Leghemoglobin-like sequences in the DNA of four actinorhizal plants

Summary A cloned cDNA partial copy of a soybean leghemoglobin mRNA was used to probe genomic DNA of four species of actinorhizal plants. Southern blot hybridization revealed the presence of sequences with homology to the leghemoglobin probe in DNA from Alnus glutinosa, Casuarina glauca, Ceanothus americanus and Elaeagnus pungens. The hybridization patterns of the restriction fragments revealed some fragment size conservation between the DNA of soybean and the DNA of four actinorhizal plants which are taxonomically unrelated to soybean or to each other. The results presented here indicate that globin gene sequences are much more widely distributed in the plant kingdom than has previously been thought. Furthermore, if sequence conservation is actually as high as the restriction fragment patterns suggest, the evolution of the DNA surrounding the globin sequences has been highly constrained.     

Extraction of DNA from milligram amounts of fresh,herbarium and mummified plant tissues

Summary We have developed a DNA extraction procedure for milligram amounts of plant tissue. Yields ranged from 0.3–200 nanograms of DNA per milligram of tissue. The factors affecting yield are discussed. Fresh tissue, as well as herbarium specimens (22–118 years old) and mummified seeds and embryos (500 to greater than 44 600 years old) were used. All tissues attempted (57 types from 29 species) yielded measurable amounts of DNA. In no case tested was inhibition observed for restriction enzymes BamHI or EcoRI.     

Comparative study of the antennal lobes and their afferent pathway in the worker bee and the drone (Apis mellifera)

Summary The topography of the antennal afferent path-ways was studied comparatively in the worker bee and the drone of Apis mellifera L. by cellular marking, following localized application of cobalt chloride to the cut end of one antenna. This study dealt principally with the first relay of the afferent pathway in the glomeruli of the antennal lobe. The counting and measurement of all the glomeruli were performed on 5 worker bees and 5 drones. An important sexual dimorphism, represented by 4 large and easily identifiable glomerular complexes, was demonstrated in the drone. In both worker bee and drone, four main regions of the glomerular neuropil were distinguished according to corresponding afferent bundles. The worker possessed 166 glomeruli and the drone 103. The number, position and dimensions of the glomeruli indicated that the glomerular organization was unvarying in worker bees and in drones. Concerning the internal structure of the glomeruli, two types were distinguished: the great majority (95%) exhibited a cortical layer, whereas in the 7 posterior glomeruli the synaptic fields of association seemed to be scattered throughout the whole volume. The main results of this work (glomerular invariance, sexual dimorphism) support the hypothesis of the functional unit of the glomeruli.Unité de Recherche Associée au CNRS, UA 483     

Three classes of signalling molecules on B-cell membranes

The question of whether surface immunoglobulin and Ia molecules have a signalling function in helper T cell-dependent activation of B cells has been evaluated. Two sources of B cells have been used, one a purified population of hapten-binding B cells, the other a B-cell lymphoma, CH12, with known antigen specificity. Evidence is presented that both immunoglobulin and Ia molecules are receptors actively involved in the initial activation of resting B cells. Nevertheless, the requirements for ligand binding to either receptor can be bypassed under appropriate conditions, and the implications of this result for the function of these molecules is discussed. With respect to B-cell Ia, the authors present data that demonstrate two distinct functions of this molecule, one as a restricting element for T-cell activation, the second as a signalling receptor for B-cell excitation. On the CH12 surface, the I-A molecule fulfills the former function, but T-cell interactions with I-A fail to result in B-cell stimulation, suggesting that B-cell Ia may limit helper T cell-B cell interactions. We suggest that the binding of antigen surface immunoglobulin and binding of helper T-cell receptors to the appropriate Ia molecule(s) results in the activation of genes that encode for a third class of membrane B-cell receptors, those that bind B-cell stimulating factors.     

