Origin Of Organs Research Articles

A pragmatic comprehension of scientific and classical aspects of Rachana Sharir—A systematic review

Ayurveda, a flourishing traditional medical system renowned for its extensive knowledge, includes Rachana Sharir as a fundamental subject. Rachana Sharir Vigyan explores the anatomical aspects (Rachna) of the human body. The immense knowledge of the ancient wisdom of Ayurveda is not comprehensively described yet. The Samhitas and Vedas of Indian literature by different acharyas elaborate on how the human body evolved from a combination of Panchamahabhutas and Atma (Chetana). This review aims to elucidate the classical aspects of Rachana Sharir from Ayurvedic texts and establish correlations with contemporary scientific knowledge. Classical texts such as the Samhitas authored by various acharyas were systematically reviewed to gather insights into the origin, anatomical positions, numerical compositions, and classifications of human body parts, organs, tissues, and systems. The review reveals detailed principles and concepts from Ayurvedic literature, emphasizing contributions from Acharya Sushruta in the Sharir Sthana, particularly his meticulous descriptions of cadaveric studies and preservation techniques. Classical books explained the origins of human bodily parts, their anatomical placements, organs, tissues, systems, and more. These fall under human anatomy (Rachana Sharir), and this article explains its classical aspect with scientific and modern science linkages. In Sharir Sthana, one of Ayurveda’s main principles, cadaveric research and preservation, is beautifully illustrated by Acharya Sushruta. Ayurveda has scientific principles, logic, and subtle knowledge that we must explore to apply its gifts to humanity. This essay shows that Samhitas contains pragmatic and scientific knowledge. Ayurveda combines science and philosophy. Ayurvedic knowledge’s pragmatic and scientific usefulness beyond textual content must be explored and validated to maximize its benefits for humanity.

Testicular Germ Cell Tumours - features and prospects of the novel tumour marker microRNA-371a-3p (M371 test): a narrative review

Testicular germ cell tumours (GCTs) represent a paradigm for the usefulness of serum tumour markers in clinical management of diseases. However, the tumour markers currently in use, beta human chorionic gonadotropin (bHCG), alpha fetoprotein (AFP) and lactate dehydrogenase (LDH) are expressed in less than 50% of GCT cases. In 2011, microRNA-371a-3p (currently named M371) was suggested as a novel marker for the first time. Chemically, microRNAS represent small RNA molecules consisting of 18-24 base pairs. Physiologically, these microRNAs play a prominent role in the epigenetic control of protein biosynthesis. M371 can be measured in serum with PCR-techniques.There is high level evidence for a 90% sensitivity and >90% specificity for GCTs of the marker M371. That high diagnostic accuracy is true for both seminoma and nonseminoma but not for the histologic subgroup of teratoma. Testicular tumours of non-germ cell origin and malignant neoplasms of other organs do not express the marker. M371 involves a very short half-life of <24 hours.The test does likely involve the prospects of providing substantial aid in clinical decision-making with respect to instances where improvement of GCT management is still required. In particular, the following clinical scenarios will probably benefit from the employment of the M371 test: (1) diagnostic work-up of incidentally detected small testicular masses with decision-making in regard to testis sparing surgery or full orchiectomy (2) simplifying the follow-up of GCT patients with sparing of imaging procedures in a number of cases; (3) diagnostic evaluation of retroperitoneal lymphadenopathy upon clinical staging; (4) diagnostic evaluation of false-positive elevations of classical tumour markers (AFP, bHCG); (5) rapid appraisal of therapeutic success or failure by means of the very short half-life of M371; (6) diagnostic evaluation of postchemotherapy residual masses particularly those in seminoma patients.The discovery and development of the novel tumour marker M371 probably represents a milestone progress in the history of the clinical management of testicular GCTs.

