Felid sex identification based on noninvasive genetic samples

We developed two tests for sex identification of felids using y‐chromosome deletions in the zinc‐finger and amelogenin regions. These tests provide positive results for both males and females, while reducing the need to co‐amplify microsatellites to test for DNA quality in hair and scat samples. Furthermore, the y‐chromosome deletions are absent in a wide‐range of prey species; thus, when these tests are used on scat samples, potential contamination caused by prey DNA incidentally extracted, is minimized.     

Observations on lesser-known flatworms: temnocephala

Temnocephala novae-zealandie, a flatworm epizoic on crayfish, was examined by light and electron microscopy to investigate the variation within rhabdocoel turbellarians and to provide information on the possible structural modifications in the evolution of parasitism. The sucker is clearly glandular; the tentacular glands are eosinophilic and at the surface store and often release mucus as a coiled thread; the epidermis is clearly not reduced in structure and contains septate junctions in the anterior portion. Light microscope studies documented the presence of ten pair of paranephrocytes (athrocytes). In the laboratory, egg deposition, survival on and apart from the host and another crayfish, and behavior during the host molt were observed.     

The endocrine cells in the gastroenteropancreatic system of the bowfin, Amia calva L.: an immunohistochemical, ultrastructural, and immunocytochemical analysis.

The gastroenteropancreatic (GEP) endocrine system of bowfin (Amia calva) was described using light and electron microscopy and immunological methods. The islet organ (endocrine pancreas) consists of diffusely scattered, mostly small islets and isolated patches of cells among and within the exocrine acini. The islets are composed of abundant, centrally located B cells immunoreactive to bovine and lamprey insulin antisera and D cells showing a widespread distribution and specificity to somatostatin antibodies. A and F cells are present at the very periphery of the islets and are immunoreactive with antisera against glucagon (and glucagon-like peptide) and several peptides of the pancreatic polypeptide (PP)-family, respectively. The peptides of the two families usually collocates within the same peripheral islet cells and are the most common immunoreactive peptides present in the extra-islet tissue. Immunocytochemistry and fine structural observations characterised the granule morphology for B and D cells and identified two cell types with granules immunoreactive to glucagon antisera. These two putative A cells had similar granules, which were distinct from either B or D cells, but one of the cells had rod-shaped cytoplasmic inclusions within cisternae of what appeared to be rough endoplasmic reticulum. The inclusions were not immunoreactive to either insulin or glucagon antisera. Only small numbers of cells in the stomach and intestine immunoreacted to antisera against somatostatin, glucagon, and PP-family peptides. The paucity of these cells was reflected in the low concentrations of these peptides in intestinal extracts. The GEP system of bowfin is not unlike that of other actinopterygian fishes, but there are some marked differences that may reflect the antiquity of this system and/or may be a consequence of the ontogeny of this system in this species.     

Lectin-gene expression in pea (Pisum sativum L.) roots

The expression of a lectin gene in pea (Pisum sativum L.) roots has been investigated using the copy DNA of a pea seed lectin as a probe. An mRNA which has the same size as the seed mRNA but which is about 4000 times less abundant has been detected in 21-d-old roots. The probe detected lectin expression as early as 4 d after sowing, with the highest level being reached at 10 d, i.e. just before nodulation. In later stages (16-d- and 21-d-old roots), expression was substantially decreased. The correlation between infection by Rhizobium leguminosarum and lectin expression in pea roots has been investigated by comparing root lectin mRNA levels in inoculated plants and in plants grown under conditions preventing nodulation. Neither growth in a nitrate concentration which inhibited nodulation nor growth in the absence of Rhizobium appreciably affected lectin expression in roots.Abbreviation cDNA copy DNA - poly(A)⁺RNA polyadenylated RNA     

Ultrastructure of organelles during microsporogenesis inTillandsia pallidoflavens (Bromeliaceae)

InTillandsia pallidoflavens none of the organelles undergoes fundamental de- and redifferentiation during microsporogenesis. The plastids are amoeboid, exhibit complex internal structures and gradually start accumulating polysaccharides from meiotic prophase I onwards. These observations contradict reports for other taxa. The ultrastructure of mitochondria and dictyosomes, respectively, is more or less orthodox. The extensive ER, which is only poorly stained by standard methods was identified by image intensifiying techniques. The ribosomes are not only associated with the ER or occur as polyribosomes free in the cytoplasm, but can also form more or less dense clusters.     

