Epidermoid splenic cyst presented as huge splenic abscess: a case report.

Epidermoid splenic cysts are very rare. Symptoms emerge because of enlargement, infection, haemorrhage or rupture. Although splenectomy is indicated for large cysts, minimally invasive and preservation procedures, such as partial splenectomy or total cystectomy with splenorrhaphy, have been increasingly used during the last decade. We report herein the case of a 16-year old female presented with left upper abdominal quadrant pain, fever and abdominal distention treated in our department.

Stronglyoides ransomi: factors influencing the in vitro development of the free-living generation.

Among the progeny of parasitic females of Strongyloides ransomi, ransomi, males did not appear in significant numbers until the 7th week of infection in cases of simple infection, and until the 3rd week of infection in cases of multiple infection. The appearance of males was attributed to the effect of host immunity, the physiological ageing of the parasitic females, or both. Type of culture substrate and other cultural conditions did not influence the percent of larvae developing into males. Sex of larvae was determined prior to hatching, probably during oogenesis or embryogenesis. Culture conditions influenced the direction of development of female larvae. An initial pH below 5.9 or above 7.2 favored differentiation of larvae into infective larvae, whereas, intermediate initial pH levels favored development of free-living females. Baby pig substrate, autoclaved substrate, and substrate washed free of soluble chemicals (adverse cultural conditions) promoted differentiation toward infective larvae. Adult pig substrate, nonautoclaved substrate and unwashed substrate promoted differentiation toward free-living females. In general, adverse conditions inside the host and favor an indirect life cycle.

Cytology, reproduction, and sex determination of Strongyloides ransomi and S. papillosus.

Parasitic females of Strongyloides ransomi and Strongyloides papillosus have 4 chromosomes and reproduce exclusively by mitotic (apomictic) parthenogenesis. The free-living generation includes females and males. The females have 2 pairs of chromosomes of unequal size and reproduce by meiotic parthenogenesis following obligatory pseudofertilization (gynogenesis). The males undergo spermatogenesis by the regular meiotic process and have the same chromosomal complement as the females. During prophase I, however, a portion of one homologue of the large bivalent breaks free and subsequently is diminished, as in S. ransomi, or it rejoins the original homologue, as in S. papillosus. This behavior of meiotic chromosomes during spermatogenesis suggests that the karyotype of these species has evolved from a karyotype analogous to that of Strongyloides ratti with 2 pairs of autosomes and a pair of X chromosomes, following fusion of the X chromosome with an autosome and the formation of a Neo-X and a Neo-Y chromosome. The female karyotype of S. ransomi and S. papillosus thus may be 2A + 2 Neo-X. The males are phenotypic males and have the same karyotype as the females, but their functional karyotype may be 2A + Neo-X + Neo-Y.

The effect of methylprednisolone on the sodium and water content of the dog lung after hemorrhagic shock.

Out of 17 mongrel dogs, 3 were subjected on one and two hours of hemorrhagic shock, while the remaining four served as controls. In five of the thirteen dogs, 30 mg/kg of methylprednisolone sodium succinate were administered intravenously one hour after hemorrhage. All animals were sacrificed at the end of the experiment, their lungs were removed and the sodium and water content was measured. The sodium content was found to be markedly increased at the end of two hours of hemorrhagic shock. This increase was prevented significantly by the administration of pharmacological doses of methylprednisolone given at one hour of hemorrhagic shock. No significant change in total lung water was noted, even after two hours of hemorrhagic shock. The results of this study suggest that early intravenous administration of large doses of methylprednisolone may be beneficial to patients in protracted hemorrhagic shock, who are at high risk of developing pulmonary complications.

Hermaphroditism in Meloidogyne hapla.

