Primary basidiospore charge and taxonomy of Agaricomycetes

This article deals with the polarity of electrostatic charges that are carried on ballistic basidiospores after their liberation from fruiting bodies. The spores were collected by placing a portable device beneath the basidiome and allowing them to fall in a horizontal homogeneous electrostatic field, created by vertical parallel plane electrodes. Thus, the experimental setup enabled to investigate the primary charges, the charges present on spores immediately after the release from spore bearing cells. Spores of 135 basidiomes of 50 species of hymenomycetous fungi were collected in various natural conditions. The non-turgescent (drying up, collapsing or ceasing to sporulate) basidiomes were excluded from the taxonomical analysis; the 128 turgescent basidiomes (223 spore samples) of 47 species were taxonomically analyzed. These species represented eight orders (Agaricomycetes, Basidiomycota), covering 21 families and 36 genera. The analysis showed that the spore charges were distributed according to the polarity similarly in all samples in a species, and in a genus. In most cases also genera of one family had the same type of polarity distribution of spore charges. Possibly all taxa from species to monophyletic families are characterized by specific type of polarity of the primary electrostatic charge of basidiospores. Depending on the taxonomical group, all spore charges were negative, positive, or both negative and positive charges were present. This information could be useful in investing the ballistosporic discharge mechanism and for constructing higher-level phylogeny.     

AS101 Prevents Diabetic Nephropathy Progression and Mesangial Cell Dysfunction: Regulation of the AKT Downstream Pathway

Diabetic nephropathy (DN) is characterized by proliferation of mesangial cells, mesangial expansion, hypertrophy and extracellular matrix accumulation. Previous data have cross-linked PKB (AKT) to TGFβ induced matrix modulation. The non-toxic compound AS101 has been previously shown to favorably affect renal pathology in various animal models and inhibits AKT activity in leukemic cells. Here, we studied the pharmacological properties of AS101 against the progression of rat DN and high glucose-induced mesangial dysfunction. In-vivo administration of AS101 to Streptozotocin injected rats didn’t decreased blood glucose levels but ameliorated kidney hypotrophy, proteinuria and albuminuria and downregulated cortical kidney phosphorylation of AKT, GSK3β and SMAD3. AS101 treatment of primary rat glomerular mesangial cells treated with high glucose significantly reduced their elevated proliferative ability, as assessed by XTT assay and cell cycle analysis. This reduction was associated with decreased levels of p-AKT, increased levels of PTEN and decreased p-GSK3β and p-FoxO3a expression. Pharmacological inhibition of PI3K, mTORC1 and SMAD3 decreased HG-induced collagen accumulation, while inhibition of GSK3β did not affect its elevated levels. AS101 also prevented HG-induced cell growth correlated to mTOR and (rp)S6 de-phosphorylation. Thus, pharmacological inhibition of the AKT downstream pathway by AS101 has clinical potential in alleviating the progression of diabetic nephropathy.     

The gene for the ataxia-telangiectasia variant,Nijmegen breakage syndrome,maps to a 1-cM interval on chromosome 8q21.

Nijmegen breakage syndrome (NBS; Seemanová II syndrome) and Berlin breakage syndrome (BBS), also known as ataxia-telangiectasia variants, are two clinically indistinguishable autosomal recessive familial cancer syndromes that share with ataxia-telangiectasia similar cellular, immunological, and chromosomal but not clinical findings. Classification in NBS and BBS was based on complementation of their hypersensitivity to ionizing radiation in cell-fusion experiments. Recent investigations have questioned the former classification into two different disease entities, suggesting that NBS/BBS is caused by mutations in a single radiosensitivity gene. We now have performed a whole-genome screen in 14 NBS/BBS families and have localized the gene for NBS/BBS to a 1-cM interval on chromosome 8q21, between markers D8S271 and D8S270, with a peak LOD score of 6.86 at D8S1811. This marker also shows strong allelic association to both Slavic NBS and German BBS patients, suggesting the existence of one major mutation of Slavic origin. Since the same allele is seen in both former complementation groups, genetic homogeneity of NBS/BBS can be considered as proved.     