Micro-CT data of complete metamorphosis process in Harmonia axyridis

Insect metamorphosis involves significant changes in insect internal structure and is thus a critical focus of entomological research. Investigating the morphological transformation of internal structures is vital to understanding the origins of adult insect organs. Beetles are among the most species-rich groups in insects, but the development and transformation of their internal organs have yet to be systematically documented. In this study, we have acquired a comprehensive dataset that includes 27 detailed whole-body tomographic image sets of Harmonia axyridis, spanning from the prepupal to the pupal stages. Utilizing this data, we have created intricate 3D models of key internal organs, encompassing the brain, ventral nerve cord, digestive and excretion systems, as well as the body wall muscles. These data documented the transformation process of these critical organs and correlations between the origin of adult and larval organs and can be used to enhance the understanding of holometabolous adult organ genesis and offers a valuable reference model for investigating complete metamorphosis in insects.

Obsceniškumo raiška lyčių kilmȩ aiškinančiose sakmėse

The article analyses Lithuanian aetiological tales, which explain the origin of different genders. The main aim of the study is to analyse the tales that explain the origin of male and female external genital organs, focusing on how obscenity is expressed in these stories. The main research question is whether obscene motifs are used to explain the origin of the genital organs or whether overt vulgarity is avoided. It also attempts to establish the purpose of such stories and whether their truthfulness was believed. The research uses analytical descriptive, comparative and interpretive methods, and Lithuanian tales are compared with similar variants from other countries. The analysis of the tales explaining the origins of men and women revealed that the genitals in the Lithuanian versions of the tales are not associated with a reproductive function but are only a kind of body accessory. The tales mention that humans were able to reproduce successfully even before the creation of the sex organs. The obscenity in the tales about the origin of the sexes is only implicit and conditional. In the variants analysed, there is not a single word that is classified as a swear word, and there are almost no euphemistic names for the genital organs either. The explanation of the origin of the male sex is based on the comparison of similar objects (a banana, a twig, a ball of clay, a long thread with a skewer in the crotch), while the origin of the female sex is motivated by destruction (the crotch has ruptured or been punctured) or by lack (the thread for the belly has been missing). In those tales, in which the origin of women is linked to the activity of a mythical being – God or the devil –, the attitude towards women is usually mocking and belittling.

A New Gnetalean Macrofossil from the Mid-Jurassic Daohugou Formation.

Macrofossil evidence has demonstrated a first radiation of gnetophytes in the Early Cretaceous. However, the origin of the diversity of gnetophytes remains ambiguous because gnetalean macrofossils have rarely been reported from pre-Cretaceous strata. Here, we report a new putative gnetalean macrofossil reproductive shoot which possesses opposite phyllotaxy, long linear leaves more or less decurrent and having a prominent midvein and pedicled ovoid-ellipsoid and longitudinally striated chlamydosperms. Our new fossil is different from other known gnetalean macrofossils in the linear-lanceolate leaves with a midvein and pedicled chlamydosperms. As a result, we describe this new macrofossil reproductive shoot as new to science, i.e., Daohugoucladus sinensis gen. et sp. nov. Our new macrofossil displays additional morphological characters distinct from other known Mesozoic and modern gnetalean species and provides additional evidence of the origin and early evolution of female reproductive organs of gnetophytes.

Transcriptional Analysis of the Endostyle Reveals Pharyngeal Organ Functions in Ascidian.

The endostyle is a pharyngeal organ with an opening groove and cilia in invertebrate chordates (amphioxus and ascidian) and cyclostomate (lamprey), serving as a filter-feeding tract and thyroid-secreting location. Emerging evidence implies its complex cellular composition and potentially versatile functions. Multiple cell types in the endostyle have been thought to be progenitors of complex organs in advanced vertebrates. To describe the expression profile and the potential functions, bulk RNA sequencing on the endostyle in ascidian Styela clava was conducted and distinct markers were selected by multileveled comparative analysis. Transcriptional data assay and qRT-PCR-verified results showed the regional expression patterns of Hox genes in the longitudinal axis. Organ-specific markers of the endostyle was proposed by comparing expression with the main organs of the ascidian. A cross-species transcriptional profile projection between the endostyle and organs from Danio rerio and Homo sapiens indicates a robust homogenous relationship to the thyroid and digestive system of the endostyle. The high similarity between the endostyle and the head kidney in zebrafish/the bone marrow in human implies uniquely profound functions of the pharyngeal organ in proto-vertebrates. Our result revealed that the transcriptional profile of the human parathyroid gland was similar to the ascidian endostyle, indicating the evolutionary origin of vertebrate hormone secretion organs.

