Ovarian follicular activity and hormonal profile during estrous cycle in cows: the development of 2 versus 3 waves

Most estrous cycles in cows consist of 2 or 3 waves of follicular activity. Waves of ovarian follicular development comprise the growth of dominant follicles some of which become ovulatory and the others are anovulatory. Ovarian follicular activity in cows during estrous cycle was studied with a special reference to follicular waves and the circulating concentrations of estradiol and progesterone. Transrectal ultrasound examination was carried out during 14 interovulatory intervals in 7 cows. Ovarian follicular activity was recorded together with assessment of serum estradiol and progesterone concentrations. Three-wave versus two-wave interovulatory intervals was observed in 71.4% of cows. The 3-wave interovulatory intervals differed from 2-wave intervals in: 1) earlier emergence of the dominant follicles, 2) longer in length, and 3) shorter interval from emergence to ovulation. There was a progressive increase in follicular size and estradiol production during growth phase of each wave. A drop in estradiol concentration was observed during the static phase of dominant anovulatory follicles. The size of the ovulatory follicle was always greater and produced higher estradiol compared with the anovulatory follicle. In conclusion, there was a predominance of 3-wave follicular activity that was associated with an increase in length of interovulatory intervals. A dominant anovulatory follicle during its static phase may initiate the emergence of a subsequent wave. Follicular size and estradiol concentration may have an important role in controlling follicular development and in determining whether an estrous cycle will have 2 or 3-waves.     

Glucosylated N-acetyllactosamine O-antigen chain in the lipopolysaccharide from Helicobacter pylori strain UA861

The O-antigen chain from the lipopolysaccharide of Helicobacter pylori strain UA861 was determined to be composed of an elongated type 2 N - acetyllactosamine backbone, -[-->3)-beta-D-Gal-(1-->4)-beta-D-GlcNAc-(1- ]n-->, with approximately half of the GlcNAc units carrying a terminal alpha-d-Glc residue at the O -6 position. The O-chain of H.pylori UA861 was terminated by a N -acetyllactosamine [beta-D-Gal-(1-->4)-beta-D- GlcNAc] (LacNAc) epitope and did not express terminal Lewis X or Lewis Y blood-group determinants as previously found in other H.pylori strains. The absence of terminal Lewis X and Lewis Y blood-group epitopes and the replacement of Fuc by Glc as a side chain in the O- chain of H.pylori UA861 represents yet another type of lipopolysaccharide structure from H.pylori species. These structural differences in H.pylori lipopolysaccharide molecules carry implications with regard to possible different pathogenic events between strains and respective hosts.      

A comparison of leaf physiology and anatomy of Quercus (section Erythrobalanus-Fagaceae) species in different light environments

Physiological and anatomical attributes of leaves were examined of three species of Quercus section Erythrobalanus. All three species occur in moist temperate deciduous forests of eastern North America. Seedlings of each species were grown in different light conditions for comparison. The attributes measured were net photosynthesis, stomatal conductivity, blade and cuticle thickness, stomatal density, thickness of upper and lower epidermis, and thickness of palisade mesophyll. The results generally demonstrate the close association between anatomical adaptations and efficiency of physiological processes; they also elucidate the distribution patterns of the three Quercus species across the forest topography in southern New England. The most drought-tolerant and light-demanding species, Q. velutina (Lam.), exhibited the greatest leaf anatomical plasticity, the highest net photosynthesis in the different light conditions, and the lowest stomatal area per unit area of leaf. The most drought-intolerant species, Q. rubra (L.), exhibited the least leaf anatomical plasticity, the lowest net photosynthesis in the different light conditions, and the highest stomatal area per unit area of leaf. Quercus coccinea (Muenchh.) usually exhibited values that were intermediate between Q. rubra and Q. velutina.     

Nonspecific light loss and intrinsic DNA variation problems associated with feulgen DNA cytophotometry.

Nonspecific light loss by the cell-wall-plus-cytoplasm (CWC) can cause a 50% increase in Feulgen absorption units in peanut root-tip nuclei as determined by scanning at 450 nm, whereas this phenomenon is not evident with chicken erythrocytes. A two wavelength scanning method of subtracting nonspecific 450 nm absorption from 550 nm Feulgen absorption values eliminated the nonspecific light loss in CWC, However, the two wavelength scanning method is time consuming and somewhat impractical with a regular scanning microdensitometer such as Vickers M85. Elimination of the problem of nonspecific light loss is suggested by careful determination of background setting with the spot position close to the nucleus in CWC. The accuracy of the CWC background setting method was further tested by comparison with subtraction method. The use of plant nucleis as an internal standard in plant DNA measurements was also evaluated. Significant variation among the replicate slides due to the variation in pine nuclear DNA amounts was observed and plant nuclei generally are not reliable internal standards. Mature chicken erythrocytes are recommended as an internal standard because the cell type and metabolic state is known.     

