The Annual Spermatogenetic Cycle of Tarentola mauritanica L. (Reptilia, Gekkonidae)

1983 ◽  
Vol 4 (2) ◽  
pp. 171-184 ◽  
Author(s):  
E. D'Alterio ◽  
O. Picariello ◽  
G. Ciarcia ◽  
F. Angelini
Keyword(s):  
Southern Italy ◽  
General Pattern ◽  
Early Summer ◽  
Seminiferous Tubules ◽  
Complete Disappearance ◽  
Drastic Reduction ◽  
Cell Stage ◽  
Slowing Down ◽  
June July

AbstractThe gecko Tarentola mauritanica L. of southern Italy shows seemingly a tendentially continuous spermatogenetic cycle throughout the year. However, the amount of sperms produced at the level of the seminiferous tubules varies remarkably in the different months of the year: it is maximum in spring and in early summer, whereas it markedly decreases in June-July, when a drastic reduction in spermatogonial mitoses is observed. The slowing down in the spermatogonial activity not involves the complete disappearance of any definite cell stage of gametogenesis, but spermatogenesis is strongly reduced. In winter there is another slowing down in spermatogenesis, anyhow some new spermatozoa continue to form and to be released, though in extremely limited amounts. The general pattern of spermatogenesis is, therefore, of mixed or thermo-rigostatic type. The epididymis appears well developed throughout the year, showing only in wintera decreased amount of secretion. The epididymal tail acts as a system of spermatozoa storage, so that it is always full of sperms also in the period when the gametogenetic activity is at its minimum.

scholarly journals Seasonal Rainfall Forecasts for the Yangtze River Basin in the Extreme Summer of 2020

2021 ◽  
Author(s):  
Philip E. Bett ◽  
Gill M. Martin ◽  
Nick Dunstone ◽  
Adam A. Scaife ◽  
Hazel E. Thornton ◽  
...  
Keyword(s):  
Linear Regression ◽  
River Basin ◽  
Yangtze River ◽  
Asian Summer Monsoon ◽  
Yangtze River Basin ◽  
Early Summer ◽  
Lead Times ◽  
Seasonal Forecasts ◽  
June July ◽  
The Impact

AbstractSeasonal forecasts for Yangtze River basin rainfall in June, May–June–July (MJJ), and June–July–August (JJA) 2020 are presented, based on the Met Office GloSea5 system. The three-month forecasts are based on dynamical predictions of an East Asian Summer Monsoon (EASM) index, which is transformed into regional-mean rainfall through linear regression. The June rainfall forecasts for the middle/lower Yangtze River basin are based on linear regression of precipitation. The forecasts verify well in terms of giving strong, consistent predictions of above-average rainfall at lead times of at least three months. However, the Yangtze region was subject to exceptionally heavy rainfall throughout the summer period, leading to observed values that lie outside the 95% prediction intervals of the three-month forecasts. The forecasts presented here are consistent with other studies of the 2020 EASM rainfall, whereby the enhanced mei-yu front in early summer is skillfully forecast, but the impact of midlatitude drivers enhancing the rainfall in later summer is not captured. This case study demonstrates both the utility of probabilistic seasonal forecasts for the Yangtze region and the potential limitations in anticipating complex extreme events driven by a combination of coincident factors.

Studies on the structure and function of the mammalian testis V. Steroid metabolism by isolated interstitium and seminiferous tubules of the human testis

1974 ◽  
Vol 186 (1083) ◽  
pp. 99-120 ◽  
Keyword(s):  
Metabolic Activity ◽  
General Pattern ◽  
Steroid Metabolism ◽  
Human Testis ◽  
Clinical Aspects ◽  
Seminiferous Tubules ◽  
Bicarbonate Buffer ◽  
The Media ◽  
The Individual ◽  
And Function

