Similar Appendages Research Articles

Early developmental stages of a Lower Ordovician marrellid from Morocco suggest simple ontogenetic niche differentiation in early euarthropods

Early developmental stages of euarthropods are exceptionally rare in the fossil record. This hampers our understanding of the biology, phylogeny, and development of this extremely diverse metazoan group. Herein, we use classical paleontological methods in combination with synchrotron X-ray microtomography to explore the morphology in ca. 480 million-year-old early developmental stages of the Lower Ordovician Fezouata Shale marrellid euarthropod. These stages range between 3.8 and 5.3 mm in length and are characterized by three distinct pairs of gently curved spines that projects from the head shield. The first pair of cephalic appendages are represented by uniramous antenullae of a sensory function. The second pair of cephalic appendages is robust, and had an anchoring or stabilizing function. The third cephalic appendage pair is composed of long cylindrical podomeres and was used for walking. The trunk appendages are biramous and consist of an endopod and a lamellate exopod. Two anterior trunk endopods are composed of long slender podomeres and were used for walking, while the more posterior trunk endopods bear robust endites and associated setae and were used for food gathering. The trunk of the earliest developmental stages is composed of thirteen segments, in contrast to more than 22 segments in the adult trunk. The similar appendage morphology and differentiation along the body is evident in adult individuals of the Fezouata marrellid, suggesting these different developmental stages shared similar methods of locomotion and food processing. Given that adults and juveniles are often preserved in the same or nearby sites, the niche differentiation between these life stages would be the result of the absolute smaller appendage size in immature stages compared to larger adults, effectively differentiating the size of food resources consumed by each. In addition, the delicate setae present in the posterior trunk appendages of early developmental stages might have been used to capture smaller food particles. This simple mode of ontogenetic niche differentiation might have been common in the early diverging euarthropod groups.

Dual Functions of labial Resolve the Hox Logic of Chelicerate Head Segments.

Despite an abundance of gene expression surveys, comparatively little is known about Hox gene function in Chelicerata. Previous investigations of paralogs of labial (lab) and Deformed (Dfd) in a spider have shown that these play a role in tissue maintenance of the pedipalp segment (lab-1) and in patterning the first walking leg identity (Dfd-1), respectively. However, extrapolations of these data across chelicerates are hindered by the existence of duplicated Hox genes in arachnopulmonates (e.g., spiders and scorpions), which have resulted from an ancient whole genome duplication (WGD) event. Here, we investigated the function of the single-copy ortholog of lab in the harvestman Phalangium opilio, an exemplar of a lineage that was not subject to this WGD. Embryonic RNA interference against lab resulted in two classes of phenotypes: homeotic transformations of pedipalps to chelicerae, as well as reduction and fusion of the pedipalp and leg 1 segments. To test for combinatorial function, we performed a double knockdown of lab and Dfd, which resulted in a homeotic transformation of both pedipalps and the first walking legs into cheliceral identity, whereas the second walking leg is transformed into a pedipalpal identity. Taken together, these results elucidate a model for the Hox logic of head segments in Chelicerata. To substantiate the validity of this model, we performed expression surveys for lab and Dfd paralogs in scorpions and horseshoe crabs. We show that repetition of morphologically similar appendages is correlated with uniform expression levels of the Hox genes lab and Dfd, irrespective of the number of gene copies.

COX2-ATP Synthase Regulates Spine Follicle Size in Hedgehogs.

Skin evolves essential appendages with adaptive patterns that synergistically insulate the body from environmental insults. How similar appendages in different animals generate diversely-sized appendages remain elusive. Here we used hedgehog spine follicles and mouse hair follicles as models to investigate how similar follicles form in different sizes postnatally. Histology and immunostaining show that the spine follicles have a significantly greater size than the hair follicles. By RNA-sequencing analysis, we found that ATP synthases are highly expressed in hedgehog skin compared to mouse skin. Inhibition of ATP synthase resulted in smaller spine follicle formation during regeneration. We also identified that the mitochondrial gene COX2 functions upstream of ATP synthase that influences energy metabolism and cell proliferation to control the size of the spine follicles. Our study identified molecules that function differently in forming diversely-sized skin appendages across different animals, allowing them to adapt to the living environment and benefit from self-protection.

Transitions in functional morphology from "large branchiopods" to Cladocera: Video and confocal microscopic studies of Cyclestheria hislopi (Cyclestherida) and Sida crystallina (Cladocera: Ctenopoda).

