Schizogony in Haemoproteus columbae Kruse*

SYNOPSIS To fill in some of the gaps in our knowledge of Schizogony of Haemoproteus columbae Kruse, transmission experiments involving inoculation into pigeons (Columba livia Gmelin) of sporozoites from salivary glands of the hippoboscid fly Pseudolynchia canariensis (Macquart) were carried out. We were unable to detect prepatent schizonts or to observe schizogonic development when infection became chronic. Schizonts were mainly confined to lung tissue. Observations of parapatent schizonts were made in smears and tissue sections. A variety of forms was found. Cytomeres were rarely encountered. Two types of morphologically distinct merozoites were seen. One type was twice as large as the other and was thought to repeat the process of schizogony several times before invading erythrocytes. Schizonts with cytoplasmic clefts were not common in our material due to the fixatives used (Bouin's and Carnoy's). Merozoites were occasionally observed inside monocytes, probably being phagocytosed.     

Fine Structure of Haemoproteus columbae Kruse During Macrogametogenesis and Fertilization*

When blood is withdrawn from a pigeon (Columba livia) infected with gametocytes of Haemoproteus columbae, differentiation of the gametes begins immediately. This study examines the formation of the macrogamete and its fertilization. The first visible signs of differentiation are the elongation of the nucleus along with the appearance of an intranuclear spindle and atypical centrioles. Then maturation bodies, the products of nuclear reduction, form in both erythrocytic macrogametocytes and macrogametocytes free of their host cells. Penetration of the macrogamete by the microgamete occurs rapidly. Their plasma membranes fuse, and the microgamete's nucleus, axonemes and cytoplasm enter the macrogamete. The nucleus of the microgamete expands and migrates to lie at an angle to the macrogamete nucleus. The 2 fuse across a small area. The nuclear envelope and the plasma membrane of the zygote are a mosaic of the membranes of the 2 gametes.     

An Electronmicroscopic Study of the Microgamete of Haemoproteus columbae Kruse*

SYNOPSIS. Microgametes of Haemoproteus columbae were studied by light microscopy and electron microscopy, using the single-stage replication technic. The filiform microgamete has a swelling or vesicle near the round end; the opposite end is asymmetrically tapered. The gamete is polarized, for it travels in sinuous movements with the round end (the putative anterior end) directed forward. There is no flagellum or undulating membrane and no mitochondrion. The vesicle may contain energy reserves for locomotion or lytic enzymes for penetration. Tubular material often is seen coming from the vesicle and anterior end and may be a kind of acrosomal filament.     

Fine Structure of Haemoproteus columbae Kruse During Differentiation of the Ookinete*

Ookinete differentiation begins in vitro～1 hr after blood infected with mature gametocytes of Haemoproteus columbae is withdrawn from a pigeon. In the undifferentiated zygote, dense material accumulates at the point under the plasma membrane. The conoid and conoidal rings condense from this material. The nucleus is drawn out to a point with the intranuclear spindle (INS) at the peak. Atypical centrioles lie under the forming conoid in the cytoplasm next to the INS. Fibrous material under the inner membrane forms the polar ring from which subpellicular microtubules originate. One hr later the centrioles have disappeared and the nucleus has returned to the center of the organism. The conoidal complex forms the tip of a growing cytoplasmic projection, the anterior end of the ookinete. During this time an elaborate pellicle is differentiating antero-posteriorly; crystalloid formation begins with an extensive proliferation of rough endoplasmic reticulum (ER) continuous with the outer membrane of the nuclear envelope. Crystalloid particles are formed between the lamellae of the ER and collected in a sphere that is later partially surrounded by a small amount of ER. Ookinetes, differentiated 2 hr longer than the ookinetes in vitro, were obtained from the gut of the pigeon fly, Pseudolynchia maura. The differentiated pellicle of these ookinetes consists of a plasma membrane, an inner membrane layer composed of 2 appressed membranes, and in the anterior end, an electron-opaque lamina immediately under the inner membrane. Anterior to the polar ring, this lamina forms a canopy which, posteriorly, is drawn out into projecting ribs which diminish and disappear in the first third of the organism. Fifty to 60 subpellicular microtubules insert on the polar ring. Ookinetes differentiated in vitro were no more than 4 hr old. They lacked micronemes and retained a pellicular cytostome and “internal cytostomes.” The differentiation of micronemes probably occurs at a later time because they are visible after 6 hr in ookinetes in the fly gut. So many degenerating organisms appeared in vitro after 5 hr that this material was discarded.     