Tissue was obtained from the testes of three men, two in the age range 72-75 years (subjects A and B) and one aged 25 years (subject C). Parts of the testes were dissected to obtain samples of interstitium and tubules. The individual components and whole tissue were each incubated with equimolar concentrations of [7 α - 3 H]pregnenolone and [4- 14 C]progesterone in Krebs-Ringer bicarbonate buffer pH 7.4, at 35 °C with the addition of glucose but without cofactors. Some incubations were carried out with the substrates [4- 14 C]androstenedione and [7 α - 3 H]testosterone. The media were extracted both at various time intervals throughout the incubation for a kinetic study of the metabolic activity and after a fixed interval of time at the end of the incubations. In some incubations with whole tissue both media and tissue were extracted. Both the tubules and interstitium displayed steroid metabolic activity. Qualitatively they yielded the same range of metabolites, one series leading to the formation of testosterone (∆ 5 pathway) and the other to a variety of C 21 compounds as represented by 5 α -pregnan-3 β -ol-20-one. With similar amounts of tissue there was little difference in the yields of the main products formed by the tubules as compared with those formed by the interstitium; in incubations with [4- 14 C]androstenedione the rate of conversion to [ 14 C ]testosterone by the tubules greatly exceeded that due to the interstitium. Marked differences were found in the pattern of steroid metabolism by whole tissue as compared to the general pattern presented by the corresponding tubules and interstitium. It is concluded that the seminiferous tubules and interstitium of the human testis are both capable of steroid metabolism and hence that whole tissue incubations alone are of limited value and could give rise to misleading data. Some clinical aspects of the results are briefly discussed.

scholarly journals Reproductive cycle of male wall lizard, Podarcis vaucheri (Reptilia: Sauria: Lacertidae), in Djurdjura, Northern Algeria

2017 ◽  
Author(s):  
Rabah Mamou ◽  
Elara Moudilou ◽  
Jean-Marie Exbrayat ◽  
Mansour Amroun
Keyword(s):  
Sexual Activity ◽  
Reproductive Cycle ◽  
Mixed Type ◽  
Progressive Increase ◽  
Early Summer ◽  
Seminiferous Tubules ◽  
Testis Weight ◽  
Field Observations ◽  
Testicular Weight ◽  
Resting Period

The reproductive cycle of male wall lizard Podarcis vaucheri (Boulenger, 1905) living in Djurdjura mountain, was analyzed from April till October 2014. Its seasonal mixed-type cycle was characterized by three phases: sexual activity, quiescence and recrudescence. After the emergence of lizard from hibernation an intense sexual activity was observed in spring (April, May, and June) at which the testicular weight and seminiferous tubules diameter reached their maximal values. At this period, spermiogenesis was also maximal and the spermiation allowed the release of a large quantity of spermatozoa in both the seminiferous tubules and epididymis lumen. In July, a short sexual resting period followed, during which the testes mass and seminiferous tubules diameter decreased. Spermatogonia and some primary spermatocytes were observed against the wall of seminiferous tubules. The recrudescence period (August, September and October) was characterized by a progressive increase of the testis weight and seminiferous tubules diameter. Spermatocytogenesis began in August, and spermiogenesis occurred in September and October, before the diapause period. But the presence of spermatozoids was not signaled in the epididymis lumen. Field observations and microscopic evidence of testis showed that both sexes reproduced synchronously during spring and early summer.

scholarly journals Spatial and temporal distribution of phytoplankton in Lake Skadar

2012 ◽  
Vol 64 (2) ◽  
pp. 585-595 ◽  
Author(s):  
Jelena Rakocevic
Keyword(s):  
Spatial Heterogeneity ◽  
Phytoplankton Community ◽  
General Pattern ◽  
Seasonal Succession ◽  
Temporal Distribution ◽  
Late Summer ◽  
Early Summer ◽  
Quantitative Composition ◽  
Autumn And Winter ◽  
Lake Skadar

Phytoplankton seasonal succession and spatial heterogeneity were studied in Lake Skadar from February to December 2004. A total of 167 taxa from 6 algal divisions were observed, with Bacillariophyta being best represented (52.8%). The general pattern of phytoplankton seasonal succession in Lake Skadar was: Bacillariophyta in the spring, Chlorophyta in early summer, Cyanobacteria and Chlorophyta in late summer and Bacillariophyta and Chlorophyta in autumn and winter. Distinct spatial heterogeneity was observed. The central, open part of the lake (pelagic zone) was characterized by dominant euplanktonic species, mostly diatoms, whereas the western and northwestern parts (more isolated and shallower) had higher abundance of greens and blue-greens and a higher percentage of resuspended benthic-epiphytic forms in the phytoplankton community. Comparison with former phytoplankton data showed distinct differences in terms of the qualitative and quantitative composition of the phytoplankton community of Lake Skadar, which indicates lake deterioration.

scholarly journals A biodiversity hotspot for Microgastrinae (Hymenoptera, Braconidae) in North America: annotated species checklist for Ottawa, Canada