Establishing a missing person DNA Biobank as a form of human rights protection.

Nowadays, organ transplantation is considered an established medical practice that, every year, improves the quality of life of thousands of patients. However, the increasing demands for kidney transplantation are in contrast with the global lack of organs. The imbalance between supply and demand for organs has created the basis for a highly profitable black market, placing illicit organ trafficking in the broader context of human trafficking. Currently, thanks to the advancements of the analytical techniques used in laboratories, forensic genetics is able to discriminate the geographical origin of genetically distinct populations. The recent availability of genetic data regarding many populations of the world and the concomitant development of technologies and methodologies that are appropriate for the study of panels of STRs and SNPs are fundamental resources in this direction. This type of analyses, together with the creation of missing person DNA databases, may be used in cases of dubious origin of organs or in transplantation cases in which clear and comprehensive medical records of patients and donors are not available. It can also establish a scientific tool useful to contrast the illegal traffic of human kidneys. In this article, we will discuss biological and ethical aspects of this interesting perspective.

Molecular evidence for a single origin of ultrafiltration-based excretory organs

Excretion is an essential physiological process, carried out by all living organisms, regardless of their size orcomplexity.1-3 Both protostomes (e.g., flies and flatworms) and deuterostomes (e.g., humans and sea urchins) possess specialized excretory organs serving that purpose. Those organs exhibit an astonishing diversity, ranging from units composed of just few distinct cells (e.g., protonephridia) to complex structures, built by millions of cells of multiple types with divergent morphology and function (e.g., vertebrate kidneys).4,5 Although some molecular similarities between the development of kidneys of vertebrates and the regeneration of the protonephridia of flatworms have been reported,6,7 the molecular underpinnings of the development of excretory organs have never been systematically studied in a comparative context.4 Here, we show that a set of transcription factors (eya, six1/2, pou3, sall, lhx1/5, and osr) and structural proteins (nephrin, kirre, and zo1) is expressed in the excretory organs of a phoronid, brachiopod, annelid, onychophoran, priapulid, and hemichordate that represent major protostome lineages and non-vertebrate deuterostomes. We demonstrate that the molecular similarity observed in the vertebrate kidney and flatworm protonephridia6,7 is also seen in the developing excretory organs of those animals. Our results show that all types ofultrafiltration-based excretory organs are patterned by a conserved set of developmental genes, an observation that supports their homology. We propose that the last common ancestor of protostomes and deuterostomes already possessed an ultrafiltration-based organ that later gave rise to the vast diversity of extant excretory organs, including both proto- and metanephridia.

Nepenthes × ventrata Transcriptome Profiling Reveals a Similarity Between the Evolutionary Origins of Carnivorous Traps and Floral Organs.

The emergence of the carnivory syndrome and traps in plants is one of the most intriguing questions in evolutionary biology. In the present study, we addressed it by comparative transcriptomics analysis of leaves and leaf-derived pitcher traps from a predatory plant Nepenthes ventricosa × Nepenthes alata. Pitchers were collected at three stages of development and a total of 12 transcriptomes were sequenced and assembled de novo. In comparison with leaves, pitchers at all developmental stages were found to be highly enriched with upregulated genes involved in stress response, specification of shoot apical meristem, biosynthesis of sucrose, wax/cutin, anthocyanins, and alkaloids, genes encoding digestive enzymes (proteases and oligosaccharide hydrolases), and flowering-related MADS-box genes. At the same time, photosynthesis-related genes in pitchers were transcriptionally downregulated. As the MADS-box genes are thought to be associated with the origin of flower organs from leaves, we suggest that Nepenthes species could have employed a similar pathway involving highly conserved MADS-domain transcription factors to develop a novel structure, pitcher-like trap, for capture and digestion of animal prey during the evolutionary transition to carnivory. The data obtained should clarify the molecular mechanisms of trap initiation and development and may contribute to solving the problem of its emergence in plants.