The effects of gonadotropins on metabolism of isolated rat granulosa cells

FSH $\text{in vitro}$, but not LH, increased the O₂ uptake of isolated granulosa cells from 23 day old rats previously treated with DES or with DES and FSH. Dose response studies showed that the cells were most sensitive to FSH when the cellular binding of FSH was highest. LH increased the O₂ uptake of granulosa cells of untreated 30 day old rats. DES treatment inhibited the LH induced rise in O₂ uptake when the rats were implanted with DES capsules unless FSH was injected to induce LH receptors. Addition of dbcAMP $\text{in vitro}$ increased O₂ uptake of granulosa cells from 30 day old rats at concentrations 10X lower than those required to stimulate O₂ uptake in cells from 23 day old rats treated with DES alone.FSH $\text{in vitro}$ increased lactate formation in the absence of added substrates but did not do so when glucose was added to the media. In contrast, LH greatly increased lactate formation with added glucose. Dose response studies showed that less than 0.6 ug/ml LH S21 was effective in increasing lactate above control levels. These data suggest that FSH affects aerobic pathways while LH affects anaerobic pathways in the process of the differentiation of granulosa cells toward luteal cells.It is well known that FSH and LH interact with their target cells in the ovary by binding to specific receptors and that FSH stimulates LH-receptor production (1). Receptor binding by either hormone activates adenylate cyclase (2) raising cyclic adenosine monosphosphate (cAMP) levels (3) and increasing protein kinase activity (4). Such changes probably trigger changes in the major metabolic pathways that support follicular development because cells of corpora lutea have glycogen (5) which is not present in follicular granulosa cells (6–9). Several studies suggest that FSH and LH may regulate metabolic processes in the ovary. LH increases lactate in whole prepuberal ovaries (10,11,12) and also increases the uptake of glucose (13). FSH increases oxygen uptake in chick ovaries (14), rat ovaries (15) and prairie dog ovaries (16). However, only one study has been done using isolated ovarian cells. Hamberger (17) has reported that FSH increased the oxygen uptake of thecal cells of immature rats while LH increased the oxygen uptake of granulosa cells. Since granulosa cells from immature rats are reported to have FSH receptors while theca cells have LH receptors the effects of these hormones appear unclear.The present studies were undertaken to more accurately characterize the actions of FSH, LH, and dibutyryl cAMP (dbcAMP) on the oxygen uptake of isolated granulosa cells and remaining tissues of immature ovaries and to determine the effects of FSH and LH on the production of lactate by granulosa cells.     

The effects of prey size, predator size, and sediment composition on the rate of predation of the blue crab, Callinectes Sapidus Rathbun, on the hard clam, MercenariaMercenaria (Linné)

Sediment preferences of blue crabs, Callinectes sapidus Rathbun, and predation rates on various size classes of the hard clam, Mercenaria mercenaria (Linné), in a variety of sediment types were studied in the laboratory. Blue crabs of all size classes exhibited a preference for sand, mud, and sand/mud rather than crushed oyster shell or granite gravel. Clams were more vulnerable to predation by crabs in sand and sand/mud than in crushed oyster shell or granite gravel. When crabs were given a choice of clam sizes based on carapace width (CW), small crabs (<75 mm CW) consumed 5- and 10-mm shell length (SL) clams. Medium crabs (75–125 mm CW) preferentially consumed 10-mm SL clams. Large crabs (> 125 mm CW) consumed 10- and 25-mm SL clams equally. Blue crabs did not eat clams that were >40-mm SL.     

Virion orientation in cubic crystals of the human common cold virus HRV14

A new cubic crystal form (a = 445.1 A) of space group P23 is reported for human rhinovirus R14. There are four particles per unit cell, each situated on a crystallographic 3-fold axis. The orientation of these particles has been determined with a rotation function and their approximate positions have been derived from a Patterson map. The crystals diffract to at least 2.8 A resolution. Limitations to the possible surface features of the virus are set by a comparison of the cubic and orthorhombic crystal forms.     

Variation in the ribosomal RNA genes among individuals of Vicia faba

Summary Length heterogeneity in the ribosomal repeat of Vicia faba is due to the presence of variable numbers of a 325 bp subrepetitive element within the nontranscribed spacer region. The distribution of size classes among 88 individuals within a population was investigated by blot-hybridization. We find that individual plants can exhibit more than 20 size classes and that hybridization patterns are highly diverse from individual to individual, more so than for any species so far investigated. In contrast, no such differences are observed in patterns for different tissues from a single plant or from parental to F₁ generation. Some changes were observed in the F₂ generation. We conclude that unequal recombination can give rise to the diversity that we observe for the V. faba rDNA repeats.     

Isopenicillin N epimerase activity in a high cephalosporin-producing strain of Cephalosporium acremonium

Summary Isopenicillin N epimerase activity in Cephalosporium acremonium CW-19 is so labile that it has never been detected in sonic extracts. Prior to this work, it had only been obtained by the laborious protoplast lysate procedure. The present work shows that the enzyme is present in sonic extracts of a high cephalosporin-producing strain (C-10) of C. acremonium throughout the fermentation.