The Fine Structure of Haemoproteus columbae Sporozoites*

SYNOPSIS. The fine structure of Haemoproteus columbae sporozoites has been studied and compared to sporozoite structure as revealed by the light microscope. The sporozoites are ultrastructurally similar to those of other Haemosporidia in that they possess a 3-layered pellicle, subpellicular microtubules, polar ring, micropore, free ribosome-like particles, micronemes, a structure resembling a Golgi complex, an irregular mitochondrion, and a large nucleus. In the anterior region of the sporozoite there are 21–22 regularly arranged longitudinal subpellicular microtubules located peripherally around the cell. In the apical region the microtubules appear thickened on 1 side. The sporozoite of H. columbae has a microneme system in which 1–3 micronemes are associated with the outer pellicular membrane at the anterior end. Micronemes are found throughout the cytoplasm, but occur in greater concentration in the anterior region of the sporozoite. A clear pellicular cavity, located between the polar ring and the termination of the inner pellicular layer, is present at the anterior end of the sporozoite. Vesicular invaginations of the inner pellicular layer have been observed in the anterior region; their function is unknown. Spherical osmophilic bodies are found throughout the cytoplasm.     

Early Stages in the Differentiation of Gametocytes of Haemoproteus columbae Kruse*

SYNOPSIS The sexes of mature gametocytes of Haemoproteus columbae Kruse circulating in the blood of the domestic pigeon can be identified in the electron microscope by the same criteria that distinguish them in the light microscope. The microgametocyte has a large nucleus and pigment granules restricted to the 2 extremities of its halter-shaped cells. The macrogametocyte has dense granular cytoplasm with scattered pigment granules and a small central nucleus. The sex of young gametocytes cannot yet be recognized. When blood containing mature gametocytes is cooled outside the body of the host visible signs of gametogenesis appear within 30 seconds. The earliest signs are increasing electron lucidity of the cytoplasm and separation of the outer membrane from the body of the parasite. The membrane may form vesicles or whorls or lie free in the erythrocyte's cytoplasm. The middle membrane of the parasite becomes the plasma membrane. Axonemes and microtubules appear in the cytoplasm and nucleoplasm of the microgametocyte. The macrogametocyte lags slightly behind the microgametocyte in development. With the first signs of differentiation, the host cell cytoplasm begins to disappear. The fate of the outer membrane and the erythrocyte's cytoplasm suggests the release of a lytic substance by the parasite.     

The Fine Structure of Microgametogenesis in Haemoproteus columbae Kruse*

SYNOPSIS. The structural changes leading to the formation of motile microgametes from a single immobile intracellular gametocyte have been examiued in the electron microscope. After pigeon blood infected with Haemoproteus columbae was exposed to the air at room temperature for a few minutes axonemes appeared in the parasite's cytoplasm and the cytoplasm itself appeared less dense. The axonemes were connected with bundles of intranuclear microtubules that were perhaps spindle fibers. No conventional kinetosomes or centrioles have been observed. After the microgametocyte left the erythrocyte, it assumed the shape of a polarized slug or a dumb-bell. Half of the organism was surrounded by a single membrane and filled by part of the nucleus. The other half was surrounded by the remains of the multiple membranes of the gametocyte and contained pigment granules, mitochondria, axonemes and nuclear extensions. The axonemes and nuclear extensions were segregated at the periphery of the cell, exterior to the gametocyte's inner membrane, and were assembled in situ into microgametes. The mature microgamete appeared to peel off from the gametocyte, leaving a residual body.     

Studies of growth and development of gametocytes in Haemoproteus columbae Kruse.