Root turnover and production by14C dilution: implications of carbon partitioning in plants

Summary Estimates of belowground net primary production (BNP) obtained by using traditional soil core harvest data are subject to a variety of potentially serious errors. In a controlled growth chamber experiment, we examined the aboveground-belowground, labile to structural tissue, and plant to soil dynamics of carbon to formulate a¹⁴C dilution technique for potential successful application in the field and to quantify sources of error in production estimates.Despite the fact that the majority of net¹⁴C movement between above- and belowground plant parts occurred between the initial labeling and day 5, significant quantities of¹⁴C were incorporated into cell-wall tissue throughout the growing period. The rate of this increase at late sampling dates was greater for roots than for shoots. Total loss of assimilated¹⁴C was 47% in wheat and 28% in blue grama. Exudation and sloughing in wheat and blue grama, respectively, was 15 and 6% of total uptake and 22 and 8% of total plant production.When root production estimates by¹⁴C dilution were corrected for the quantities of labile¹⁴C incorporated into structural carbon between two sampling dates, good agreement with actual production was found. The error associated with these estimates was ±2% compared with a range of –119 to –57% for the uncorrected estimates. Our results suggest that this technique has potential field application if sampling is performed the year after labelling.Sources of errors in harvest versus¹⁴C dilution estimates of BNP are discussed.     

Comparison of rates of natural senescence of the root cortex of wheat (with and without mildew infection), barley,oats and rye

Summary In comparative tests in a glasshouse, the cortex of oat and rye roots senesced more slowly than the cortex of wheat and barley roots. Of the cereals tested, wheat showed the most rapid rate of root cortical senescence, and the rate was unaffected by inoculation of leaves withErysiphe graminis. The results are discussed in relation to infection by root pathogens.     

A novel human type I hair keratin gene: evidence for two keratin hHa3 isoforms

We present the nucleotide and amino acid sequence for a novel human type I hair keratin, which could be identified through its high sequence homology and strict carboxyterminal length identity as a human ortholog of the murine hair keratin mHa3. Our hHa3 sequence differs, however, from that of a previously described hHa3 hair keratin (published only as an amino acid sequence; [13]) in 24 amino acid positions, 8 of which occur in the middle of the carboxyterminal domain. PCR of genomic DNA from 25 normal human subjects using a primer pair derived from sequence segments located in the 3-region of our hHa3 clone that encode conserved amino acid sequences in both keratins, resulted in the amplification of two distinct products of 0.38 kbp and 1.0 kbp. DNA sequence analysis of the cloned PCR products allowed identification of the 0.38 kb sequence as that originating from Yuet al. [13] and the 1.0 kb sequence as that being derived from our data. The difference in fragment length was due to unique intron 6 sequences, indicating that these two keratin species are encoded by genes of their own. Moreover, extensive Southern blot analyses with DNA from 25 unrelated individuals of different races using a 3-noncoding sequence from our keratin and the intron 6 sequence of the keratin of Yuet al. [13], as hybridization probes showed that both keratin genes are present as single copy sequences occurring ubiquitously and without gross alterations in the human genome. Collectively, these data demonstrate that the human type I hair keratin described in this paper represents an isoform of the previously described hHa3 keratin. We propose that these hHa3 isoforms be named in chronological order of discovery hHa3-I and hHa3-II.     

Electromotility of outer hair cells from the cochlea of the echolocating bat,Carollia perspicillata

Isolated outer hair cells (OHCs) and explants ot the organ of Corti were obtained from the cochlea of the echolocating bat, Carollia perspicillata, whose hearing range extends up to about 100 kHz. The OHCs were about 10–30 m long and produced resting potentials between-30 to -69 mV. During stimulation with a sinusoidal extracellular voltage field (voltage gradient of 2 mV/m) cyclic length changes were observed in isolated OHCs. The displacements were most prominent at the level of the cell nucleus and the cuticular plate. In the organ of Corti explants, the extracellular electric field induced a radial movement of the cuticular plate which was observed using video subtraction and photodiode techniques. Maximum displacements of about 0.3–0.8 m were elicited by stimulus frequencies below 100 Hz. The displacement amplitude decreased towards the noise level of about 10–30 nm for stimulus frequencies between 100–500 Hz, both in apical and basal explants. This compares well with data from the guinea pig, where OHC motility induced by extracellular electrical stimulation exhibits a low pass characteristic with a corner frequency below 1 kHz. The data indicate that fast OHC movements presumably are quite small at ultrasonic frequencies and it remains to be solved how they participate in amplifying and sharpening cochlear responses in vivo.Abbreviations BM basilar membrane - FFT fast Fourier Transfer - IHC inner hair cell - OHC outer hair cell