Informing conservation by identifying range shift patterns across breeding habitats and migration strategies

A species distribution combines the resources and climatic tolerances that allow an individual or population to persist. As these conditions change, one mechanism to maintain favorable resources is for an organism to shift its range. Much of the research examining range shifts has focused on dynamic distribution boundaries wheras the role of species breeding habitat or migration strategies on shift tendencies has received less attention. We expand on previous research by using a large suite of avian species (i.e., 277), analyzing observed abundance-weighted average latitudes, and categorizing species by breeding environment and migration strategy. We used the North American Breeding Bird Survey dataset to address two questions: (1) Has the center of observed abundance for individual species shifted latitudinally? (2) Is there a relationship between migration strategy or breeding habitat and range shifts? Results indicate the majority of species have experienced poleward range shifts over the last 43 years, and birds breeding in all habitat showed trends of poleward shift but only those species breeding in scrub-shrub and grassland environments were different from zero. Additionally, species that are short distance migrants are experiencing significant poleward shifts while Neotropical and permanent residents had shifts that were not different from zero. Our findings do support the general trend expected from climate driven changes (i.e., > 52 % shifting poleward), however, the proportion of species exhibiting equatorial shifts (24 %) or no significant shifts (23 %) illustrates the complex interplay between land cover, climate, species interactions, and other forces that can interact to influence breeding ranges over time. Regardless of the mechanisms driving range shifts, our findings emphasize the need for connecting and expanding habitats for those species experiencing range shifts. This research describes the patterns of breeding birds through central North America and we encourage future research to focus on the mechanisms driving these patterns.     

Lack of response to all-trans retinoic acid supplementation in adult dogs following left pneumonectomy.

We showed previously that removing 55-58% of the lung by right pneumonectomy (R-PNX) in adult dogs triggers compensatory growth of the remaining lung, but removing 42-45% of the lung by left PNX (L-PNX) does not. We also showed that, following R-PNX, supplemental all-trans retinoic acid (RA) selectively enhances alveolar capillary endothelial cell volume (Yan X, Bellotto DJ, Foster DJ, Johnson RL, Jr., Hagler HH, Estrera AS, and Hsia CC. J Appl Physiol 96: 1080-1089, 2004). We hypothesized that RA supplementation might enhance compensation following L-PNX and tested this hypothesis by administering RA (2 mg.kg(-1).day(-1), 4 days/wk) or placebo orally to litter-matched adult foxhounds for 4 mo following L-PNX. Resting lung function was measured under anesthesia. Air and tissue volumes of the remaining lung were assessed by high-resolution computed tomography scan and by detailed postmortem morphometric analysis of the fixed lung. There was no significant difference in resting lung function, lung volume, alveolar structure, or septal ultrastructure between RA and placebo treatment groups. We conclude that RA supplementation does not induce post-PNX compensatory lung growth in the absence of existing cellular growth activities initiated by other primary signals.     

Molecular cloning of the Clostridium botulinum structural gene encoding the type B neurotoxin and determination of its entire nucleotide sequence.

DNA fragments derived from the Clostridium botulinum type A neurotoxin (BoNT/A) gene (botA) were used in DNA-DNA hybridization reactions to derive a restriction map of the region of the C. botulinum type B strain Danish chromosome encoding botB. As the one probe encoded part of the BoNT/A heavy (H) chain and the other encoded part of the light (L) chain, the position and orientation of botB relative to this map were established. The temperature at which hybridization occurred indicated that a higher degree of DNA homology occurred between the two genes in the H-chain-encoding region. By using the derived restriction map data, a 2.1-kb BglII-XbaI fragment encoding the entire BoNT/B L chain and 108 amino acids of the H chain was cloned and characterized by nucleotide sequencing. A contiguous 1.8-kb XbaI fragment encoding a further 623 amino acids of the H chain was also cloned. The 3' end of the gene was obtained by cloning a 1.6-kb fragment amplified from genomic DNA by inverse polymerase chain reaction. Translation of the nucleotide sequence derived from all three clones demonstrated that BoNT/B was composed of 1,291 amino acids. Comparative alignment of its sequence with all currently characterized BoNTs (A, C, D, and E) and tetanus toxin (TeTx) showed that a wide variation in percent homology occurred dependent on which component of the dichain was compared. Thus, the L chain of BoNT/B exhibits the greatest degree of homology (50% identity) with the TeTx L chain, whereas its H chain is most homologous (48% identity) with the BoNT/A H chain. Overall, the six neurotoxins were shown to be composed of highly conserved amino acid domains interceded with amino acid tracts exhibiting little overall similarity. In total, 68 amino acids of an average of 442 are absolutely conserved between L chains and 110 of 845 amino acids are conserved between H chains. Conservation of Trp residues (one in the L chain and nine in the H chain) was particularly striking. The most divergent region corresponds to the extreme carboxy terminus of each toxin, which may reflect differences in specificity of binding to neurone acceptor sites.     