ZooKeys ◽  
2016 ◽  
Vol 633 ◽  
pp. 1-93 ◽  
Author(s):  
Jose Fernandez-Triana ◽  
Caroline Boudreault ◽  
Joel Buffam ◽  
Ronald Maclean
Keyword(s):  
North America ◽  
General Pattern ◽  
Late Summer ◽  
The United States ◽  
Early Summer ◽  
Individual Species ◽  
Early Fall ◽  
Two Peaks ◽  
Annotated Checklist ◽  
First Time

Microgastrinae wasps (Hymenoptera, Braconidae) from the city of Ottawa and its surroundings (a 50-km radius circle, ~7,800 km2) were studied based on 1,928 specimens collected between 1894 and 2010, and housed in the Canadian National Collection of Insects. A total of 158 species from 21 genera were identified, which is by far the highest number of species ever recorded for a locality in North America. An annotated checklist of species is provided.Choerasparasitellae(Bouché, 1834) andPholetesornanus(Reinhard, 1880) are recorded for the first time in the Nearctic (previously only known from the Palearctic region),Cotesiadepressa(Viereck, 1912) is recorded for the first time in Canada (previously only known from the United States), andCotesiahemileucae(Riley, 1881) andProtapantelesphlyctaeniae(Muesebeck, 1929) are recorded for the first time in the province of Ontario. In Ottawa the most diverse genera areCotesia,Apanteles,Microplitis,Pholetesor,Microgaster, andDolichogenidea, altogether comprising 77% of the species found in the area. A total of 73 species (46%) were represented by only one or two specimens, suggesting that the inventory for Ottawa is still relatively incomplete. Seasonal distribution showed several peaks of activity, in spring, summer, and early fall. That general pattern varied for individual species, with some showing a single peak of abundance either in the summer or towards the end of the season, others species attaining two peaks, in late spring and late summer, or in early summer and early fall, and yet others attaining up to three different peaks, in spring, summer and fall. At least 72 of the Microgastrinae species from Ottawa have been previously associated with 554 species of Lepidoptera as hosts – but those historical literature records are not always reliable and in many cases are based on data from areas beyond Ottawa. Thus, our knowledge of the associations between the 158 species of microgastrine parasitoids and the caterpillars of the 2,064 species of Lepidoptera recorded from Ottawa is still very incomplete.

Ultrastructural and cytochemical studies on vitellogenesis in the trypanorhynch cestode Parachristianella trygonis Dollfus, 1946 (Eutetrarhynchidae)

2007 ◽  
Vol 52 (2) ◽  
Author(s):  
Zdzisław Świderski ◽  
Jordi Miquel ◽  
Lassad Neifar ◽  
John Mackiewicz
Keyword(s):  
Periodic Acid ◽  
General Pattern ◽  
Cell Activity ◽  
Synthetic Activity ◽  
Cell Stage ◽  
High Accumulation ◽  
Carbohydrate Synthesis ◽  
Shell Globule ◽  
Differentiation Stage ◽  
Glycogen Particles

AbstractDuring vitellogenesis in Parachristianella trygonis Trypanorhyncha, Eutetrarhynchidae) we distinguished four stages: (1) gonial or stem cell stage; (2) early differentiation stage concentrated on protein synthetic activity and shell-globule formation; (3) advanced differentiation stage with main cell activity concentrated on carbohydrate synthesis (glycogenesis) and massive glycogen storage in the form of α-glycogen rosettes and β-glycogen particles; and finally (4) mature vitellocyte stage. Early vitellocyte maturation is characterised by: (1) an increase in cell volume; (2) extensive development of large, parallel cisternae of GER that produce proteinaceous granules; (3) development of Golgi complexes engaged in packaging this material; (4) continuous enlargement of proteinaceous granules within vacuoles and their transformation into shell-globule clusters composed of heterogeneous material. Cytochemical staining with periodic acid-thiosemicarbazide-silver proteinate for polysaccharides indicated a strongly positive reaction for the presence of α-glycogen rosettes and β-glycogen particles in the advanced stage of vitellocyte maturation. Both protein synthesis for shell-globule formation and carbohydrate synthesis or glycogenesis, important storage of nutritive reserves for the developing embryos, observed during cytodifferentiation of P. trygonis vitellocytes overlap in time to some extent. Mature vitelline cells are very rich in three types of cell inclusions accumulated in large amounts in their cytoplasm: (1) shell-globule clusters, playing an important role in egg-shell formation; (2) numerous large lipid droplets, as well as a high accumulation of lipid and α-glycogen rosettes and β-glycogen particles that undoubtedly represent important nutritive reserves for the developing embryos. Despite the fact that the type of vitellogenesis and ultrastructure of the mature vitellocyte in P. trygonis appears to differ to some extent from those of three other trypanorhynch species, its general pattern and ultrastructure greatly resembles those observed in other lower cestodes. Factors that may have contributed to the qualitative and quantitative variation in lipids during vitellogenesis among the four species of Trypanorhyncha, are identified and discussed.

