Utilization of milk energy by suckling mink kits

A total of 36 mink dams and their litters of 3, 6 or 9 kits were used for determination of milk intake of the suckling young by means of deuterium dilution technique, and chemical composition of milk and of kit bodies. Measurements were performed during lactation weeks 1?–?4, each week with 3 dams with each litter size. Milk intake was determined over a 48?h measurement period, and by the end of this milk samples were collected and 2 kits (litters of 6 and 9) or 1 kit per litter (litters of 3) were killed for body chemical composition. Based on the results, different models were applied for calculation of the energetic efficiency of milk. Dam milk yield increased steadily from week 1 until week 3 but only slightly from week 3 to 4. The increase declined with increasing litter size, and for dams suckling 9 kits the increment from week 3 to week 4 was only 2?g. The dry matter content of milk increased significantly as lactation progressed, being reflected in crude protein increasing from 6.9% in lactation week 1 to 8.1% in week 4. Milk fat increased concomitantly from 5.6% to 8.0%. In kit bodies, crude protein content increased from 9.4% in week 1 to about 12% in weeks 3 and 4. Body fat content increased from week 1 (4.1%) to week 3 (8.4%) and then declined in week 4 (7.1%). Animals suckled in litters of 3 kits had the highest milk intake and live weight and kits suckled in litters of 9 had the lowest milk intake, live weight and daily gain. In terms of milk intake per g gain kits in litters of 6 were the most efficient, with 4.1?g milk per g body gain. The metabolizable energy requirement for maintenance (MEm) was estimated to 448 kJ/kg^0.75 and the efficiency of utilization of ME for body gain (k_g) to 0.67, the estimates being higher (MEm) or in good agreement with previous findings (k_g) in suckling mink kits.     

Exceptional carbon uptake in European forests during the warm spring of 2007: a data–model analysis

Temperate and boreal forests undergo drastic functional changes in the springtime, shifting within a few weeks from net carbon (C) sources to net C sinks. Most of these changes are mediated by temperature. The autumn 2006–winter 2007 record warm period was followed by an exceptionally warm spring in Europe, making spring 2007 a good candidate for advances in the onset of the photosynthetically active period. An analysis of a decade of eddy covariance data from six European forests stands, which encompass a wide range of functional types (broadleaf evergreen, broadleaf deciduous, needleleaf evergreen) and a wide latitudinal band (from 44° to 62°N), revealed exceptional fluxes during spring 2007. Gross primary productivity (GPP) of spring 2007 was the maximum recorded in the decade examined for all sites but a Mediterranean evergreen forest (with a +40 to +130 gC m^?2 anomaly compared with the decadal mean over the January–May period). Total ecosystem respiration (TER) was also promoted during spring 2007, though less anomalous than GPP (with a +17 to +93 gC m^?2 anomaly over 5 months), leading to higher net uptake than the long‐term mean at all sites (+12 to +79 gC m^?2 anomaly over 5 months). A correlative analysis relating springtime C fluxes to simple phenological indices suggested spring C uptake and temperatures to be related. The CASTANEA process‐based model was used to disentangle the seasonality of climatic drivers (incoming radiation, air and soil temperatures) and biological drivers (canopy dynamics, thermal acclimation of photosynthesis to low temperatures) on spring C fluxes along the latitudinal gradient. A sensitivity analysis of model simulations evidenced the roles of (i) an exceptional early budburst combined with elevated air temperature in deciduous sites, and (ii) an early relief of winter thermal acclimation in coniferous sites for the promotion of 2007 spring assimilation.     

Understanding Fluctuations in Bobcat Harvest at the Northern Limit of Their Range

ABSTRACT In Quebec, Canada, harvest of bobcats (Lynx rufus) started to decline in 1985 and by 1991, harvest seasons were closed due to concerns of a perceived population decline. Since the closing of harvest season in 1991, the average temperature has increased, snow quantity has decreased, and important changes in agriculture and forest management have occurred. In light of changing conditions, the situation of Quebec bobcats needed reassessment. Thus, we analyzed harvest data to clarify the current status of bobcat populations in Quebec. From 1980 to 1991, bobcat harvest in Quebec was strongly correlated with bobcat harvest in Maine (USA), Nova Scotia (Canada), Ontario (Canada), and Vermont (USA). Extrapolations of harvest in Quebec relative to harvest in Maine, Ontario, Vermont, and Nova Scotia suggested an increase in number of bobcats after 1991. Mass of male and female bobcats before 1991 was less than mass of animals captured after 1991. Percentage of juveniles in the reported harvest before 1991 was higher than after 1991. However, percentage of males and litter sizes in the harvest did not differ before and after 1991. The geographic distribution of bobcats captured has gradually expanded after the closure of the harvest season. Our findings suggest that bobcat populations in Quebec have recovered from the 1985–1991 decline, and that the harvest season for this species could resume. This study also illustrates how managers can rely on data from neighboring jurisdiction to manage species when local harvest data is unavailable.     