As determined by their ability to exflagellate and round up, it took the macrogametocyte and the microgametocyte of Haemoproteus columbae in pigeons 68 and 116 h, respectively, after patency to reach maturity. Pigment granules appeared in the undifferentiated gametocytes 8 h after invasion of blood. Vacuoles were observed in young gametocytes and persisted in the older forms. The growth curve of H. columbae is close to the sigmoidal curve for growth in protozoa. Multiple infection was noticed in pigeons with high levels of parasitemia, but no more than 2 gametocytes reached maturity; such multiple infections were rare in relapses. The sex ratio of the gametocytes was 1:1. Strong lateral displacement of the nuclei of infected erythrocytes was the rule; hypertrophy was negligible.     

Gametocyte Maturation,Exflagellation and Fertilization in Parahaemoproteus (=Haemoproteus) velans (Coatney & Roudabush) (Haemosporidia: Haemoproteidae): an Ultrastructural Study*

SYNOPSIS. The structural changes in macro and microgametocytes of Parahaemoproteus velans following removal of infected blood from the avian host were studied in the light and electron microscope. Gametocytes of both sexes round up and soon escape from their host cells. Shortly thereafter they assume a dumbbell shape. The microgametocyte undergoes exflagellation forming 8 slender microgametes. During fertilization the entire microgamete appears to enter the female. The most striking ultrastructural change in the formation of the macrogamete is the condensation and enclosure by a membrane of abundant amophorus dense material seen in the cytoplasm of the immature gametocyte. Maturation of the microgametocyte begins prior to its escape from the host cell. Axonemes are present in the cytoplasm and nuclear reorganization occurs while the parasite is intracellular. Bundles of microtubules associated with condensed chromatin are found in the peripheral cytoplasm of maturing forms and apparently participate in the formation of small compact microgamete nuclei. Each of these filiform structures consists of a dense, centrally located nucleus and a single axoneme lying in flocculent cytoplasm. The nucleus and axoneme of the microgamete are seen free in the cytoplasm of a fertilized macrogamete.     

A Comparative Study of Gametocyte Ultrastructure in Avian Haemosporidia*

The fine structure of gametocytes of 3 avian haemosporidian parasites Plasmodium gallinaceum, Haemoproteus columbae, and Leucocytozoon simondi has been studied and compared by electron microscopy. The gametocytes of all 3 species are bounded by a 3-layered limiting membrane system, possess a cytostome during some portion of their residence within host cells, and their sex can be distinguished by both nuclear and cytoplasmic characteristics. L. simondi differs most significantly from P. gallinaceum and H. columbae in possessing large intranuclear granules, mitochondria associated with pocket infoldings of the nuclear envelope near the atypical centriole complex and compartmentalization of the cytoplasm by segments of closely aligned unit membranes. Further, the cytostome of L. simondi does not appear to be a persistent structure as in the other 2 species and pigment is not present within food vacuoles. L. simondi also is capable of infecting a wider variety of host cells and within leukocytes produces striations of the host nucleus and an apparent spiral banding of the host cell surface. The comparison of P. gallinaceum, H. columbae, and L. simondi gametocytes by electron microscopy leads to the conclusion that Plasmodium and Haemoproteus are more closely related to each other than either of them is on Leucocytozoon. The terminology used to describe certain organelles within the gametocyte's cytoplasm has been reexamined and the relationship of the nucleolus to parasite maturation also is described.     

Fine Structure of Differentiating Oocysts and Mature Sporozoites of Haemoproteus metchnikovi in its Intermediate Host Chrysops callidus*

The fine structure of the sporogonic stages of Haemoproteus metchnikovi has been investigated by electron microscopy. Young oocysts are found beneath the basement membrane of midgut epithelial cells. These eventually protrude outward into the haemocoel space and are surrounded by a distinct oocyst capsule. Sporozoite formation begins with a subcapsular vacuolation. Evagination of the oocyst cytoplasm occurs in regions of membrane thickenings and 100–200 sporozoites are formed about a single sporoblastoid body. Remnants of the ookinete pellicle can be observed in maturing oocysts and always are found in the residual body. The fine structure of the mature sporozoite is essentially similar to that which has been described for other haemosporidia and a spherical body is described in association with the mitochondrion of the sporozoite. The sporogonic stages of H. metchnikovi have features common to the sporogonic stages of Plasmodium and Leucocytozoon that are not held in common by the latter 2 genera, including pattern of sporozoite formation and number of sporozoites formed, the presence of a cytostome and of “crystalloid” in the sporozoite.     