Great diversity is found in morphology and functionality of arthropod appendages, both along the body axis of individual animals and between different life-cycle stages. Despite many branchiopod crustaceans being well known for displaying a relatively simple arrangement of many serially post-maxillary appendages (trunk limbs), this taxon also shows an often unappreciated large variation in appendage morphology. Diplostracan branchiopods exhibit generally a division of labor into locomotory antennae and feeding/filtratory post-maxillary appendages (trunk limbs). We here study the functionality and morphology of the swimming antennae and feeding appendages in clam shrimps and cladocerans and analyze the findings in an evolutionary context (e.g., possible progenetic origin of Cladocera). We focus on Cyclestheria hislopi (Cyclestherida), sister species to Cladocera and exhibiting many "large" branchiopod characters (e.g., many serially similar appendages), and Sida crystallina (Cladocera, Ctenopoda), which likely exhibits plesiomorphic cladoceran traits (e.g., six pairs of serially similar appendages). We combine (semi-)high-speed recordings of behavior with confocal laser scanning microscopy analyses of musculature to infer functionality and homologies of locomotory and filtratory appendages in the two groups. Our morphological study shows that the musculature in all trunk limbs (irrespective of limb size) of both C. hislopi and S. crystallina comprises overall similar muscle groups in largely corresponding arrangements. Some differences between C. hislopi and S. crystallina, such as fewer trunk limbs and antennal segments in the latter, may reflect a progenetic origin of Cladocera. Other differences seem related to the appearance of a specialized type of swimming and feeding in Cladocera, where the anterior locomotory system (antennae) and the posterior feeding system (trunk limbs) have become fully separated functionally from each other. This separation is likely one explanation for the omnipresence of cladocerans, which have conquered both freshwater and marine free water masses and a number of other habitats.

Fine-scale appendage structure of the Cambrian trilobitomorph Naraoia spinosa and its ontogenetic and ecological implications.

Trilobitomorphs are a species-rich Palaeozoic arthropod assemblage that unites trilobites with several other lineages that share similar appendage structure. Post-embryonic development of the exoskeleton is well documented for some trilobitomorphs, especially trilobites, but little is known of the ontogeny of their soft parts, limiting understanding of their autecology. Here, we document appendage structure of the Cambrian naraoiid trilobitomorph Naraoia spinosa by computed microtomography, resulting in three-dimensional reconstructions of appendages at both juvenile and adult stages. The adult has dense, strong spines on the protopods of post-antennal appendages, implying a predatory/scavenging behaviour. The absence of such gnathobasic structures, but instead tiny protopodal bristles and a number of endopodal setae, suggests a detritus-feeding strategy for the juvenile. Our data add strong morphological evidence for ecological niche shifting by Cambrian arthropods during their life cycles. A conserved number of appendages across the sampled developmental stages demonstrates that Naraoia ceased budding off new appendages by the mid-juvenile stage.

New Antimycobacterial Leads from Multicomponent Hydrazino-Ugi Reaction.

Previously, modification of isoniazide- and pyrazinamide-derived pharmacophores via the Ugi multicomponent reaction proved to be an effective strategy to obtain efficacious and non-cytotoxic antimycobacterial leads. To apply the hydrazino-Ugi reaction developed in our group toward modifying these pharmacophores with similar appendages as reported previously; to create hydrolytically more stable compounds which are based on acyl hydrazine, rather than diamide backbone. Six hydrazino-Ugi products were synthesized and modified at the reactive nitrogen atom via reductive alkylation. Additionally, by conducting the hydrazino-Ugi reaction in methanol, three methyl ester by-products were obtained and tested alongside the main library. Compounds were screened against M. tuberculosis H37Rv strain and checked for cytotoxicity vs. HEK293 cells. Hydrolytic stability of a model Ugi and one of the newly synthesized hydrazino-Ugi products was compared in rat plasma stability experiments. 6 out of 20 compounds prepared and tested, displayed potent inhibition of M. tuberculosis growth and virtually no cytotoxicity in the testing concentration range. The stability of a sample hydrazino-Ugi product in rat plasma was over 3 times higher compared to that of one of the Ugi products reported earlier. Hydrazino-Ugi reaction represents an effective way to modify classical antitubercular chemotypes and generate compounds endowed with specific antimycobacterial activity. These are new, hydrolytically stable leads for the future antitubercular therapy development.

