scholarly journals Embryo sac haustorium in Dryas octopetala L. (Rosaceae)

2014 ◽  
Vol 56 (2) ◽  
pp. 209-214 ◽  
Author(s):  
Romana Czapik
Keyword(s):  
Embryo Sac ◽  
First Record ◽  
Central Cell ◽  
Characteristic Shape ◽  
Dense Cytoplasm ◽  
Dryas Octopetala ◽  
Tatra Mts

The embryo sac haustorium found in <em>Dryas octopetala</em> L. from the Tatra Mts is the first record of its occurrence in <em>Rosaceae</em>. At the eight-nucleate stage of the embryo sac, the antipodal end of the central cell began to grow into a narrow caecum filled with dense cytoplasm and elongated in the chalazal direction leaving the three antipodals in situ. The haustorium enlarged and lost its characteristic shape after the period of fertilization. Finally, the embryo sac occupied almost the whole length of the ovule. Situated at its chalazal end there was either dense cytoplasm with a group of endosperm nuclei or dense, grainy cytoplasm only, if fertilization had not taken place.

scholarly journals Pelagic deep-sea fauna observed on video transects in the southern Norwegian Sea

Polar Biology ◽  
2021 ◽  
Author(s):  
Philipp Neitzel ◽  
Aino Hosia ◽  
Uwe Piatkowski ◽  
Henk-Jan Hoving
Keyword(s):  
First Record ◽  
Observation System ◽  
In Situ Observation ◽  
Norwegian Sea ◽  
Video Recordings ◽  
In Situ Observations ◽  
Abundance And Distribution ◽  
Oceanic Food Webs ◽  
Deep Sea Fauna

AbstractObservations of the diversity, distribution and abundance of pelagic fauna are absent for many ocean regions in the Atlantic, but baseline data are required to detect changes in communities as a result of climate change. Gelatinous fauna are increasingly recognized as vital players in oceanic food webs, but sampling these delicate organisms in nets is challenging. Underwater (in situ) observations have provided unprecedented insights into mesopelagic communities in particular for abundance and distribution of gelatinous fauna. In September 2018, we performed horizontal video transects (50–1200 m) using the pelagic in situ observation system during a research cruise in the southern Norwegian Sea. Annotation of the video recordings resulted in 12 abundant and 7 rare taxa. Chaetognaths, the trachymedusaAglantha digitaleand appendicularians were the three most abundant taxa. The high numbers of fishes and crustaceans in the upper 100 m was likely the result of vertical migration. Gelatinous zooplankton included ctenophores (lobate ctenophores,Beroespp.,Euplokamissp., and an undescribed cydippid) as well as calycophoran and physonect siphonophores. We discuss the distributions of these fauna, some of which represent the first record for the Norwegian Sea.

Early events in the embryo sac after intraspecific and interspecific pollinations in Rhododendron kawakamii and R. retusum

1986 ◽  
Vol 64 (2) ◽  
pp. 282-291 ◽  
Author(s):  
V. Kaul ◽  
J. L. Rouse ◽  
E. G. Williams
Keyword(s):  
Seed Set ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Interspecific Crosses ◽  
Primary Endosperm Nucleus ◽  
Kalmia Latifolia ◽  
Taxonomic Grouping ◽  
Similarities And Differences ◽  
Normal Fertilization

Early events in the embryo sac of Rhododendron kawakamii and R. retusum have been studied after compatible self-pollinations and eight interspecific crosses, using sectioned ovaries, pistil squashes, and seed-set data. Ovules of Rhododendron kawakamii and R. retusum are anatropous, unitegmic, and tenuinucellate, with a typical eight-nucleate, seven-celled embryo sac. Fertilization normally occurs 4–5 days after pollination. The zygote lays down a callose wall but remains undivided during the first 13–15 days after pollination. The primary endosperm nucleus divides soon after fertilization, and development is cellular ab initio. Crosses of R. kawakamii (♂) with R. santapaui and R. retusum and crosses of R. retusum (♂) with R. kawakamii, R. santapaui, R. ovatum, and R. tashiroi showed apparently normal fertilization in a majority of ovules entered by pollen tubes. In crosses of R. kawakamii (♂) with R. quadrasianum and Kalmia latifolia entry of pollen tubes into ovules was delayed and frequently abnormal. Apart from compatible self-pollinations of R. kawakamii an R. retusum, only the cross of R. kawakamii (♂) with R. santapaui produced healthy seedlings. Of the remaining seven interspecific crosses only three showed significant embryo development in control pistils left to mature in situ. Similarities and differences in the breeding behaviour of R. kawakamii and R. retusum are discussed with reference to their taxonomic grouping within subsection Pseudovireya.

scholarly journals First record of cuttlefish egg-deposition at an in situ coral nursery

2018 ◽  
Vol 20 (1) ◽  
pp. 9-10 ◽  
Author(s):  
Shu Qin SAM ◽  
Daisuke TAIRA ◽  
Chin Soon Lionel NG ◽  
Tai Chong TOH ◽  
Loke Ming CHOU
Keyword(s):  
First Record ◽  
Egg Deposition

The first North American record of Carinodens belgicus (Squamata, Mosasauridae) and correlation with the youngest in situ examples from the Maastrichtian type area: palaeoecological implications

2013 ◽  
Vol 92 (2-3) ◽  
pp. 145-152 ◽  
Author(s):  
E.W.A. Mulder ◽  
P. Formanoy ◽  
W.B. Gallagher ◽  
J.W.M. Jagt ◽  
A.S. Schulp
Keyword(s):  
North America ◽  
Atlantic Ocean ◽  
North American ◽  
Atlantic Coast ◽  
First Record ◽  
Type Area