Problems of Growth and Development in the Studies by M.Kh. Chailakhyan

Main vistas of Academician M.Kh. Chailakhyan's inquiry into the problems of plant growth and development are reviewed with the emphasis on the input of his research in elucidating the mechanisms of flowering, tuberization, sex expression, and the integrity of plant organism. The pioneer studies conducted by Chailakhyan and his colleagues on agricultural applications of phytohormones, their synthetic analogs, and other growth regulators are considered. Highlighted is the role of theoretical papers written by Chailakhyan, his lectures, and his brave fight against pseudoscientific trends in the Russian science is stressed.     

Growth, gonadal development and sex ratios of meiogynogenetic diploid sea bass

Gynogenesis showed little effect on general physiology and gonadal development in sea bass Dicentrarchus labrax . Meiogynogenetic fish showed well-developed gonads indicating low occurrence of developmental imbalances even after gynogenesis induction in this species. In addition, the proportion of sexes of meiogynogenetic sea bass was similar to the diploid controls in two independent trials, which did not deviate significantly from a 1:1 male: female sex ratio. Even considering some environmental influence on sex differentiation, as has been previously demonstrated, the fact that the proportion of sexes was similar between gynogenetic and control diploids essentially eliminates the possibility that in the sea bass the females are the homogametic sex. Although the mechanism of sex determination of this species still remains unknown, even after gynogenesis induction, the genetic mechanism of the ZW/ZZ type could probably operate in the sea bass.     

Growth and gonadal development of gynogenetic diploid Scophthalmus maximus

The survival, growth, gonadal development and sex ratios of gynogenetic diploid turbot Scophthalmus maximus between 9 and 36 months of age were investigated. Gynogenesis was induced by activation of freshly collected eggs with diluted (1 : 10 with Ringer) and UV‐irradiated (30000 erg mm⁻²) sperm, followed by a cold shock at −1 to 0° C for 25 min, starting at 6·5 min after fertilization. The exclusive maternal inheritance of the resulting gynogenetic diploids was confirmed in all individuals used in the experiment by microsatellite markers. Mean total length and mass throughout the experiment was higher in the controls than in the gynogenetics. The gonadal development in gynogenetic males proceeded normally, and in gynogenetic females it was delayed during the first sexual maturation but was normal during the second one. The sex ratio was 1 male (M) : 1 female (F) in the controls, as expected, but 1 M : 3 F in the gynogenetics. In a second, independent experiment, carried out with fish originating from different broodstock, however, the sex ratio was 1 M : 1 F in the controls and 0 M : 1 F ( i.e . 100% females) in the gynogenetics. Together, these results suggested that the main sex‐determining genetic component in turbot fits well to female homogamety, in accordance with data from other flatfishes. These results indicate that it will be possible to obtain near or all‐female turbot stocks through induced gynogenesis or by crosses involving hormonally sex‐reversed fish.     

Endosymbiont costs and benefits in a parasitoid infected with both Wolbachia and Cardinium

Theory suggests that maternally inherited endosymbionts can promote their spread and persistence in host populations by enhancing the production of daughters by infected hosts, either by improving overall host fitness, or through reproductive manipulation. In the doubly infected parasitoid wasp Encarsia inaron, Wolbachia manipulates host reproduction through cytoplasmic incompatibility (CI), but Cardinium does not. We investigated the fitness costs and/or benefits of infection by each bacterium in differentially cured E. inaron as a potential explanation for persistence of Cardinium in this population. We introgressed lines infected with Wolbachia, Cardinium or both with the cured line to create a similar genetic background, and evaluated several parasitoid fitness parameters. We found that symbiont infection resulted in both fitness costs and benefits for E. inaron. The cost was lower initial egg load for all infected wasps. The benefit was increased survivorship, which in turn increased male production for wasps infected with only Cardinium. Female production was unaffected by symbiont infection; we therefore have not yet identified a causal fitness effect that can explain the persistence of Cardinium in the population. Interestingly, the Cardinium survivorship benefit was not evident when Wolbachia was also present in the host, and the reproduction of doubly infected individuals did not differ significantly from uninfected wasps. Therefore, the results of our study show that even when multiple infections seem to have no effect on a host, there may be a complex interaction of costs and benefits among symbionts.     