Hermaphrodites were detected in diploid and polyploid isolates of population 86-Va of Meloidogyne hapla. Young hermaphrodites are indistinguishable from normal females. Initially, hermaphrodite ovaries are filled with oocytes at various stages of development. Hermaphroditism is expressed later when young oocytes in the early pachytene region of the growth zone suddenly advance to diakinesis and proceed with maturation divisions, resulting in spermatid production. Spermatogenesis may be initiated shortly after the fourth molt, or later, after a female has produced some eggs. Spermatogenesis may occur in one or both gonads, and it may be initiated in one gonad before the other. Once initiated, spermatogenesis continues for the entire reproductive life of the hermaphrodite. Several thousand spermatozoa accumulate in the ovotestis. Because they do not pass through the oviduct into the spermatotheca, they do not take part in reproduction (nonfunctional hermaphroditism). Among the progeny of hermaphrodites, ca. 50% are hermaphroditic, and the remainder are apparently normal females which, however, produce about 50% hermaphroditic progeny. Two temperature regimes (20-23 C and 27-30 C) did not influence the percentage of hermaphrodites among the progeny. Hermaphroditism could not be transmitted to nonhermaphroditic isolates following attempted crosses between males of hermaphroditic and females of nonhermaphroditic isolates. Although this result suggests cytoplasmic rather than nuclear inheritance, this conclusion is not definitive.

Further studies on the role of polyploidy in the evolution of meloidogyne.

Two tetraploid isolates of Meloidogyne hapla, 86P and E289P, with haploid chromosome numbers of 34 and 28, respectively, were studied cytogenetically and biologically in relation to the diploid populations, 86-Va (n = 17) and E289-Taiwan (n = 14), from which they had been originally isolated. Both isolates were quite stable, converting to diploidy at the low rate of about 2.5%. The tetraploid isolate 86P maintained itself in competition with its diploid counterpart in mixed cultures, although an initial frequency of 50% polyploidy was reduced to about 9% at the end of the sixth generation. Both tetraploid isolates could maintain themselves in greenhouse cultures without artificial selection for at least 2 years. Crosses between diploid females and tetraploid males resulted in a few triploid females that produced mostly nonviable eggs, suggesting partial reproductive isolation between the two ploidy forms. Ten generations of propagation of only polyploid females of isolate 86P that were associated with males failed to yield an obligatorily amphimictic isolate that would not convert at all to diploidy. If one accepts a previous assumption that the present day amphimictic root-knot nematodes are tetraploids derived from diploid ancestors, results of the present study are not inconsistent with an evolutionary trend toward an even higher level of ploidy in Meloidogyne, presumably octaploidy.

Oogenesis and the chromosomes of twelve bisexual species of heterodera (nematoda: heteroderidae).

Twelve bisexual species of Heterodera reproduced by amphimixis and had the same number of n=9 (2n=18) chromosomes in maturing oocytes. H. schachtii had slightly larger chromosomes than all other species. Only sperm nuclei with n=9 chromosomes were observed inside maturing oocytes and no specialized sex chromosomes were detected in any case. A "supernumerary" chromosome was observed occasionally in oocytes of H. schachtii and H. weissi and was transmitted regularly to one-half of the progeny of the nematodes that possessed it. Cytological characteristics were not very instructive in differentiating amphimictic tleterodera species. Such karyotypic uniformity indicates cytogenetic stability of the genus and close interrelationship among its members.

Genetic structure of races of Heterodera glycines and inheritance of ability to reproduce on resistant soybeans.