AbstractFour recently collected tooth crowns of the rare latest Cretaceous (late Maastrichtian) durophagous mosasaur Carinodens belgicus are discussed; the first record from the Atlantic coast of North America (Maryland), and three additional in situ examples from the Maastrichtian type area in the southeast Netherlands and northeast Belgium. Also presented are an updated overview of the material recorded to date, and a discussion of the palaeobiogeographical and palaeoenvironmental distribution of the genus. Towards the end of the Cretaceous, Carinodens appears to have been successful in exploiting the margins of both the proto-Atlantic Ocean and the Tethyan Realm.

scholarly journals Polymorphy and extinction of the Late Cretaceous burrowing shrimp Protocallianassa faujasi and first record of the genera Corallianassa and Calliax (Crustacea, Decapoda, Thalassinoidea) from the Cretaceous

2001 ◽  
Vol 70 (2) ◽  
pp. 85-98 ◽  
Author(s):  
Krista Swen ◽  
René H.B. Fraaije ◽  
Gijsbert J. van der Zwaan
Keyword(s):  
New Species ◽  
First Record ◽  
Suspension Feeding ◽  
Feeding Mode ◽  
Male And Female ◽  
Immature Male ◽  
Type Area ◽  
Mode Of Life ◽  
Burrow Morphology

A biometric study of chelae of the burrowing shrimp Protocallianassa faujasi ( Desmarest, 1822), from the late Maastrichtian of the Maastrichtian type area, The Netherlands, has revealed three morphotypes. These types are interpreted as sexual dimorphs (male and female) and earliest ecdysis stages (immature male). Among the studied material are fifteen specimens of a new Cretaceous callianassid, Corallianassa acucurvata new species, one specimen provisionally assigned to the genus Calliax and a callianassid from the Danian. Burrows preserving callianassid chelae in situ are discussed. Based on burrow morphology a suspension feeding mode of life for P.faujasi is inferred, whereas C. acucurvata n. sp. probably was an active omnivorous analogue of its closest Recent relatives. The extinction of P. faujasi in the Meerssen Member appears to correspond to the increase in seagrass vegetation. The Protocallianassa-Corallianassa faunal changeover took place about 100,000 yrs before the K/T boundary in this region.

Development of a Heat-Inducible Gene Expression System Using Female Gametophytes of Arabidopsis thaliana

2019 ◽  
Vol 60 (11) ◽  
pp. 2564-2572 ◽  
Author(s):  
Dukhyun Hwang ◽  
Satomi Wada ◽  
Azusa Takahashi ◽  
Hiroko Urawa ◽  
Yasuhiro Kamei ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Expression System ◽  
Embryo Sac ◽  
Gene Induction ◽  
Central Cell ◽  
Egg Cell ◽  
Dominant Negative Mutant ◽  
Nucleate Cell ◽  
Recombination System ◽  
Induction System

Abstract Female gametophyte (FG) is crucial for reproduction in flowering plants. Arabidopsis thaliana produces Polygonum-type FGs, which consist of an egg cell, two synergid cells, three antipodal cells and a central cell. Egg cell and central cell are the two female gametes that give rise to the embryo and surrounding endosperm, respectively, after fertilization. During the development of a FG, a single megaspore produced by meiosis undergoes three rounds of mitosis to produce an eight-nucleate cell. A seven-celled FG is formed after cellularization. The central cell initially contains two polar nuclei that fuse during female gametogenesis to form the secondary nucleus. In this study, we developed a gene induction system for analyzing the functions of various genes in developing Arabidopsis FGs. This system allows transgene expression in developing FGs using the heat-inducible Cre-loxP recombination system and FG-specific embryo sac 2 (ES2) promoter. Efficient gene induction was achieved in FGs by incubating flower buds and isolated pistils at 35�C for short periods of time (1–5 min). Gene induction was also induced in developing FGs by heat treatment of isolated ovules using the infrared laser-evoked gene operator (IR-LEGO) system. Expression of a dominant-negative mutant of Sad1/UNC84 (SUN) proteins in developing FGs using the gene induction system developed in this study caused defects in polar nuclear fusion, indicating the roles of SUN proteins in this process. This strategy represents a new tool for analyzing the functions of genes in FG development and FG functions.

scholarly journals The significance of anthropochory in Hercinothrips femoralis (Thysanoptera: Thripidae) – Short Communication

2019 ◽  
Vol 55 (No. 4) ◽  
pp. 261-264
Author(s):  
Martin Štefánik ◽  
Martina Zvaríková ◽  
Rudolf Masarovič ◽  
Peter Fedor
Keyword(s):  
Crucial Role ◽  
Short Communication ◽  
First Record ◽  
Passive Transport ◽  
Preliminary Results ◽  
Introduction Pathway ◽  
High Tatra Mts ◽  
Tatra Mts

After the first record of the banded greenhouse thrips, Hercinothrips femoralis (Reuter, 1891) in Slovakia in 2008, a peculiar occurrence in an extreme subalpine environment of Podbanské (High Tatra Mts.), Slovakia, during the summer of the same year was observed. Since this species of exotic thrips is known to be almost sedentary, the mode of dispersal was hypothesized to be related to passive transport via weather currents. According to our observations of unintentional dispersal a test was conducted to research a previously unidentified introduction pathway of this species. Our preliminary results show that passive transport by humans plays a crucial role in the dispersal of H. femoralis.

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