Assessing the environmental impact of WWTP expansion: odour nuisance and its minimization

2002 ◽  
Vol 46 (4-5) ◽  
pp. 339-346 ◽  
Author(s):  
A.G. Capodaglio ◽  
F. Conti ◽  
L. Fortina ◽  
G. Pelosi ◽  
G. Urbini
Keyword(s):  
Air Quality Modelling ◽  
Drastic Reduction ◽  
Wastewater Disposal ◽  
Slowing Down ◽  
Pollutant Concentrations ◽  
Final Design ◽  
Modelling Techniques ◽  
Total Capacity ◽  
The One ◽  
The City

As part of the effort to provide proper wastewater disposal for the City of Milan, the expansion of the WWTP located in Peschiera Borromeo has been planned and is currently under completion. The plant, sized for a population of less than 300,000, will soon treat the wastes from the south-east areas of Milan for a total capacity of over 500,000 p.e. The paper describes the approach to find a satisfactory solution of an alleged odour problem that is slowing down the completion of the plant restructuring. This included a survey of the existing plant and analysis of its final design, identification of odour emission sources and their quantification, and the examination of different alternatives for odour abatement. These were carried out using air quality modelling techniques consisting of dynamic, continuous “puff” models capable of reproducing diffusion even at very low pollutant concentrations. Several intervention hypotheses were tested and compared with the few existing regulatory norms and guidelines for odour pollution. In all but the minimum and the no-action hypotheses, proposed actions would results in a drastic reduction of nuisance effects at the receptors. Under the strongest intervention hypothesis (the one adopted by the WWTP agency), odour impact would be virtually eliminated.

Early-summer temperature variations over the past 563 yr inferred from tree rings in the Shaluli Mountains, southeastern Tibet Plateau

2014 ◽  
Vol 81 (3) ◽  
pp. 513-519 ◽  
Author(s):  
Yang Deng ◽  
Xiaohua Gou ◽  
Linlin Gao ◽  
Tao Yang ◽  
Meixue Yang
Keyword(s):  
Tree Ring ◽  
Temperature Reconstruction ◽  
Early Summer ◽  
Temperature Variability ◽  
Tibet Plateau ◽  
Tree Ring Chronology ◽  
The Pacific ◽  
June July ◽  
July Temperature ◽  
Southeastern Tibet

AbstractWe developed a tree-ring chronology (AD 1446–2008) based on 75 cores from 37Abies squamataMast. trees from the Shaluli Mountains, southeastern Tibet Plateau, China, using signal-free methods, which are ideally suited to remove or reduce the distortion introduced during traditional standardization. This chronology correlates best with regional temperatures in June–July, which allowed us to develop a June–July temperature reconstruction that explained 51.2% of the variance in the instrumental record. The reconstruction showed seven cold periods and five warm periods. Cold periods were identified from AD 1472 to 1524, 1599 to 1653, 1661 to 1715, 1732 to 1828, 1837 to 1847, 1865 to 1876 and 1907 to 1926. Warm intervals occurred from AD 1446 to 1471, 1525 to 1598, 1716 to 1731, 1848 to 1864, 1877 to 1906 and 1927 to present. The reconstruction agrees well with nearby tree-ring-based temperature reconstructions. Spatial correlation analyses suggest that our reconstructions provide information on June–July temperature variability for the southeastern Tibetan Plateau and its vicinity. Spectral analyses revealed significant peaks at 2–6, 10.7, 51.2, 102.2 and 204.8 yr. The temperature variability in this area may be affected by ENSO, the Pacific Decadal Oscillation and solar activity.

scholarly journals Spatial and Temporal Factors in Weed Interference with Newly Planted Apple Trees

HortScience ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 633-637 ◽  
Author(s):  
Ian A Merwin ◽  
John A. Ray
Keyword(s):  
Weed Control ◽  
Early Summer ◽  
Weed Suppression ◽  
Growth And Yield ◽  
Quadratic Model ◽  
Trickle Irrigation ◽  
Cumulative Yield ◽  
Yield Efficiency ◽  
June July August ◽  
June July