High Humidity Leads to Loss of Infectious Influenza Virus from Simulated Coughs

Background

The role of relative humidity in the aerosol transmission of influenza was examined in a simulated examination room containing coughing and breathing manikins.

Methods

Nebulized influenza was coughed into the examination room and Bioaerosol samplers collected size-fractionated aerosols (<1 µM, 1–4 µM, and >4 µM aerodynamic diameters) adjacent to the breathing manikin’s mouth and also at other locations within the room. At constant temperature, the RH was varied from 7–73% and infectivity was assessed by the viral plaque assay.

Results

Total virus collected for 60 minutes retained 70.6–77.3% infectivity at relative humidity ≤23% but only 14.6–22.2% at relative humidity ≥43%. Analysis of the individual aerosol fractions showed a similar loss in infectivity among the fractions. Time interval analysis showed that most of the loss in infectivity within each aerosol fraction occurred 0–15 minutes after coughing. Thereafter, losses in infectivity continued up to 5 hours after coughing, however, the rate of decline at 45% relative humidity was not statistically different than that at 20% regardless of the aerosol fraction analyzed.

Conclusion

At low relative humidity, influenza retains maximal infectivity and inactivation of the virus at higher relative humidity occurs rapidly after coughing. Although virus carried on aerosol particles <4 µM have the potential for remaining suspended in air currents longer and traveling further distances than those on larger particles, their rapid inactivation at high humidity tempers this concern. Maintaining indoor relative humidity >40% will significantly reduce the infectivity of aerosolized virus.     

New replication mutant pnh602 and its relationship to plasmid pAS3, another deletion derivative of plasmid R6K

A stable deletion derivative pNH602 was obtained when the recently described higher-copy-number point mutant pNH601 of plasmid R6K was introduced to a minicells-producing strain of Escherichia coli. The size of plasmid pNH602 is 18.8 Mg/mol as determined by electron microscopy. The 7.2 Mg/mol fragment of R6K genome missing in pNH602 carries the Smr-determinant and the region finO and, according to the results of restriction analysis, it includes one EcoRI site. With its radioisotopically determined 33 copies of pNH602 per E. coli K-12 chromosome (npc), representing a 23% increase of the point mutant pNH601 and 150% enhancement of R6K npc, plasmid pNH602 differs from another closely related R6K deletion derivative pAS3 of the same size which exhibits only 20 npc. Both pNH602 and pAS3 plasmids are conjugative.     

Optimal baker's yeast production in extended fed-batch culture by using a computer coupled pilot fermenter

Summary The aim of this survey is to show the feasibility of the extended fed-batch culture of Saccharomyces cerevisiae conducted by computer . The adopted control parameter is the oxygen uptake rate ; measurement of the respiratory quotient determines operation of the carbon substrate feed pump.     

Palaeohistology of the bones of pterosaurs (Reptilia: Archosauria): anatomy, ontogeny, and biomechanical implications

Thin sections from long bones of specimens representing pterosaurs ranging from the Early Jurassic to the latest Cretaceous provide a profile of bone histology across a range of sizes, skeletal elements, growth stages, and phylogenetic positions. Most pterosaur bone is fibro-lamellar, organized in an unusual way that suggests high growth rates through ontogeny. Fibro-lamellar deposits are finished by a relatively abrupt deceleration or cessation of growth represented by lamellar, poorly vascularized subperiosteal bone in what appear to be adults. Pterosaurs had the thinnest bone walls of any tetrapods; they complemented high rates of periosteal deposition with almost equally high rates of endosteal erosion. Pterosaurs show a great variety of histologic features that include articular calcified cartilage, sub-chondral bone plates, trabecular bone struts and related internal supports, and secondary deposition and remodeling of bone. They remodeled their bones internally by (1) depositing endosteal bone coatings on the inner cortex and over struts of pre-existing internal bone, (2) secondarily filling bone spaces, and (3) Haversian reworking. The construction of these struts reflects both developmental patterns of bone construction and biomechanical function. Alternating plywood-like layers of bone, heretofore undescribed in tetrapods, provided strength, as did the obliquely oriented system of reticular blood vessels in the bones. The distribution and ontogenetic features of pterosaur bone tissues, when combined with other evidence, suggest generally high growth rates, high metabolic levels, altricial birth, and extended parental care.     

Analysis of amino acid requirements ofClostridium thermocellum

Summary Clostridium thermocellum is a species able to convert cellulose to ethanol on complex medium. A systematic study of changes in the concentration of amino acids in the medium during growth of the bacterium has permitted us to obtain a chemically defined medium more effective than that hitherto used and to obtain some information about the use of amino acids by this bacterium.