Using the Past to Understand the Present: Coping with Natural and Anthropogenic Noise

ABSTRACT Anthropogenic noise has received significant attention in recent years, and researchers have highlighted the ways in which animals might deal with these noise sources. However, much of our understanding of animal responses to this novel source of background acoustics lacks an evolutionary perspective. Natural sources of noise predate the origin of hearing organs in animals. Therefore, it is unlikely that animals have only recently evolved strategies to cope with anthropogenic noise de novo but, rather, already have preexisting coping mechanisms, because of countless generations of evolution within a naturally noisy world, on which contemporary selection is now likely acting. We review strategies to cope with natural sources of noise and suggest a more quantitative and mechanistic understanding of how particular characteristics of noise have shaped animal populations and communities in the past, enabling us to predict the effects that novel sources of noise will have on the future.

ANATOMICAL MODELING OF FETUS AND NEWBORN PALM STRUCTURES

Numerous anomalies manifested in clinical practice, in most cases, can be explained only on the basis of clarifying the origin and interaction of organs and structures, which over time acquire their characteristic forms, having studied their unusual topography and deeply understanding the corresponding embryonic phenomena. A detailed study of the anatomy of the hand is necessary for a correct under-standing of the pathways of the spread of purulent-inflammatory processes and the development of rational methods of surgical treatment. The prognostication models created to foresee standard morphometric parameters of a palm within a perinatal ontogenesis period are: for the length of a palm = β0+ 0.042 х parietal-calcaneal lengths of a fetus, where β0:= 3.587 during the 4th month of gestation; 5.562 = 5th month; 4.071 = 6th month; 4.840 = 7th month; 6.881 = 8th month; 5.624 = 9th month; 5.448 = 10th month; 5.765 = neonates; for the width of a palm = β0+ 0.038 х parietal-calcaneal length of a fetus, where β0= 2,887 for the 4th month of fetal age; 4.341 = 5th month; 2.638 = 6th month; 3.324 = 7th month; 3.548 = 8th month; 1.714 = 9th month; 1.814 = 10th month; 3.231 = neonates. The proposed models of standard morphometric parameters of a palmar aponeurosis in the perinatal ontogenesis period are the following: for its length – the length of a palmar aponeurosis = β0+ 0.022 х parietal-calcaneal length of a fetus, where β0= 3.531 for the 4th month of the gestational age; 6.532 = 5th month; 6.851 = 6th month; 6.526 = 7th month; 7.583 = 8th month; 7.044 = 9th month; 6.964 = 10th month; 7.968 = neonates; for the width – the width of a palmar aponeurosis = β0+ 0.018 х parietal-calcaneal length of a fetus, where β0= 2.624 within the 4th month of a fetus age; 5.431 = 5th age; 3.701 = 6th age; 4.233 = 7th age; 4.121 = 8th month; 3.602 = 9th age; 3.956 = 10th month; 4.881 = neonates.

Light-sheet fluorescence imaging charts the gastrula origin of vascular endothelial cells in early zebrafish embryos

It remains challenging to construct a complete cell lineage map of the origin of vascular endothelial cells in any vertebrate embryo. Here, we report the application of in toto light-sheet fluorescence imaging of embryos to trace the origin of vascular endothelial cells (ECs) at single-cell resolution in zebrafish. We first adapted a previously reported method to embryo mounting and light-sheet imaging, created an alignment, fusion, and extraction all-in-one software (AFEIO) for processing big data, and performed quantitative analysis of cell lineage relationships using commercially available Imaris software. Our data revealed that vascular ECs originated from broad regions of the gastrula along the dorsal–ventral and anterior–posterior axes, of which the dorsal–anterior cells contributed to cerebral ECs, the dorsal–lateral cells to anterior trunk ECs, and the ventral–lateral cells to posterior trunk and tail ECs. Therefore, this work, to our knowledge, charts the first comprehensive map of the gastrula origin of vascular ECs in zebrafish, and has potential applications for studying the origin of any embryonic organs in zebrafish and other model organisms.