Four field populations of Heterodera glycines tested for ability to reproduce on three host differentials were each classified into one of the recognized races. A fifth population represented a new race. Genetic analysis indicated that the designated races are actually field populations that differ from each other primarily in the frequencies of three groups of genes (genes for parasitism) that act quantitatively and control the ability of the nematode to reproduce on resistant P.I. 88788, Pickett, and P.I. 90763 soybeans. Populations of race-3 have none of these genes for parasitism, or they have some in low frequency that results in an index of parasitism of less than 10 on any one of the resistant soybeans. Race-1 has a high frequency of one group of genes that enable it to reproduce on P.I. 88788. Race-2 has two groups of genes for parasitism in high frequency; one for P.I. 88788, and one for Pickett. Based on these findings, it was assumed that race-4 has three groups of genes for parasitism; one for P.I. 88788, one for Pickett, and one for P.I. 90763. Additional races may be recognized when new genes are identified, or when new gene combinations are discovered. The ability to reproduce on P. I. 88788 is inherited independently from the ability to reproduce on Pickett. Although the genetic structure of field populations does not provide a solid foundation for race designation, recognizing races under the present system may be useful when it clearly characterizes the behavior of field populations. Race designations, however, should be regarded as provisional since gene frequencies change with time in response to selection forces and, therefore, the race status of a population may change accordingly.

Oogenesis and the Chromosomes of the Parthenogenic Root-knot Nematode Meloidogyne incognita.

220 populations of Meloidogyne incognita and related forms from 46 countries reproduced by mitotic parthenogenesis (apomixis). Determination of somatic chromosome numbers from oogonia and oocytes revealed the existence of a predominant, possibly triploid race A with 3n = 40 to 46 and a rare, diploid race B with 2n = 32 to 36 chromosomes. There is no correlation between cytological races and the four recognized host races of this species. The characteristic behavior of prophase I chromosomes of maturing oocytes, which results in a prolonged prophase stage, is a unifying feature of all forms of M. incognita and supports monophyletic evolution, distinct from that of other Meloidogyne species. Extensive chromosomal polymorphism detected among populations can be helpful in elucidating the cytological pathway of evolution of the species.

Gametogenesis and the Chromosomes of Meloidogyne nataliei: Not Typical of Other Root-knot Nematodes.

Studies of oogenesis and spermatogenesis revealed that Meloidogyne nataliei is a diploid, amphimictic species with four (n), relatively large chromosomes, and possibly with an XX female symbol-XY male symbol mechanism of sex determination. It differs considerably from all other amphimictic, or meiotically parthenogenetic, species of Meloidogyne which have 13-18 smaller chromosomes and from Meloidogyne (Hypsoperine) spartinae which has seven. Consequently, the taxonomic position of M. nataliei needs to be re-evaluated. The chromosomes of M. nataliei and their behavior during gametogenesis resemble more closely chromosomes of the genus Heterodera than those of the genus Meloidogyne. This resemblance, however, may not imply a closer phyletic relationship of M. nataliei to heteroderid nematodes.

Oogenesis and Reproduction of the Birch Cyst Nematode, Heterodera betulae.

Cytological study revealed that maturation of oocytes of Heterodera betulae is by regular meiosis and reproduction is by parthenogenesis. Restoration of the somatic chromosome number occurs after telophase II and before egg pronucleus formation, in the absence of a mitotic apparatus through a type of endomitotic division. The haploid chromosome number is 12 (2n = 24) in 95% of the female nematodes studied and 13 in the remaining 5%. The phylogenetic relationship of H. betulae with most other Heterodera species having n = 9 is not clear.

Oogenesis and the Chromosomes of the Cystoid Nematode, Meloidodera floridensis.

Three Meloidodera floridensis populations of different geographic or host origin all reproduced by mitotic parthenogenesis. One of them from pine had a somatic chromosome number of 26, whereas, another population from pine and one from azalea had 2n = 27 chromosomes. All are considered to be triploid forms derived from an amphimictic ancestor with n = 9 chromosomes, the basic number in the closely related genus Heterodera. Evidence is presented which suggests that during division the chromosomes of the germ-line cells of the developing embryo behave differently than the chromosomes of all other blastomeres.

Gametogenesis and Reproduction of Meloidogyne graminis and M. ottersoni (Nematoda: Heteroderidae).