Affinity chromatography of bovine trypsin. A rapid separation of bovine α- and β-trypsin

Affinity adsorbents for bovine trypsin were prepared by covalently coupling p-(p′-amino-phenoxypropoxy)benzamidine to cellulose and to agarose. Trypsin binds to both adsorbents at pH6–8 and is released at low pH values or in the presence of n-butylamine hydrochloride. Pure β-trypsin may be eluted from crude trypsin bound at pH8.0 to the cellulose adsorbent by stepwise elution with an acetate buffer, pH5.0. Both α- and β-trypsin may be isolated by chromatography of crude trypsin on the agarose derivative in an acetate buffer, pH4.0. These two methods for purifying the trypsin are specific to the particular adsorbents. They are rapid and convenient in use. Both methods leave a mixture of the two enzymes bound to the adsorbent and release occurs only at low pH values. The effects of pH, composition and ionic strength of buffer and other variables on both purification methods are described. Affinity adsorbents of soya-bean trypsin inhibitor and of N-α-(N′-methyl-N′-sulphanilyl) sulphanilylagmatine bound to agarose were prepared, but were found to be of limited usefulness in the purification of trypsin.     

Competitive inhibition of human skin collagenase by N-benzyloxycarbonyl-L-prolyl-L-alanyl-3-amino-2-oxopropyl-L-leucyl-L- alanylglycine ethyl ester.

A 'ketomethylene' peptide, N-benzyloxycarbonyl-L-prolyl-L-alanyl-3-amino- 2-oxopropyl-L-leucyl-L-alanylglycine ethyl ester, was synthesized and shown to be a fairly potent competitive inhibitor of human skin collagenase.     

The effects of stanozolol and boldenone undecylenate on scrotal width, testis weight, and sperm production in pony stallions

Fifty mature pony stallions were randomly assigned to one of five treatment groups: Group 1- controls (no treatment), Group 2 - 0.55 mg/kg stanozolol weekly for 13 treatments, Group 3 - 1.1 mg/kg stanozolol every 3 weeks for 5 treatments, Group 4 - 1.1 mg/kg boldenone undecylenate every 3 weeks for 5 treatments, and Group 5 - 0.55 mg/kg boldenone undecylenate weekly for 13 treatments. Scrotal widths (SW), combined testis weights (CTW), and daily sperm productions (DSP) were not different between Groups 1 and 2. Ponies in Group 5 had smaller SW (P<0.01), smaller CTW and decreased DSP compared to controls (P < 0.05). Although SW for ponies in Groups 3 and 4 were less than for controls (P < 0.01), CTW and DSP were not different. The only treatment regime that did not alter SW, CTW, and DSP was Group 2 (0.55 mg/kg stanozolol weekly for 13 treatments).     

The kinetics of hydrolysis of some synthetic substrates containing neutral hydrophilic groups by pig pepsin and chicken liver cathepsin D.