A Literature Review on the Role of TBX5 in Expression and Progression of Lung Cancer: Current Perspectives

T-box转录因子（T-box transcription factor gene, TBX）基因涉及器官的发生，TBX5在人的正常心脏和肺组织中表达水平最高。TBX5的缺乏可能导致胸廓发育畸形和膈肌发育异常，其异位表达和过表达会诱导细胞凋亡和抑制细胞生长。既往研究发现了TBX5在食管腺癌、胃癌、结肠癌和乳腺癌的发生和发展中的潜在作用。我们对TBX2亚家族的基因表达和预后之间的关系进行了综述，同时探究TBX5在调控肺癌发生发展机制中的研究进展。虽然TBX5和肺癌发生之间的关系尚不明确，不过TBX5可以显著抑制人体内肿瘤生长，其表达水平和肺癌的进展呈现负相关。由此，TBX5的基因表达水平和甲基化程度是潜在的表证肺癌增殖和转移的生物标志物，具有作为肺癌治疗靶点的潜力。

Genome-Wide Identification and Transcriptomic Analysis of MicroRNAs Across Various Amphioxus Organs Using Deep Sequencing.

Amphioxus is the closest living invertebrate proxy of the vertebrate ancestor. Systematic gene identification and expression profile analysis of amphioxus organs are thus important for clarifying the molecular mechanisms of organ function formation and further understanding the evolutionary origin of organs and genes in vertebrates. The precise regulation of microRNAs (miRNAs) is crucial for the functional specification and differentiation of organs. In particular, those miRNAs that are expressed specifically in organs (OSMs) play key roles in organ identity, differentiation, and function. In this study, the genome-wide miRNA transcriptome was analyzed in eight organs of adult amphioxus Branchiostoma belcheri using deep sequencing. A total of 167 known miRNAs and 23 novel miRNAs (named novel_mir), including 139 conserved miRNAs, were discovered, and 79 of these were identified as OSMs. Additionally, analyses of the expression patterns of eight randomly selected known miRNAs demonstrated the accuracy of the miRNA deep sequencing that was used in this study. Furthermore, potentially OSM-regulated genes were predicted for each organ type. Functional enrichment of these predicted targets, as well as further functional analyses of known OSMs, was conducted. We found that the OSMs were potentially to be involved in organ-specific functions, such as epidermis development, gonad development, muscle cell development, proteolysis, lipid metabolism, and generation of neurons. Moreover, OSMs with non–organ-specific functions were detected and primarily include those related to innate immunity and response to stimuli. These findings provide insights into the regulatory roles of OSMs in various amphioxus organs.

Active mode of excretion across digestive tissues predates the origin of excretory organs.

Most bilaterian animals excrete toxic metabolites through specialized organs, such as nephridia and kidneys, which share morphological and functional correspondences. In contrast, excretion in non-nephrozoans is largely unknown, and therefore the reconstruction of ancestral excretory mechanisms is problematic. Here, we investigated the excretory mode of members of the Xenacoelomorpha, the sister group to Nephrozoa, and Cnidaria, the sister group to Bilateria. By combining gene expression, inhibitor experiments, and exposure to varying environmental ammonia conditions, we show that both Xenacoelomorpha and Cnidaria are able to excrete across digestive-associated tissues. However, although the cnidarian Nematostella vectensis seems to use diffusion as its main excretory mode, the two xenacoelomorphs use both active transport and diffusion mechanisms. Based on these results, we propose that digestive-associated tissues functioned as excretory sites before the evolution of specialized organs in nephrozoans. We conclude that the emergence of a compact, multiple-layered bilaterian body plan necessitated the evolution of active transport mechanisms, which were later recruited into the specialized excretory organs.