Oogenesis and spermatogenesis of seven populations of Meloidogyne graminis and one population of M. ottersoni (formerly Hypsoperine spp.) were of the meiotic type. When males were abundant, reproduction was by amphirnixis. In most greenhouse cultures, however, males were rare and reproduction was by meiotic parthenogenesis. M. graminis and M. ottersoni are closely related to each other and to M. graminicola and M. naasi, but differ in some respect from other Meloidogyne species. It is suggested that these four species be treated together as a group of species, either in the genus Meloidogyne or in the genus Hypsoperine.

Gametogenesis and the Chromosomes of Two Root-knot Nematodes, Meloidogyne graminicola and M. naasi.

Oogenesis and spermatogenesis were studied in populations of M. graminicola and M. naasi from which the species were originally described. Maturation of oocytes and spermatocytes in both species was by normal meiosis. The haploid chromosome number determined during the first and second maturation divisions was n = 18 with no variation. The somatic chromosome number determined in early cleavage divisions and, to a limited extent, in oogonial divisions was 2n = 36. Reproduction was regularly by meiotic parthenogenesis in both species. Re-establishment of the somatic chromosome number in mature oocytes, apparently took place through fusion of the second polar nucleus with the egg pronucleus. Occasional reproduction by cross-fertilization was demonstrated in M. graminicola and it is suspected in M. naasi in cultures with abundant males. Phylogenetic relationships in the family Heteroderidae are discussed in the light of the new cytological information. The peculiar behavior of nucleoli persisting during metaphase, anaphase and telophase of cleavage divisions is reported.

Cytogenetic Status of Meloidogyne (Hypsoperine) spartinae in Relation to Other Meloidogyne Species.

Four populations of Meloidogyne spartinae from the coast of North and South Carolina were identical cytogenetically. Fourteen rod-shaped chromosomes were present in oogonia and spermatogonia, whereas seven bivalents were observed in oocytes and spermatocytes. There were no distinguishable sex chromosomes. Chromosome behavior was similar to that of other Meloidogyne species. A slight deviation in morphology of prometaphase bivalents was attributed to an increase in frequency of chiasmata that may be associated with the obligatorily amphimictic reproduction of this nematode. The anatomy of the oviduct-spermatotheca region and most cytogenetic features studied suggested that M. spartinae can be regarded as a root-knot nematode. Its position in the genus Meloidogyne or Hypsoperine can be decided by taxonomists. Its small chromosome number (n = 7) compared to the larger number (n = 13-19) of other Meloidogyne species suggests that, cytologically, M. spartinae stands closer to the ancestral form from which the prescent day root-knot nematodes have evolved.

Gametogenesis in amphimictic and parthenogenetic populations of Aphelenchus avenae.

The female reproductive system of Aphelenchus avenae, studied in orcein-stained material, showed a peculiar structural pattern not yet reported in other nematodes. Chromosome morphology and behavior during gametogenesis could be studied in more detail than in other tylenchid or aphelenchid species investigated to date. In a bisexual population from Australia, gametogenesis was by normal meiosis and reproduction by amphimixis. The haploid chromosome number was n=8 in both males and females, and no sex chromosomes were detected. Three monosexual populations from Australia, California, and North Carolina underwent oogenesis by meiosis but reproduced hy parthenogenesis. The haploid chromosome number was n=8 in the Australia and the North Carolina populations, but n=9 in the California population. Spermatogenesis in temperature-induced males of the California population was by normal meiosis, and sperm had n=9 chromosomes. Most chromosomes consisted of a central euchromatic section and two characteristic heterochromatic ends. No centromere was observed in any chromosome. The relationship between the California population with n=9 and all the other populations with n=8 chromosomes is not well understood.

Observations on development of the gonad and on reproduction in Aphelenchus avenae.

