Humoral immune responses to Mycoplasma hyopneumoniae in sows and offspring following an outbreak of mycoplasmosis

Previously healthy sows, seropositive to Mycoplasma hyopneumoniae, developed clinical signs of mycoplasmosis, as well as increasing amounts of antibodies to M. hyopneumoniae during an outbreak of the disease in a herd. During the early phase of the outbreak, young piglets (2 weeks) with maternal antibodies remained healthy while older seronegative piglets (4–7 weeks) developed the disease. The duration of the maternal antibodies to M. hyopneumoniae varied between litters and was related to the amount of antibodies in the serum of the dam. In sows, the level of serum antibodies decreased continuously from 4 weeks ante partum to partus, and the level of antibodies in the whey of colostrum was comparable to that in serum 4 weeks ante partum. After loss of maternal antibodies to M. hyopneumoniae, seropositive animals were not found among piglets younger than 9 weeks. Therefore peripheral blood mononuclear cells (PBMC) were collected from various age categories of piglets in order to measure the ability to produce antibodies to M. hyopneumoniae in vitro. PBMC obtained from piglets aged 1 and 3 weeks produced few antibodies to M. hyopneumoniae. Significantly higher levels of antibodies to M. hyopneumoniae were produced by PBMC obtained from pigs aged 5–9 weeks. Thus, the ability of PBMC to produce antibodies to M. hyopneumoniae in vitro seemed to be age-dependent.     

Regional modeling of grassland biogeochemistry using GIS

We used an ecosystem coupled to a Geographic Information System (GIS) to simulate spatial variability in storage and fluxes of C and N within grassland ecosystems. The GIS contained information on driving variables required to run the model. These were soil texture, monthly precipitation and monthly minimum and maximum temperatures. We overlayed polygon maps of the above variables to produce a driving variable map of our study region. The final map had 768 polygons in 160 unique classes. The ecosystem model was run to a steady state for each class and NPP, soil organic matter (SOM), net N mineralization and trace gas emission were mapped back into the GIS for display. Variation in all of the above propertiees occurred within the region. NPP was primarily controlled by climate and patterns followed spatial variation in precipitation closely. Soil organic matter, in contrast, was controlled largely by soil texture within this climatic range. Error associated with aggregation within the study area showed that spatial averages over the study area could be used to drive simulations of NPP, which is linearly related to rainfall. More spatial detail had to be preserved for accurate simulation of SOM, which is nonlinearly related to texture. Mechanistic regional models form a valuable link between process studies and global models.     

Spatial patterns of lacustrine fish assemblages in a catchment of the Mississippi Alluvial Valley

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In vitro selection and characterization of putative probiotics isolated from the gut of Acipenser baerii (Brandt, 1869)

To select and characterize potential probiotic bacteria from the gut microbiota of Siberian sturgeon (Acipenser baerii), 129 strains isolated from the hindgut were screened for antagonistic activity against five fish pathogens. Ten isolates showed antagonism towards three or more pathogens. Nine of these isolates were Gram‐positive, belonging to Lactococcus (seven) and Bacillus (two), and a single strain belonging to the Gram‐negative Citrobacter. These inhibitory isolates were identified using genetic, phentotypic and biochemical traits, and further characterized by in vitro tests assessing the adhesion and growth in mucus and resistance to gastric and intestinal fluids. The candidate probiotics were determined to be non‐pathogenic through an in vivo study. Based on these assays, Lactococcus lactis ssp. lactis STG45 and STG81 showed the broadest inhibitory potential, a high viability in simulated gastrointestinal juice and the highest adhesion capacity to mucus. They were therefore selected as the most promising candidate probiotics. This is the first study screening probiotics among the gut microflora of Siberian sturgeon.     

Use of a tilapia skin xenograft for management of a large bite wound in a dog

A 13-year-old neutered male miniature dachshund suffered ~30% total skin loss following an attack by another dog. After numerous failed attempts at wound management and closure, the wound was successfully healed by epithelialization using tilapia skin grafts. At each tilapia skin graft placement, the wound bed appeared pink, clean, and healthy with excellent progression of epithelialization at all edges. With use of the tilapia grafts, epithelialization occurred at a rate of 1.76 mm/day. As a result, the wound reached complete closure by epithelialization with no evidence of wound contracture in 102 days.Key clinical message:Tilapia skin grafts were successfully used for management of a large bite wound in a dog and may promote accelerated epithelialization in full thickness skin wounds.     

