related. 4. The difference between measured production rate and the rates of conversion of one acid into the other two acids for acctic, propionic and butyric acids, were 85–91%, 91–100% and 53–73% of the measured production rates respectively.
Effects of dietary fish oil on the composition and stability of turkey depot fat
Authors: Neudoerffer T. S. , Lea C. H.
Published: June 2005

1. Beef fat (2.5%) and anchovy oil (2.5%; 2.5% plus 0.02% ethoxyquin; 5%) were incorporated into isocaloric cereal-based diets A, B, C and D and given to turkeys from 2 to 10 weeks of age. Diets A, B, and C contained 13 and diet D 26 i.u. α-tocopheryl acetate/kg. The lipids of diets B and D, which contained fish oil without ethoxyquin, autoxidized in the feeding troughs, but not seriously in the brief period of exposure permitted. 2. The birds all remained healthy and grew well, the only nutritional effects of the fish oil being a depressed storage of vitamin A in the liver at both levels of feeding (prevented by ethoxyquin) and a slightly adverse effect, at the higher level only, on food conversion ratio. 3. The skin fats of the birds given fish oil contained seven major and two minor fatty acids, derived from the fish oil, which were not present in the skin of the control group given beef fat, as well as one major fish oil acid present in much greater concentration in the birds given fish oil than in the controls. All these acids were present in the skin fats at about half or two-thirds of their concentrations in the dietary lipid, except for acid 22:5, which reached two or three times this level. 4. The stabilities towards autoxidation of the skin fats decreased in the order A > C > B > D, as their content of polyunsaturated fatty acids increased, but the greater stability of group C as compared with B was probably due, in the main, to the higher tocopherol content of the skin fat of the birds on the ethoxyquin-containing diet. Fishy flavours which developed on cooking showed a similar relationship to diet.
Studies on magnesium in ruminant nutrition
Authors: Suttle N. F. , Field A. C.
Published: June 2005

1. In Expt 1 balance studies were carried out with six wether sheep receiving chopped hay and concentrates and given, 0, 5, or 101. water/day by intraruminal infusion. Allocation to two 3 x 3 latin squares was arranged to allow calculation of main treatment and residual effects.

2. Infusing 101.water/day increased the total daily urinary output of magnesium, phosphorus and sodium by 31, 45 and 100% (P<0.05). Faecal losses of Mg, and P tended to decrease correspondingly and with both elements retention remained positive but retention of Na became negative (P < 0.05). 3. Residual effects were not detected, and infusing 5 1. water/ day generally produced intermediate and non-significant effects. 4. When pellets made from dried, ground, young spring pasture or ccncentrates rich in Mg were included in the diet of four wethers in Expts 2 and 3, infusions of 101. water/day produced much greater decrcases in faecal losses and retentions of Na and K and greater increases in the urinary excretion of those elements than those found in Expt I. Effects on Mg, P and Ca balance were similar to those in the main experiment. 5. The biological significance of these results and relationships between the observed effects and the aetiology of hypomagnesaemic tetany are discussed.
A separation of the direct toxic effects of dietary raw egg white powder from its action in producing biotin deficiency
Authors: Peters J. M.
Published: June 2005

1. Young adult female albino rats were given 20, 40, 60, 80, and 100% raw egg white powder in their diet; controls were fed on laboratory chow. Daily clinical measurements were made for 2 weeks. The rats were then killed, and the weights and water contents of various organs were determined.

2. The experiment was repeated with groups of young male albino rats fed for 2 and 4 weeks.

3. Toxic signs caused by increasing intake of dried raw egg white powder were: decreased food intake, weight loss, soft stool, diarrhoea, glycosuria and death. Water intake and urine output rose with increasing raw egg white powder in the diet. In all groups the urine was alkaline and the urinary output of protein increased. At autopsy there was a decrease in the absolute weight and in the water content of most body organs with increasing amounts of raw egg white powder in the diet.

4. The toxicity syndrome was not prevented by a biotin supplement, but was largely prevented by heat denaturation of the egg white powder; 80% of denatured egg white was well tolerated, as was 80% of casein in the diet.

5. The syndrome was due to the direct toxic effects of large amounts of dietary raw egg white powder and not to biotin deficiency.
Incubation inside the bovine rumen
Authors: Czerkawski J. W.
Published: June 2005

1. Details are given for the construction and use of an apparatus for the incubation of rumen liquor in semi-permeable sacs inside the bovine rumen. It was found practicable, using one animal, to incubate simultaneously samples of strained diluted rumen liquor in three identical vessels, each of 100–120 ml capacity, for periods of up to 23 h.

2. The optimal conditions for experiments of this type were investigated. It was shown that, under the conditions used, the pH value of the reaction mixtures varied little compared with the pH changes that occurred inside the rumen, and that the sampling technique was satisfactory.

3. The effects of the size and type of inoculum were also investigated. The microbial growth, measured by increases in turbidity and in concentration of protein, was greatest when the rumen liquor inoculum constituted about 20% of the reaction mixture and when the protozoa and large food particles were removed.

4. The apparatus was used to study microbial growth and hydrogenation of fatty acids in rumen liquor.
The nutritional value of poor proteins fed at high levels
Authors: Anantharaman K. , Carpenter K. J. , Nesheim M. C.
Published: June 2005

1. The same six high-protein diets that were fed to rats (Carpenter & Anantharaman, 1968) have now been fed to chicks.

2. The net nitrogen retention by chicks, per 100 kcal consumed, was for each diet greater by 20–50% than the retention by rats. For a diet based on a mixture of commercial protein concentrates the NDpCal % was 19·1 (± 0·18); this value greatly exceeded the theoretical maximum of 14·6 obtained from the equations of Miller & Payne (1963).

3. Although groundnut protein plus lysine has a calculated chemical score of only 56, chicks receiving this at a high level retained N at the same rate (NDpCal % of 17·5–17·9) as those receiving a diet which included egg protein at the level (26% of the dietary ME) predicted to be optimal for them.

4. The ‘endogenous + metabolic’ losses of N were in almost the same proportion to metabolic size for chicks as for rats.