First record of lily thrips, Liothrips vaneeckei Priesner, in Australia (Thysanoptera: Phlaeothripidae)

The first Australian record of the lily thrips, Liothrips vaneeckei Priesner, is reported from a bulb farm in Warragul South, Victoria. It is an occasional pest of Lilium bulbs, both in the field and in storage, particularly in the USA and several European countries, and is also infrequently found in considerable numbers on the corms of orchids.     

Spectral reflectance and photosynthetic properties of Betula papyrifera (Betulaceae) leaves along an elevational gradient on Mt. Mansfield, Vermont, USA

We studied relationships between spectral reflectance and photosynthesis of mountain paper birch, Betula papyrifera var. cordifolia (Regel) Fern., leaves from three different elevations on Mt. Mansfield (summit elevation 1339 m above sea level) in the Green Mountains of Vermont, USA. The different reflectance indices we used all suggested progressively increasing stress with increasing elevation. The photochemical reflectance index (PRI) indicated lower photosynthetic radiation use efficiency at higher elevations, the red edge position (λRE) indicated lower chlorophyll concentrations at higher elevations, and the structure-independent pigment index (SIPI) indicated a higher carotenoid?:?chlorophyll a ratio at higher elevations. The rate of change in these indices with changes in elevation was much higher than we have observed in our studies of red spruce and balsam fir reflectance along a similar elevational gradient; we take this to be an indicator of the greater susceptibility of paper birch to elevation-related stressors compared to the very stress-tolerant conifers. At all light levels, photosynthesis decreased with increasing elevation; this pattern was most noticeable in the light-saturated rate of photosynthesis (A(sat)), which was nearly twice as high in low-elevation leaves (17.0 ± 1.0 μmol·m(-2)·s(-1)) than in high-elevation leaves. The quantum yield of photosynthesis (Φ) exhibited a similar trend. Furthermore, the highest elevation leaves showed a much sharper transition from the light-limited to the light-saturated part of the light response curve than did the lowest elevation leaves. The photochemical reflectance index was highly correlated with A(sat) (r(2) = 0.99) and Φ (r(2) = 0.96). In addition to contributing to our knowledge of the ecophysiology of paper birch along a steep environmental gradient, these results are further evidence of the usefulness of reflectance measures for the rapid and noninvasive detection of plant stress, especially when used in conjunction with direct measurements of photosynthesis.     

Spectral reflectance of Picea rubens (Pinaceae) and Abies balsamea (Pinaceae) needles along an elevational gradient, Mt. Moosilauke, New Hampshire, USA

Relationships among elevation, foliar morphology, spectral reflectance, and chlorophyll fluorescence of two co-occurring montane conifers, red spruce (Picea rubens Sarg.) and balsam fir (Abies balsamea [L.] Mill.), were investigated along two transects from 460 to 1460 m on Mt. Moosilauke in the White Mountains of New Hampshire, USA. Spectral reflectance (300-1100 nm wavelengths) and the chlorophyll fluorescence F(v)/F(m) ratio were measured on dark-adapted needles. Foliar morphology (needle size, shape, and mass) and nitrogen concentrations were measured in the laboratory. Reflectance spectra varied between species and with elevation. Two chlorophyll measures, red edge position and a chlorophyll-based difference index (Chl NDI = R750 - R705/R750 + R705), indicated more chlorophyll in fir than in spruce and decreasing chlorophyll with increasing elevation in both species. The structure-independent pigment index (SIPI = R800 - R445/R800 - R680) increased with elevation, indicating an increasing carotenoid?:?chlorophyll ratio. The photochemical reflectance index (PRI = R531 - R570/R531 + R570), a measure of photosynthetic radiation use efficiency, decreased with increasing elevation up to 1370 m. In the highest elevation site, within the stunted alpine krummholz at 1460 m, PRI was higher than at 1370 m, but still lower than at 1070 m. This same pattern was evident in the chlorophyll fluorescence F(v)/F(m) measurements. These independent indices indicate higher stress in spruce than fir, which may be related to the "spruce decline" reported in the northeastern USA. Results also indicate progressively increasing stress with increasing elevation up to 1370 m. Stress appears to be lower at 1460 m than at 1370 m, despite the harsher conditions at the very summit of Mt. Moosilauke. This may be a consequence of stress-tolerant physiology and/or prostrate architecture.