Depletion of stored nutrients during fasting in Nile tilapia (Oreochromis niloticus) juveniles

We evaluated growth performance and metabolic responses in Nile tilapia (Oreochromic niloticus) juveniles (30.2 ± 0.9 g) subjected to 1 (F1), 2 (F2), or 3 weeks (F3) of fasting and then refed for 10 weeks (10WR) compared to controls (FC), which were fed for the full 13-week trial. Weight gain and specific growth rate (SGR) during fasting were lower in all treatments compared to the FC. However, during refeeding, feed intake/body mass and SGR increased in F1, F2, and F3, inducing partial compensatory growth. The hepatosomatic index (HSI), visceral fat index (VFI), liver glycogen (LG), and carcass lipid levels dropped in all fasted fish compared to FC (P < 0.05), showing a depletion of stored nutrients such as fat and LG. Along with LG, fat reserves were mobilized during fasting to maintain basal metabolism and survival, but these energy constituents returned to control levels at 10WR, at which time HSI was higher in all refed fish compared to FC. Additionally, the variables VFI, LG, and lipid in carcass increased in all refed fish, equaling those of FC at 10WR. The results showed that, in contrast with other protocols that used smaller tilapia juveniles, the feeding strategies utilized for Nile tilapia juveniles in this study (1 to 3 weeks of fasting and 10WR) were able to induce only partial compensatory growth. It can be concluded that in situations that require complete food restriction in juvenile Nile tilapia (30 g), an acceptable strategy is to limit the period of fasting to 1 week or less to minimize losses and to achieve partial compensatory growth.     

Recovery of N-urea 10 years after application to a Douglas-fir pole stand in coastal British Columbia

The long-term fate of fertilizer N in forest ecosystems is poorly understood even though such information is critical for designing better forest fertilization practices. We studied the distribution and recovery of ¹⁵N (4.934 atom% excess)-labelled fertilizer (applied as urea at 200 kg N ha⁻¹) 10 years after application to a 38–39-year-old Douglas-fir (Pseudotsuga menzeisii (Mirb.) Franco) stand in coastal British Columbia. The urea was applied in the spring (May 1982) or fall (November 1982). Sampling was conducted in October 1992, and we found that after 10 years, there were few differences between the fall and spring fertilizer applications in total N and ¹⁵N distribution within the tree and forest ecosystem. On average total fertilizer-N recovery was 59.4%; about 14.5% of the applied-N was recovered in the trees including coarse roots, with foliage containing 41% of the labelled-N recovered in the aboveground tree biomass. Tissue ¹⁵N remained mobile and could be transferred to new growth. Soil recovery was 39.8%, which had decreased from 57.0% at a previous 1-year sampling, with an average loss of 3.0% per year from the mineral soil and 3.7% from the litter layers. However, it appears that there was little continuing tree uptake. While short-term effects of fall vs. spring urea application were previously reported, there were no long-term effects on either stand productivity or fertilizer use efficiency, suggesting that if fertilization is properly done, timing of fertilization is not a critical issue in terms of maximizing fertilizer use efficiency for the coastal Douglas-fir forest we studied. Our results also highlight the high capacity of this ecosystem to retain externally applied inorganic N over the long-term, the importance of maximizing nitrogen uptake in the first year, and also of the continuing need to develop new approaches to overcome the generally low efficiency of forest N fertilization.     

Delayed sleep phase cases and controls

Background

Delayed sleep phase disorder (DSPD) is a condition in which patients have difficulty falling asleep before the early morning hours and commonly have trouble awakening before late morning or even early afternoon. Several studies have suggested that variations in habitual bedtime are 40–50% heritable.

Methods

We recruited a case series of 205 participants, along with 221 controls (DSPD-C) with normal sleep, roughly matched for age, gender, and ancestry. A representative sample of San Diego adults recruited some years before was already available to confirm the control group. Both DSPD and DSPD-C provided blood or saliva samples for DNA and completed extensive questionnaires about sleep habits, sleep history, family history, sleep quality, morningness-eveningness traits, depression, mania, and seasonality of symptoms. The DSPD group wore wrist actigraphs for a median of 13.2 days. The representative sample collected previously had undergone actigraphic recordings, from which 48 hours of data were generally available.

Results

The DSPD and DSPD-C samples showed almost no overlap on morningness-eveningness scores. DSPD cases went to bed and arose about 3 hours later than the DSPD-C and the representative sample. DSPD cases reported more difficulties with sleep, poorer sleep quality, and more depression, but there was no significant difference in a history of mania. DSPD cases reported more family history of late bedtimes, but female DSPD reported that their fathers' bedtimes were later than the fathers of male DSPD.

Conclusion

These results indicate a DSPD phenotype is familial and associated with unipolar depression.