Microgametophytes in flowers with and without fruits ofPhlox drummondii (Polemoniaceae)

Relationships between microgametophyte numbers per flower and fruit-set were sought inPhlox drummondii Hook. This was accomplished by counting fluorescentstained pollen tubes in flowers with and without fruits in 21 populations, and in flowers subject to either supplemental or sparse pollination, and then determining whether the flowers initiate fruits. There was a conspicuous variation in mean pollen tubes per flower (3–38) and in percent fruit-set (17%–92%) among populations. Neighboring populations often differed strikingly in these respects. Flowers with fruits had an average of 15.2 pollen tubes per stigma whereas those without had an average of 3 7 tubes. Over all flowers, there was a mean of 3.7 tubes per ovule. There was a strong correlation between mean tube number within populations and their percent fruit-set (r = 0.86). Supplemental pollination significantly enhanced fruit-set, thereby supporting the notion that fruit-set was pollen-limited in most populations. In both natural and artificial pollinations a portion of flowers without fruits still had several pollen tubes. The occurrence of fruitless flowers containing tubes is explained by attrition factors, like late-acting pollen-pistil incompatibility, and resource limitation. Fruit-set could be initiated with one pollen tube, but this rarely occurred in nature. Higher pollen loads were accompanied by higher percents of fruit-set and number of seeds per flower.     

A supernumerary chromosome with an accumulation mechanism in the lecanoid genetic system

Summary The supernumerary chromosomes of a mealy bug,Pseudococcus obscurus Essig are heterochromatic but show a variable heteropycnosis. In the female, they are weakly heteropyonotic in most tissues, but in a few tissues the individual supernumeraries form striking chromocenters. At oogenesis, they remain unassociated and divide equationally during the first division; during the second, they pair and disjoin. Pairing is usually accomplished by twos so that an unpaired supernumerary is found whenever an odd number, or only one, is present; the unpaired entity is twice as likely to go to the second polar body as to the egg.The normal spermatogenesis in the mealy bugs is a highly modified meiosis in which the paternal heterochromatic set is eliminated from the genetic continuum; during this sequence the supernumeraries are fully heterochromatic up until late prophase I. They then undergo a sharp change in pycnosis and become negatively heteropycnotic. In the second meiotic division they usually segregate with the maternal euchromatic set. Their behavior during spermatogenesis thus becomes an accumulation mechanism since an unreduced number, or nearly that, is transmitted by the males.The variable behavior of the supernumeraries affords further insight into the problem of heterochromatization in the mealy bugs.The supernumeraries may have originated from fragments followed by subsequent duplications. The accumulation mechanism may have been an important factor in their establishment.In genetic systems in which the supernumeraries have an accumulation mechanism, an elimination mechanism might evolve to stabilize the number of supernumeraries. Such elimination mechanisms are known for other genetic systems but have not yet been developed in this mealy bug.The material in this paper is part of a dissertation submitted to the graduate school of the University of California in partial satisfaction of the requirements for the degree of Doctor of Philosophy. This work was supported in part by a National Science Foundation Grant (G-9772) to ProfessorSpencer W. Brown.Predoctoral Trainee in Genetics, National Institutes of Health, 1960–1961.     

Some evidence for the maturity of peripheral adrenergic nerves in new-born guinea-pigs.

The fluorescence histochemical technique of Falck and Hillarp revealed a similar distribution and density of peripheral adrenergic nerves in new-born and adult guinea-pigs. The accumulation of tritiated noradrenaline by tracheae from new-born guinea-pigs, assumed to be uptake into adrenergic nerves, was not less than the accumulation by tracheae from adult animals. There was equal potentiation by cocaine (1 x 10(-5)M) of responses to noradrenaline on tracheal chain preparations taken from new-born and adult guinea-pigs. The evidence supports the hypothesis that the guinea-pig has a functional, well differentiated peripheral adrenergic nervous system at birth. This would account for the apparent inability to produce a long-lasting sympathectomy by administration of 6-hydroxydopamine to new-born guinea-pigs.     