Nuclear changes occurring in male and female gonads of Aphelenchus avenae during postembryogenesis were studied in relation to time and feeding periods on Rhizoetonia solani. Development of the female gonad was similar to that in other nematode species, but development of the male gonad followed the growth pattern of female rather than male gonads. This deviation was explained by the assumption that males in antphimictic populations have appeared as the resnlt of recent evolntion of such populations to sexuality from originally parthenogenctic ancestors. A certain, period of feeding of larvae (16 h for L-2 and L-3, but 12 h for L-4) was required before molting. Cell divisions were confined to the periods of lethargus during the second and third molts, but started during the larval stage in fourth-stage larvae. Crosses in various combinations demonstrated that temperature-induced males do inseminate fentales of the amphimictic and some parthenogenetic populations, but their spermatozoa are nonfunctional. Similarly, males of the amphimictic population inseminated females of a parthenogenetic population, but the sperm did not penetrate the oocytes.

Polyploidy in an Amphimictic Population of Heterodera glycines.

A tetraploid single-cyst isolate of Heterodera glycines from a field population from Indiana has been propagated in the greenhouse on Lee soybeans since its discovery, in 1973. The tetraploid isolate has n = 18 chromosomes, compared with n = 9 of the diploid H. glycines; it has larger cysts and larvae, but shows the same level of parasitism and host range as the diploid population from which it apparently evolved. Association of chromosomes is irregular at metaphase I, with quadrivalents, trivalents, and univalents often observed in addition to the bivalents. The second maturation division is usually normal. About 80% of the mature oocytes (just before fertilization) have n = 18, and the other 20% have n = 17 or 19. Reproduction of the tetraploid isolate is exclusively by cross-fertilization. The discovery of such a tetraploid provides an experimental tool for the study of polyploidy in nematodes. Many amphimictic plant-parasitic nematodes are suspected of representing polyploids.

Use of enzyme phenotypes for identification of meloidogyne species.

Enzyme phenotypes were obtained for 291 populations from 16 species of Meloidogyne originating from 65 countries. Soluble proteins from macerates of individual egg-laying females were separated by electrophoresis in 0.7-mm-thick polyacrylamide gels. Enzymes investigated were nonspecific esterases, malate dehydrogenase, superoxide dismutase, and glutamate-oxaloacetate transaminase. Esterases were polymorphic and most useful in identification of major species. About 94% of the populations of M. hapla, 98% of M. incognita, and 100% of M. javanica could be identified to species on the basis of esterase phenotypes alone. About 84% of the populations of M. arenaria exhibited three distinct phenotypes. Two of them were highly species specific (accuracy of identification 98-100%). The third, and least prevalent, phenotype occurred also in two other species. Another 12 less common Meloidogyne species, of which only one or a few populations of each were studied, exhibited a variety of esterase phenotypes, some of which may prove to be species specific. Superoxide dismutase phenotypes similarly were helpful in the characterization of certain species; however, the same phenotype was often observed in more than one species. The remaining two enzymes, with few exceptions, proved to be less useful for identification of Meloidogyne species. Multienzyme phenotypes represented by two or more enzymes often offered biochemical profiles more valuable for definitive characterization of Meloidogyne species than single enzymes.

Relative DNA Content and Chromosomal Relationships of some Meloidogyne, Heterodera, and Meloidodera spp. (Nematoda: Heteroderidae).

The relative DNA content of hypodermal nuclei of preparasitic, 2nd-stage larvae was determined cytophotometrically in 19 populations belonging to 13 species of Meloidogyne, Heterodera and Meloidodera. In Meloidogyne hapla, M. arenaria, M. incognita and M. javanica, total DNA content per nucleus is proportional to their chromosome number, indicating that chromosomal forms with high chromosome numbers are truly polyploid. M. graminicola, M. grarninis and M. ottersoni have a DNA content per chromosome significantly lower than that of the other Meloidogyne species. Within Heterodera, species with high chromosome numbers have proportionally higher DNA content, indicating again polyploidy. DNA content per chromosome in Meloidogyne is one third that of Heterodera and one haft that of Meloidodera floridensis. The karyotypic relationships of the three genera are still not clearly understood.