Comparative Transcriptome Analyses Reveal the Role of Conserved Function in Electric Organ Convergence Across Electric Fishes.

The independent origins of multiple electric organs (EOs) of fish are fascinating examples of convergent evolution. However, comparative transcriptomics of different electric fish lineages are scarce. In this study, we found that the gene expression of EOs and skeletal muscles from three lineages (Mormyroidea, Siluriformes, and Gymnotiformes) tended to cluster together based on the species of origin, irrespective of the organ from which they are derived. A pairwise comparison of differentially expressed genes (DEGs) revealed that no less than half of shared DEGs exhibited parallel expression differentiation, indicating conserved directionality of differential expression either in or between lineages, but only a few shared DEGs were identified across all focal species. Nevertheless, the functional enrichment analysis of DEGs indicated that there were more parallel gene expression changes at the level of pathways and biological functions. Therefore, we may conclude that there is no parallel evolution of the entire transcriptomes of EOs among different lineages. Further, our results support the hypothesis that it is not different genes but conserved biological functions that play a crucial role in the convergence of complex phenotypes. This study provides insight into the genetic basis underlying the EO convergent evolution; however, more studies in different cases will be needed to demonstrate whether this pattern can be extended to other cases to derive a general rule for convergent evolution.

The Role of Heritable Tumors in Evolution of Development: a New Theory of Carcino-evo-devo.

The hypothesis of evolution by tumor neofunctionalization (the "main hypothesis") describes the possible role of hereditary tumors in evolution. The present article examines the relationship of the main hypothesis to other biological theories. As shown in this paper, the main hypothesis does not contradict to the existing biological theories, but fills the lacunas between them and explains some unexplained (or not completely understood) questions. Common features of embryonic development and tumorigenesis are described by several recognized theories. Similarities between normal development and tumorigenesis suggest that tumors could participate in the evolution of ontogenesis and in the origin of new cell types, tissues and organs. A wide spectrum of non-trivial explanations and non-trivial predictions in different fields of biology, suggested by the main hypothesis, is an indication of its fundamental nature and the potential to become a new biological theory, a theory of the role of tumors in evolution of development, or carcino-evo-devo.