The Role of Nerve Signaling in Limb Genesis and Agenesis During Axolotl Limb Regeneration

Vertebrate appendages such as limbs and fins share evolutionarily conserved mechanisms for development and regeneration, implying that they evolved from an appendage that arose on a common ancestor1. This conservation of developmental mechanisms is one of the fundamental discoveries of molecular genetics and is the basis for our emerging understanding of the evolution of animal genomes. The molecules involved in the signaling pathways that regulate limb development are not only conserved at the level of nucleotides and/or amino acids but also at the functional level, so that experimentally substituting homologous genes between species as divergent as humans and Drosophila can rescue the function of a mutant gene2. The fact that this remarkable degree of conservation has been maintained over the course of evolution implies that the mechanisms for appendage development have evolved once. Similarly, the mechanisms regulating limb regeneration are largely the same as those regulating limb development3,4, and thus evolution appears to have selected for a conserved set of signaling pathways that regulate both vertebrate limb development and regeneration. There are three important conclusions that can be drawn on the basis of the conservation of developmental and regenerative mechanisms among tetrapods (the group of vertebrates with four feet or legs or similar appendages, including amphibians, reptiles, birds, and mammals). The first is that, since development and regeneration to a large degree utilize the same mechanisms3,4, it follows that humans therefore possess the genetic pathways (genes) that will be required for regenerating a limb because these are the same genes that were used when human adults were embryos5. After a blastema has formed (Fig. 1), it appears to be equivalent to a developing limb bud in the embryo, both at the molecular and functional levels. In …

Eocladoxylon (Protopteridium) minutum (Halle) Koidzumi from the Middle Devonian of Yunnan, China: An Early Rhacophyton‐Like Plant?

New specimens of Eocladoxylon (Protopteridium) minutum (Halle) Koidzumi collected from the Middle Devonian Xichong Formation, Yunnan province, China, demonstrate three orders of branching. Sterile branching systems have a pinnate two‐dimensional branching pattern with alternate insertion of lower orders. Up to several times deeply dissected, overall wedge‐shaped, flattened appendages are inserted alternately on the third order of branching. Second and third orders of branching have an opposite pair of similar appendages inserted at the base, perpendicular to the plane of the remaining branching system. Fertile appendages, consisting of a dichotomous axial system and terminal pairs of sporangia attached closely in groups of eight, replace the sterile appendages in fertile branches. Anatomy of a probable second‐order axis demonstrates a bipolar clepsydroid vascular system. The sterile branching system and anatomy bear some similarity to the Late Devonian fernlike plant Rhacophyton. Eocladoxylon is neither a cladoxylopsid nor a progymnosperm, as was previously believed. The potential for an ancestor/descendant relationship between Iridopteridales and Rhacophyton via Eocladoxylon is briefly discussed in the context of the geographical isolation of the Middle Devonian flora of South China.

A new polymorphic species of Laboulbenia parasitic on a South American fly

Morphologically different thalli of Laboulbenia richardiana sp. nov. (Laboulbeniales, Ascomycota) were found on various parts of the body of the South American fly Richardia teevani. These thalli lack a separate cell IV and have similar appendages and perithecial apices. They are interpreted here as 'growth forms' of a single biological species. Spore characteristics and insect behavior support this view, rather than the hypothesis of several different species displaying position specificity.

Appendages of Unknown Function in Male Pupae of some Ant species (Hymenoptera: Formicidae)

Male pupae of Tetraponera attenuata Smith 1877 (Pseudomyrmecinae) have a pair of conspicuous bladder-like appendages originating at the posterior-interior bases of the hind leg femora, and rising upwards between the femora and the epinotum. A second, smaller pair of similar appendages is found on top of the wing articulations. In gyne and worker pupae of T attenuata such appendages are lacking. In male pupae of other species of the genus, T nitida (Smith 1860), 7' binghami (Forel 1902), and T pilosa (Smith 1858), occurring in the same area in Malaysia, no such appendages were found. The structures are similar to the appendages described from male pupae of Leptothorax (Macromischa) subditivus (Wheeler 1903) and L cf tenuisculptus Baroni Urbani 1978 (Myrmicinae). Apparently they are mere projections of the pupal cuticula, filled with exuvial fluid. As yet, no function can be assigned to any of these appendages, nor is anything known on their distribution among the Formicidae.

Electron Microscopic Observations of Flavobacterium aquatile NCIB 8694 (= ATCC 11947) and Flavobacterium meningosepticum NCTC 10016 (= ATCC 13253)

Electron microscopic observations of Flavobacterium aquatile NCIB 8694 (type strain) revealed the presence of nonflagellar appendages. Similar appendages were not found on Flavobacterium meningosepticum NCTC 10016 (type strain).