Temporal and spatial combinations of tree-row weed suppression treatments were evaluated during 5 years in a New York apple (Malus domestica Borkh. cv. Imperial Gala on Malling 26 rootstocks) orchard planted in Apr. 1991, and provided with trickle irrigation. Twenty-eight factorial treatment combinations [0, 2, 4, and 6 m2 weed-free areas (WFAs); and May, June, July, August, May + June, June + July, May + June + July, and June + July + August weed-free times (WFTs)] were maintained from 1991 to 1995 by postemergence paraquat herbicide applications in tree-row strips. Trunk cross-sectional area (TCA) growth and yield were monitored annually, and few differences were observed as WFA increased from 2 to 4 to 6 m2 per tree. However, WFT substantially influenced TCA, fruit production, and yield efficiency. Early summer WFTs increased TCA during the first two growing seasons, compared with late summer treatments. When trees came into production in 1993-94, yields increased as the duration of WFT increased, but where similar periods of WFT had been established later during the growing season, annual yield, cumulative yield efficiency, and the ratio of crop value to weed-control costs were all reduced. Groundcover species distribution was evaluated each year in September, and graminaceous weeds were more prevalent in the early and midsummer WFTs, while herbaceous broadleaf weeds dominated in the August treatments. A quadratic model regressing cumulative yield efficiency on WFTs grouped into 30-, 60-, and 90-day categories showed that efficiency peaked between 60 and 90 days of WFT. It appeared that timing of weed suppression may be as important as the area of suppression beneath trees in comparable apple orchards, that early summer weed control was especially important for newly planted trees, and that drip irrigation allowed reductions in the area and amount of tree-row herbicide applications, without significant losses in apple tree growth or crop value.

scholarly journals Structural and functional properties of ryanodine receptor type 3 in zebrafish tail muscle

2015 ◽  
Vol 145 (3) ◽  
pp. 173-184 ◽  
Author(s):  
Stefano Perni ◽  
Kurt C. Marsden ◽  
Matias Escobar ◽  
Stephen Hollingworth ◽  
Stephen M. Baylor ◽  
...  
Keyword(s):  
Ryanodine Receptor ◽  
Muscle Fibers ◽  
Complete Disappearance ◽  
Cell Stage ◽  
Release Channel ◽  
Functional Roles ◽  
Ec Coupling ◽  
Structural And Functional Properties ◽  
Fast Twitch ◽  
Type 3

The ryanodine receptor (RyR)1 isoform of the sarcoplasmic reticulum (SR) Ca2+ release channel is an essential component of all skeletal muscle fibers. RyR1s are detectable as “junctional feet” (JF) in the gap between the SR and the plasmalemma or T-tubules, and they are required for excitation–contraction (EC) coupling and differentiation. A second isoform, RyR3, does not sustain EC coupling and differentiation in the absence of RyR1 and is expressed at highly variable levels. Anatomically, RyR3 expression correlates with the presence of parajunctional feet (PJF), which are located on the sides of the SR junctional cisternae in an arrangement found only in fibers expressing RyR3. In frog muscle fibers, the presence of RyR3 and PJF correlates with the occurrence of Ca2+ sparks, which are elementary SR Ca2+ release events of the EC coupling machinery. Here, we explored the structural and functional roles of RyR3 by injecting zebrafish (Danio rerio) one-cell stage embryos with a morpholino designed to specifically silence RyR3 expression. In zebrafish larvae at 72 h postfertilization, fast-twitch fibers from wild-type (WT) tail muscles had abundant PJF. Silencing resulted in a drop of the PJF/JF ratio, from 0.79 in WT fibers to 0.03 in the morphants. The frequency with which Ca2+ sparks were detected dropped correspondingly, from 0.083 to 0.001 sarcomere−1 s−1. The few Ca2+ sparks detected in morphant fibers were smaller in amplitude, duration, and spatial extent compared with those in WT fibers. Despite the almost complete disappearance of PJF and Ca2+ sparks in morphant fibers, these fibers looked structurally normal and the swimming behavior of the larvae was not affected. This paper provides important evidence that RyR3 is the main constituent of the PJF and is the main contributor to the SR Ca2+ flux underlying Ca2+ sparks detected in fully differentiated frog and fish fibers.

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