1. Several peptides containing either of the sequences -Phe(NO2)-Trp- and -Phe(NO2)-Phe- and an uncharged hydrophilic group were synthesized, and the steady-state kinetics of their hydrolysis by pig pepsin (EC 3.4.23.1) and chicken liver cathepsin D (EC 3.4.23.5) were determined. Despite the presence of a hydrophilic group to increase substrate solubility, it was not possible to achieve the condition [S]0 much greater than Km, and, in some cases, only values of kcat./Km could be determined by measuring the first-order rate constant when [S]0 much less than Km. 2. Occupancy of the P2 and P3 sites considerably enhanced the specificity constant, and alanine was more effective than glycine at site P2. 3. The specificity constants for the hydrolysis by pepsin of those substrates in the present series that contain an amino acid residue at site P3 are considerably lower than for comparable substrates containing a cationic group. This difference does not apply to cathepsin D. 4. Hydrolyses with cathepsin D commonly exhibited a lag phase, and a possible explanation for this is given.     

Polymorphonuclear leukocyte migration through human amnion membrane

A new in vitro model has been developed for studying migration of human polymorphonuclear leukocytes (PMN) through living native cellular and matrix barriers. Human amnion membrane consists of a single layer of epithelium bound to a continuous basement membrane interfacing an avascular collagenous stroma. Living amnion was placed in plastic chambers with separate compartments on each side of the membrane. PMN were introduced on the epithelial side of the amnion, and a Millipore filter (Millipore Corp., Bedford, Mass.) was placed against the stromal side. In response to N-formylmethionyl-leucyl- phenylanlanine (FMLP) chemoattractant, PMN penetrated the full thickness of the amnion and were collected and counted on the filter. The rate of PMN traversal of the amnion was dependent on the concentration of FMLP (optimal at 10(-8)M) as well as the slope of the FMLP gradient across the amnion. The route of PMN migration was studied by transmission electron microscopy. PMN first attached to the epithelial surface, then infiltrated between intercellular junctions. PMN migrated around or through tight junction and hemidesmosome attachments. The PMN then penetrated the basement membrane and migrated through the dense collagenous stroma. The present amnion migration system has characteristics of the in vivo inflammatory state not described in any previous method for monitoring PMN migration in vitro. Prior methods have not used native epithelium, whole basement membrane, or collagenous stroma. PMN penetration of these barriers occurs in the normal inflammatory response and probably involves biochemical mechanisms not required for simple migration through the pores of an artificial filter. The amnion system can be useful for future biochemical and morphological studies of PMN penetration of these barriers and possible repair processes that may follow.     

Luteinizing hormone response to estradiol benzoate in cows postpartum and cows with ovarian cysts

Twenty-seven dairy cows were evenly assigned to one of three groups and given an intramuscular injection of 2 mg estradiol benzoate. Cows in group 1 were greater than 30 days postpartum at treatment and had been diagnosed via rectal palpation to have ovarian cysts. Cows in groups 2 and 3 were 12 to 14 and 30 to 40 days postpartum, respectively. Blood plasma was collected from all cows before treatment and then every three hours for 36 hours post-treatment. Concentrations of LH, estradiol-17 beta and progesterone in plasma were determined by radioimmunoassay. Four, zero and five cows in groups 1, 2 and 3, respectively, had concentrations of progesterone greater than 1.0 ng/ml before estradiol benzoate treatment. None of these cows had a peak LH release greater than 5 ng/ml following estradiol benzoate treatment. The numbers of cows with progesterone concentrations less than 1 ng/ml that released LH (>5 ng/ml) in response to estradiol benzoate were 3 of 5, 3 of 9, and 4 of 4 for groups 1, 2, and 3, respectively; the proportion for group 3 was higher (P<.05) than for group 2. Of the cows that released LH, mean peak LH concentrations were 33.3+/-5.4, 14.8+/-7.2 and 24.6+/-9.8 ng/ml for groups 1, 2 and 3, respectively, and the duration of the LH increase was 8.0+/-1.0, 8.0+/-2.0 and 13.0+/-4.0 hours. The time from estradiol benzoate treatment to peak LH release for cows with ovarian cysts (25+/-2 hours) was delayed (P<.05) compared with that for cows 30 to 40 days postpartum without ovarian cysts (16+/-1 hour). In summary, responsiveness to estradiol benzoate is regained between 2 to 4 weeks postpartum in most cows. In addition, some cows with ovarian cysts can release LH in response to estradiol benzoate, but peak LH release is delayed compared to cows at a comparable stage postpartum without ovarian cysts.