A horned beetle which fights

HORNS, and other often elaborate forms of prothoracic and cephalic armature, are a well known feature of male and occasionally female beetles in the family Scarabaeidae (Coleoptera)1. Many of these, including rhinoceros beetles (Dynastinae) and dung beetles (Scarabaeinae, Geotrupinae), have been studied in detail, but the function of the horns is still the subject of dispute2. The idea that in certain circumstances it would be an advantage for male insects to fight for the possession of a female or a breeding site, and that horns and similar appendages have evolved as weapons, has recently been put forward by Hamilton3. The male of the geotrupine Typhoeus typhoeus (L.) is well armed in this way (Fig. 1), and the observations that I report here show for the first time in a burrowing beetle, not only that the horns are used for fighting between males, but that they are specifically designed for the purpose.

ELECTRON MICROSCOPY OF FLAGELLATION OF VIBRIO PARAHAEMOLYTICUS.

The structure of the bacterial flagellum of which diameter lies far below the resolving power of the light microscope came to be observed by the electron microscope. Recently the flagellar structure consisting of the flagellum (central filament or core) and the surrounding sheath has been demonstrated in some bacteria (De Robertis and Franchi. 1951; van Iterson, 1953; Labow, and Mosley. 1955; Braun, 1956; Gordon, and Follett, 1962; Glauert, Kerridge, and Horne, 1963 ). Vibrio comma and El Tor vibrio which cultured on the brain heart infusion agar or on the cooked meat media were found to have an appendage, undulating membrane, which was fairly observed by the negative staining method using the phosphotungstenic acid ~ Ogasawara, and Kuno, 1963 ). This paper reports on the existence of a similar appendage of Vibrio parahaemolyticus which could be observed by the negative staining method (Brenner and Horne, 1959).

II. On the structure and functions of the hairs of the crus­tacea

The object of this communication is to determine, by the observa­tion of their anatomical relations, the uses of the hairs and similar appendages to the shell of the Crustacea. The author mentions the observations of those who have of late specially investigated this sub­ject. M. Lavalle noticed the connexion at times of the canals of the hairs with canals penetrating the whole thickness of the shell, and the occasional continuity of the matter which filled the hairs with that which exists in the corresponding canal of the shell. M. Hollard says that the canals of the shell which correspond to the hairs, are occupied by membranous investments, which embrace the base of the hairs, and seem to receive an extension of the nutrient system. He suggests that amongst other functions, the hairs may possibly be con­nected with that of general sensibility. Dr. Hackel in a recent pub­lication has shown that the canals of the shell and hair are lined by a continuation of the outer layer of the soft internal integument, which he calls the chitinogenous layer. He describes minutely the structure of the inner integument, and his account on the whole agrees with that given by Milne-Edwards; but he does not recognize the presence in the canals, of any of the elements of the inner integument except the external cuticular or chitinogenous layer; nor the connexion of these canals with the corium which lies beneath it, and which receives abundantly nerves and vessels.

XXIII. Observations on Episcopal Chairs and Stone Seats; as also on Piscinas and other appendages to Altars still remaining in Chancels; with a Description of Chalk Church, in the Diocese of Rochester. In a Letter from Mr. Charles Clarke, to the Rev. Samuel Denne, F.A.S.

Among the ecclesiastical remains of this country the seats fixed on the South side the chancels of parochial and other churches, having but very lately been honoured with a share in the labours of your pen, I judged you might receive some trifling gratification in being made acquainted that a religious edifice, at a small distance from this place, was decorated with a specimen of these reliques, nearly unique. This information you were not only pleased kindly to accept, but also to favour me, by signifying your desire that I should give an explanation of this and similar appendages. Stimulated by your wishes, and happy in the proposed opportunity of collecting together my scattered notions on these and one or two relative subjects, I am now about to offer to your consideration the best account I have been enabled to obtain, of the uses for which they were designed by our ancestors; and permit me to observe, on the part of my endeavour, that littie or nothing has been hazarded to conjecture, that what ever favoured of mystery, or was any way phantastical, has been as much as possible avoided; and that, as far as they could be had, vouchers of the most genuine worth in such affairs have been consulted and produced: “Authoribus quidem ad istam sententiam, quam vis obtineri, uti optimis possumus: quod in omnibus causis et debet et solet valere plurimum: et primum quidem omni antiquitate; quæ quo propius aberat ab ortu et divina progenie, hoc melius ea fortasse, quæ erant vera, cernebat.”