Growth, reproduction and recruitment patterns of the wide-eyed flounder, Bothus podas Delaroche (Pisces: Bothidae), from the Azores

The wide-eyed flounder, Bothus podas, occurs in many East Atlantic sub-tropical and temperate inshore areas and is the dominant flatfish in shallow-water areas around the Azores. The aim of this study was to examine the growth, reproductive biology and recruitment patterns of the wide-eyed flounder in the Azores. Adult fish samples were obtained by spear fishing and SCUBA hand netting at Faial Island. Juveniles were obtained from a complementary monthly beach-seining programme undertaken at Porto Pim Bay, Faial. Sex and development stage were determined by macroscopic examination of gonads, whereas age estimates were obtained by counting the number of opaque bands in the otoliths. In the Azores, B. podas reaches 6 years old, which is more than reported for the central Mediterranean, the only other population of this species that has been studied. The studied population has a sex ratio biased to males, which contrasts to a previous observational study, which noted a female-biased sex ratio. Spawning time, as determined from the gonadosomatic ratio and the macroscopic examination of gonads, was between July and September. This time period agrees with behavioural observations in the same area. Sexual maturity was estimated at a total length (TL₅₀) of 14.1 cm and at an age (A₅₀) of 1.7 years. Small juveniles occur on sandy inshore nursery areas for most of the year, but mainly between July and August each year. The presence of small fish throughout most of the year could suggest a protracted settlement period or slow growth on occasions on the shallow-water nursery grounds.     

血管内皮细胞生长因子及其相关蛋白的结构与功能

血管内皮细胞生长因子（ＶＥＧＦ）是在胚胎发生和创伤愈合过程中启动血管形成的一个高度特异的有丝分裂原,也是一种有效的血管通透性诱导因子,ＶＥＧＦ是胱氨酸结生长因子超家族的一员,它与其受体的结构细节和工能特征为设计分子拮抗剂提供了重要依据。其结构特征和生物学特性使之在缺血组织重组侧支循环,肿瘤预后,肿瘤转移乃至实施基因治疗等领域成为重要的研究对象。     

The Influence of Incubation Conditions and Sex on Growth and Dispersal in Hatchling Lizards

Dispersal is a critical process that has profound influence on ecological and evolutionary processes. Many proximate factors influence natal dispersal, but it is currently unclear whether the conditions experienced during incubation play an important role. We manipulated incubation temperature and used mark–recapture of released hatchlings to test this hypothesis. We tested this hypothesis on the prairie lizard (Sceloporus consobrinus) using two experimental islands in a local reservoir. Incubation conditions influenced some aspects of hatchling morphology, but had little influence on the probability of dispersal. As generally predicted for a polygynous species, males were more likely to disperse than females; however, the growth rate of dispersing vs. resident individuals varied depending on sex. Dispersive male lizards did not grow faster than resident males, whereas female dispersers grew significantly slower than resident females. Although our study was not specifically designed to test for differential costs of dispersal for males and females, this pattern is consistent with recent research demonstrating sex‐specific fitness costs of dispersal.     

微量量热法研究酸奶菌种的适宜生长温度及最佳生长温度

测定酸奶菌种保加利亚孔杆菌、嗜热链球菌及二者混合菌在乳中生长的热谱图曲线,确定了各菌种及混合菌的适宜生长温度范围,计算出了各菌种在不同温度下的生长速率常数。用计算机拟合k-T方程,求出各菌种的最佳生长温度。