Diploid arrhenotoky and automictic thelytoky in soft scale insects (Lecaniidae: Coccoidea: Homoptera)

Parthenogenesis is reported in three soft scales with 2n=16. In the unfertilized eggs of all three, oogenesis is normal and diploidy is restored by the fusion of the division products of the haploid female pronucleus. In Lecanium putmani Phillips 12 of 13 uninseminated females collected in the wild produced only males. The 21 inseminated females produced 15% males. The males were diploid but contained one euchromatic (E) and one heterochromatic (H) chromosome set. Most of the eggs produced by the inseminated females contained sperm but a few did not. It was concluded, therefore, that females develop from fertilized eggs and males from unfertilized eggs and that the species was diploid arrhenotokous. In L. cerasifex Fitch only 18 of 56 females collected in the wild had been inseminated. The frequency of males among their embryos was 22%. The males were again diploid with one E and one H set of chromosomes. Among the 38 uninseminated females, 27 produced only males, and 10 produced only females. All the female producers contained needle-like bacterial symbionts. Most of the male producers, and most of the inseminated females contained no symbionts; the rest contained rod-like symbionts. It was concluded, therefore, that the females of L. cerasifex studied belonged to two races, a diploid arrhenotokous race and an obligate automictic thelytokous race. Eucalymantus tessellatus (Signoret) is obligate automictic thelytokous. All the females examined were uninseminated and produced only females.Supported by Grant GB 23665 from the National Science Foundation, Washington, D.C.     

Accumulation of B-chromosomes by preferential segregation in females of the grasshopper Melanoplus femur-rubrum

In a population of Melanoplus femur-rubrum 13.9% of the males and 9.1% of the females sampled possessed a metacentric B chromosome (B). In crosses of females with one B (1 B females) and 0 B males 0.82 ± 0.05 of the offspring received the B. The value expected from Mendelian segregation is 0.5. In crosses of 1 B males and 0 B females the frequency of offspring receiving the B was 0.53 ± 0.02. The B is heterochromatic during prophase I of spermatogenesis but is euchromatic during prophase I of oogenesis. The observation that in 1 B females only one B was present in metaphase I of oogenesis suggested strongly that the high rate of transmission of the B by the females resulted from preferential segregation of the B into the secondary oocyte. The maintenance of the B in the species in discussed.Supported by Grant GB 23665 from the National Science Foundation, Washington, D.C.     

Endomitosis in the mealy bug,Planococcus citri (Homoptera: Coccoidea)

Endomitosis in the Malpighian tubules of the mealy bug Planococcus citri (Risso) is described. The stages are identified on the basis of the length of the chromosomes and the distance between the sister chromatids or chromosomes. The appearance of the chromosomes in the various stages of endomitosis is compared to that in other hemipteran insects. During anaphase and telophase of endomitosis the ends of the sister chromatids and chromosomes tend to stay together longer than the other parts. It is suggested that in holokinetic chromosomes special regions for holding the chromatids together are concentrated near the ends of the chromosomes.Supported by grant GB1585 from the National Science Foundation, Washington, D.C.     

A modified Comstockiella chromosome system in the olive scale insect,parlatoria oleae (Coccoidea: Diaspididae)

Summary A modified Comstockiella chromosome system is described in the olive scale insect, Parlatoria oleae (Colvée), in which one, two, or three pairs of chromosomes may play the D role during spermatogenesis.In the male, one set of chromosomes became heteropycnotic in the embryo and remained so until spermatogenesis. Prior to the meiotic prophase, some of the heteropycnotic (H) chromosomes became euchromatic and the number of these chromosomes was cyst-specific. Those chromosomes of the H set which remained heteropycnotic are referred to as D^H elements and these chromosomes together with their euchromatic (E) homologues are called the D pairs.During prophase and metaphase, 4 E and from one to three H elements were present. The number of H elements was considered to be an indication of the number of pairs which did not undergo pairing (D pairs). Thus in cysts with 1H and 4 E elements, 3 of the E elements were considered to be bivalents while 1 E and 1H elements were considered to be univalents.All the chromosomes at metaphase were of about the same size. This was taken to mean that the univalents replicated prior to meiosis while the bivalents did not.During anaphase, all the elements divided, with 4 E and from one to three D^H derivatives going to each pole. In the stages which followed telophase, the D^H derivatives segregated from the 4 E chromosomes. During spermiogenesis, only the nuclei with the E chromosomes formed functional sperm.On the basis of the analysis of pairing in the Comstockiella system and in other coccids, it is suggested that in the Comstockiella system, and probably also in other coccids, when pairing is not associated with chiasma formation, the homologues entering pairing are unreplicated chromosomes.The modified Comstockiella system found in P. oleae is called the multiple-D variant and is considered to be an intermediate between the lecanoid and the simple Comstockiella systems. The presence of such intermediates was predicted by Brown (1963 and 1964) who considered the evolution of the Comstockiella system to be the product of automatic frequency response.Postdoctoral Trainee in Biology, U.S. Public Health Service 1962–1963.