The molecular basis of pelvic brooding, a novel reproductive strategy

Event Abstract Back to Event The molecular basis of pelvic brooding, a novel reproductive strategy Leon Hilgers1*, Arne W. Nolte2, Tobias Spanke1, Jana M. Flury1, Fabian Herder1, Bernhard Misof1 and Julia Schwarzer1 1 Zoological Research Museum Alexander Koenig (LG), Germany 2 University of Oldenburg, Germany Although evolutionary innovations have fascinated evolutionary biologists for more than 150 years, our understanding of their molecular underpinnings is still in its infancy. Novel reproductive strategies represent particularly promising models to study evolutionary innovation, because they rely on complex sets of behavioral, physiological and anatomical adaptations and sometimes even involve the origin of novel organs. Sulawesi ricefishes (Actinopterygii: Adrianichthyidae) exhibit a novel reproductive strategy that is referred to as pelvic brooding 1–3. Females of pelvic brooding species carry their clutch in a ventral concavity, covered by their pelvic fins, until the fry hatches. The eggs are connected to the female by attaching filaments, which are anchored inside the abdomen by a unique structure, called the plug 4. Furthermore, ovulation is delayed in pelvic brooders as long as eggs are attached and accelerated in case eggs are prematurely lost 5. Thus, pelvic brooding likely relies on several adaptations such as modified fins, shortened ribs, altered timing of ovulation and a novel plug structure 2–5. Despite its apparent complexity, pelvic brooding likely evolved from oviparous ancestors in at least two lineages 6. While the potentially repeated and likely recent origin of pelvic brooding makes it a promising system to study evolutionary innovations, its molecular basis remained so far unexplored. Here we use tissue-specific transcriptomes of brooding and non-brooding Oryzias eversi to gain insight into the genetic basis of pelvic brooding. We combine differential expression and functional enrichment analyses to shed light on pelvic-brooding related gene regulation and dominant molecular functions in different tissues including the novel plug structure. To this end, brooding females of O. eversi were separated and tissues harvested during mid-brooding and after brooding was completed when fish can, in principle, spawn again. Here we show that egg-carrying is associated with significant tissue-specific changes in gene expression. Changes in gene expression are strongest in the ovary with 47 differentially expressed (DE) genes (false discovery rate (FDR) ≤ 0.001), followed by the papilla (18 DE genes) and least severe in the skin (3 DE genes), which served as a reference tissue. Gene expression in the ovary is mostly down-regulated during brooding, matching suppressed ovulation during egg-carrying. Although gene expression between the dermally derived structures papilla and skin is very similar, it becomes more distinct during brooding. These findings in combination with significant gene expression changes in the papilla corroborate the morphology-based hypothesis that the genital papilla may play a role in pelvic brooding. Furthermore, the plug, which is a novel tissue that forms after spawning, exhibits remarkably distinct gene expression compared to the other tissues. Genes with plug-specific expression (overexpressed against all other tissues, FDR ≤ 10-10) are significantly enriched in genes with functions in immunity and include genes that also have important functions in mammalian placentas. Hence, our results indicate an important role for the immune system in plug formation during pelvic brooding and substantiate some parallels of pelvic-brooding with mammalian pregnancy and placentation. Future studies will build upon this work to investigate to what extend tissue-specific changes in gene expression during brooding are based on regulatory evolution, whether or not pelvic brooding has evolved in parallel and if so, to what extend similar molecular mechanisms underly its repeated evolution. In conclusion, this study sheds first light on the molecular basis of pelvic brooding and paves the way for a better understanding of the genetic basis of novel reproductive strategies and ultimately evolutionary innovations.

Floral reversion and first record of pseudovivipary in some species of Poaceae

ABSTRACT This contribution constitutes the first report of floral reversion and occurrence of pseudovivipary in Paspalum ceresia (Kuntze) Chase, P. stellatum Humb. & Bonpl. ex Flugge and Thysanolaena latifolia (Roxb. ex Hornem.) Honda. Observations were made in material kept under cultivation in Buenos Aires (Argentina) since March 2001. Proliferating spikelets are described and illustrated, and some implications in the origin of spikelet organs are discussed. An up to date table including the genera of Poaceae where this phenomenon has been documented is also provided.

History and contemporary significance of the Rhynie cherts-our earliest preserved terrestrial ecosystem.

The Rhynie cherts Unit is a 407 million-year old geological site in Scotland that preserves the most ancient known land plant ecosystem, including associated animals, fungi, algae and bacteria. The quality of preservation is astonishing, and the initial description of several plants 100 years ago had a huge impact on botany. Subsequent discoveries provided unparalleled insights into early life on land. These include the earliest records of plant life cycles and fungal symbioses, the nature of soil microorganisms and the diversity of arthropods. Today the Rhynie chert (here including the Rhynie and Windyfield cherts) takes on new relevance, especially in relation to advances in the fields of developmental genetics and Earth systems science. New methods and analytical techniques also contribute to a better understanding of the environment and its organisms. Key discoveries are reviewed, focusing on the geology of the site, the organisms and the palaeoenvironments. The plants and their symbionts are of particular relevance to understanding the early evolution of the plant life cycle and the origins of fundamental organs and tissue systems. The Rhynie chert provides remarkable insights into the structure and interactions of early terrestrial communities, and it has a significant role to play in developing our understanding of their broader impact on Earth systems.This article is part of a discussion meeting issue 'The Rhynie cherts: our earliest terrestrial ecosystem revisited'.